document_title: Drinking water supply and sanitation in the United States

question_text: where do most cities get their water supply

question_tokens: where do most cities get their water supply

root

text: Drinking water supply and sanitation in the United States

text: History[edit]

text: In the 19th century numerous American cities were afflicted with major outbreaks of disease, including cholera in 1832, 1849 and 1866 and typhoid in 1848.[17] The fast-growing cities did not have sewers and relied on contaminated wells within the city confines for drinking water supply. In the mid-19th century many cities built centralized water supply systems. However, initially these systems provided raw river water without any treatment. Only after John Snow established the link between contaminated water and disease in 1854 and after authorities became gradually convinced of that link, water treatment plants were added and public health improved. Sewers were built since the 1850s, initially based on the erroneous belief that bad air (miasma theory) caused cholera and typhoid. It took until the 1890s for the now universally accepted germ theory of disease to prevail.

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text: However, most wastewater was still discharged without any treatment, because wastewater was not believed to be harmful to receiving waters due to the natural dilution and self-purifying capacity of rivers, lakes and the sea. Wastewater treatment only became widespread after the introduction of federal funding in 1948 and especially after an increase in environmental consciousness and the upscaling of financing in the 1970s. For decades federal funding for water supply and sanitation was provided through grants to local governments. After 1987 the system was changed to loans through revolving funds.

text: Piped water supply until 1948[edit]

text: In the 1840s and 1850s the largest cities in the U.S. built pipelines to supply drinking water from rivers or lakes. However, the drinking water was initially not treated, since the link between waterborne pathogens and diseases was not yet well known. In 1842 New York City was one of the first cities in the U.S. to tap water resources outside the city limits. It dammed the Croton River in Westchester County, New York, and built an aqueduct from the reservoir to the city.[18] Also in 1842, construction was completed on Chicago's first water works, with water mains made of cedar and a water intake located about 150 feet (46 m) into Lake Michigan.[19] In 1848, Boston began construction of a water transmission system. A tributary of the Sudbury River was impounded creating Lake Cochituate, from where the Cochituate Aqueduct transported water to the Brookline Reservoir that fed the city's distribution system.[20] In 1853 Washington, D.C. followed suit by beginning the construction of the Washington Aqueduct to provide water from the Great Falls on the Potomac River.[21]

text: In 1854, the British physician John Snow found that cholera was spread through contaminated water. As a result of his findings, several cities began to treat all water with sand filters and chlorine before distributing it to the public. Cities also began to construct sewers.[22] As a result of water treatment and sanitation, the incidence of cholera and typhoid rapidly decreased. Slow sand filtration was initially the technology of choice for water treatment, later being gradually displaced by rapid sand filtration.

text: In the arid American Southwest, the water demand of rapidly growing cities such as Los Angeles exceeded local water availability, requiring the construction of large pipelines to bring in water from far-away sources. The most spectacular example is the first Los Angeles Aqueduct built between 1905 and 1913 to supply water from the Owens Valley over a distance of 375 km.

text: Sanitation until 1948[edit]

text: Most of the first sewer systems in the United States were built as combined sewers (carrying both storm water and sewerage). They discharged into rivers, lakes and the sea without any treatment. The main reason for choosing combined sewers over separate systems (separating sanitary sewers from storm water drains) was a belief that combined sewer systems were cheaper to build than separate systems. Also, there was no European precedent for successful separate sewer systems at the time.[17] The first large-scale sewer systems in the United States were constructed in Chicago and Brooklyn in the late 1850s, followed by other major U.S. cities.[17]

text: Few sewage treatment facilities were constructed in the late 19th century to treat combined wastewater because of the associated difficulties. There were only 27 U.S. cities with wastewater treatment works by 1892, most of them "treating" wastewater through land application. Of these 27 cities, 26 had separate sanitary and storm water sewer systems, thus facilitating wastewater treatment, because there was no need for large capacitites to accommodate wet weather flows. Furthermore, there was a belief that the diluted combined wastewater was not harmful to receiving waters, due to the natural dilution and self-purifying capacity of rivers, lakes and the sea.[17] In the early 20th century a debate evolved between those who thought it was in the best interest of public health to construct wastewater treatment facilities and those who believed building them was unnecessary. Nevertheless, many cities began to opt for separate sewer systems, creating favorable conditions for adding wastewater treatment plants in the future.[17]

text: Where wastewater was being treated it was typically discharged into rivers or lakes. However, in 1932, the first reclaimed water facility in the U.S. was built in Golden Gate Park, San Francisco, for the reuse of treated wastewater in landscape irrigation.

text: Sanitary sewers were not the only sanitation solution applied. They were particularly useful in high-density urban areas. However, in some newly built lower-density areas, decentralized septic systems were built. They were attractive because they reduced capital expenditures and had fewer operation and maintenance costs compared to wastewater treatment plants.[17]

text: After 1948: Enter the federal government[edit]

text: In the first half of the 20th century water supply and sanitation were a local government responsibility with regulation at the state level; the federal government played almost no role in the sector at that time. This changed with the enactment of the Federal Water Pollution Control Act of 1948, which provided for comprehensive planning, technical services, research, and financial assistance by the federal government to state and local governments for sanitary infrastructure. The Act was amended in 1965, establishing a uniform set of water quality standards and creating a Federal Water Pollution Control Administration authorized to set standards where states failed to do so.[17] Comprehensive federal regulations for water supply and sanitation were introduced in the 1970s, in reaction to an increase in environmental concerns. In 1970 EPA was created by the Richard Nixon administration, and authority for managing various environmental programs was transferred to the new agency.[23] In 1972, Congress passed the Clean Water Act, requiring industrial plants and municipal sewage plants to proactively improve their waste treatment practices in order to limit the effect of contaminants on freshwater sources.[24] In 1974, the Safe Drinking Water Act was adopted for the regulation of public water systems. This law specified a number of contaminants that must be closely monitored and reported to residents should they exceed the maximum contaminant levels allowed. From then on, drinking water systems were closely monitored by federal, state, and municipal governments for safety and compliance with existing regulations.[22] The Clean Water Act set the unprecedented goal of eliminating all water pollution by 1985 and authorized massive expenditures of $24.6 billion in research and construction grants for municipal sewage treatment. The funds initially provided an incentive to build centralized wastewater collection and treatment infrastructure for municipalities, instead of decentralized systems.[17] However, the 1977 amendments to the Clean Water Act required communities to consider alternatives to the conventional centralized sewer systems, and financial assistance was made available for such alternatives.[17] In the mid-1990s decentralized systems served approximately 25 percent of the U.S. population, and approximately 37 percent of new housing developments.[25]

text: There were disagreements between the federal government and local government about the appropriate level of wastewater treatment, with the former arguing for more stringent standards. For example, in the late 1980s, the city of San Diego and EPA were involved in a legal dispute over the requirement to treat sewage at the Point Loma Wastewater Treatment Plant to secondary treatment standards. The city prevailed, saying that it saved ratepayers an estimated $3 billion and that process had proved successful in maintaining a healthy ocean environment. The Point Loma plant uses an advanced primary process.[26] The requirement to perform secondary treatment on wastewater before ocean discharge was waived by the EPA in 1995, "taking into account the city's unique circumstances".[27]

text: In 1987 Congress passed the Water Quality Act, which replaced the construction grant program with a system of subsidized loans using the Clean Water State Revolving Fund (CWSRF).[28] The intention at the time was to completely phase out federal funding after a few years. Funding peaked in 1991 and continued at high levels thereafter, despite the original intentions. New challenges arose, such as the need to address combined sewer overflows for which EPA issued a policy in 1994.[29] In 1996 Congress established the Drinking Water State Revolving Fund, building on the success of the CWSRF, in order to finance investments to improve compliance with more stringent drinking water quality standards.[30]

text: Technical and environmental overview[edit]

text: This section provides a brief overview of the water supply and sanitation infrastructure in the U.S., water sources of some of the main cities, and the main types of residential water use.

text: Infrastructure[edit]

text: The centralized drinking water supply infrastructure in the United States consists of dams and reservoirs, well fields, pumping stations, aqueducts for the transport of large quantities of water over long distances, water treatment plants, reservoirs in the distribution system (including water towers), and 1.8 million miles of distribution lines.[5]:14 Depending on the location and quality of the water source, all or some of these elements may be present in a particular water supply system. In addition to this infrastructure for centralized network distribution, 14.5% of Americans rely on their own water sources, usually wells.[11][12]

text: The centralized sanitation infrastructure in the U.S. consists of 1.2 million miles of sewers—including both sanitary sewers and combined sewers, sewage pumping stations and 16,024 publicly owned wastewater treatment plants.[31] In addition, at least 17% of Americans are served by on-site sanitation systems such as septic tanks.[32]

text: Publicly owned wastewater treatment plants serve 189.7 million people and treat 32.1 billion gallons per day.[31] 9,388 facilities provide secondary treatment, 4,428 facilities provide advanced treatment, and 2,032 facilities do not discharge.[31] There are 176 facilities that provide a treatment level that is less than secondary. These include facilities with ocean discharge waivers, and treatment facilities discharging to other facilities meeting secondary treatment or better. 880 facilities receive flows from combined sewer systems.[31] About 772 communities in the U.S. have combined sewer systems, serving about 40 million people.[33]

text: Water sources[edit]

text: About 90% of public water systems in the U.S. obtain their water from groundwater. However, since systems served by groundwater tend to be much smaller than systems served by surface water, only 34% of Americans (101 million) are supplied with treated groundwater, while 66% (195 million) are supplied with surface water.[10]

text: For a surface water system to operate without filtration it has to fulfill certain criteria set by the EPA under its Surface Water Treatment Rule, including the implementation of a watershed control program. The water system of New York City has repeatedly fulfilled these criteria.[34]

text: Cities supplied primarily by surface water without water treatment[edit]

text: Boston, New York City, San Francisco, Denver, and Portland, Oregon are among the large cities in the U.S. that do not need to treat their surface water sources beyond disinfection, because their water sources are located in the upper reaches of protected watersheds and thus are naturally very pure.[35] Boston receives most of its water from the Quabbin and Wachusett Reservoirs and the Ware River in central and western Massachusetts. New York City's water supply is fed by a 2,000-square-mile (5,200 km2) watershed in the Catskill Mountains. The watershed is in one of the largest protected wilderness areas in the United States.[36] San Francisco obtains 85% of its drinking water from high Sierra snowmelt through the Hetch Hetchy Reservoir in Yosemite National Park.[37] However, to supplement the imported water supply, and to help maintain delivery of drinking water in the event of a major earthquake, drought or decline in the snowpack, San Francisco considers the use of alternative locally produced, sustainable water sources such as reclaimed water for irrigation, local groundwater and desalination during drought periods, all as part of its Water Supply Diversification Program.[38] The largest source of water supply for Portland, Oregon, is the Bull Run Watershed.[39] Denver receives its water almost entirely from mountain snowmelt in a number of highly protected watersheds in more than 9 counties. Its water is stored in 14 reservoirs, the largest of which is the Dillon Reservoir on the Blue River in the Colorado River. Water is diverted from there through the Harold D. Roberts Tunnel under the Continental Divide into the South Platte River Basin.[40]

text: Cities supplied primarily by surface water with water treatment[edit]

text: Cities that rely on more or less polluted surface water from the lower reaches of rivers have to rely on extensive and costly water purification plants. The Las Vegas Valley obtains 90% of its water from Lake Mead on the Colorado River, which has been affected by drought.[41] To supply a portion of the future water supply, Las Vegas plans to buy water rights in the Snake Valley in White Pine County, 250 mi (400 km) north of the city straddling the Utah border and other areas, pumping it to Las Vegas through a US$2 billion pipeline.[42] Phoenix draws about half of its drinking water from the Salt River–Verde River watershed, and about 40% from the Colorado River further downstream at Lake Havasu through the Central Arizona Project. Los Angeles obtains about half of its drinking water from the Owens River and Mono Lake through the Los Angeles Aqueduct,[43] with additional supplies from Lake Havasu through the Colorado River Aqueduct.[44] San Diego imports nearly 90 percent of its water from other areas, specifically northern California and the Colorado River.[45]

text: The cities on the Mississippi River are supplied by water from that river except for Memphis. The metropolitan area of Atlanta receives 70% of its water from the Chattahoochee River and another 28% from the Etowah, Flint, Ocmulgee and Oconee rivers.[46] Chicago is supplied by water from Lake Michigan and Detroit receives its water from the Detroit River.[47] Philadelphia receives 60% of its water from the Delaware River and 40% from the Schuylkill River.[48] Washington, D.C. receives its water from the Potomac River through the Washington Aqueduct.[49]

text: Cities supplied primarily by groundwater[edit]

text: Miami and its metropolitan area obtain drinking water primarily from the Biscayne Aquifer. Given increasing water demand, Miami-Dade County is considering the use of reclaimed water to help preserve the Biscayne Aquifer.[50] Memphis receives its water from artesian aquifers.[51] San Antonio draws the bulk of its water from the Edwards Aquifer;[52][53] it did not use any surface water until 2006.[54]

text: Cities supplied by a mix of groundwater and surface water[edit]

text: Seventy-one percent of Houston's supply flows from the Trinity River into Lake Livingston, and from the San Jacinto River into Lake Conroe and Lake Houston. Deep underground wells drilled into the Evangeline and Chicot aquifers provide the other 29 percent of the city's water supply.[55]

text: Water use[edit]

text: Domestic water use (also called home or residential water use) in the United States was estimated by the United States Geological Survey at 29.4 billion US gallons (111,000,000 m3) per day in 2005,[56] and 27.4 billion US gallons (104,000,000 m3) per day in 2010 (7 percent lower).[1] The bulk of domestic water is provided through public networks. 13% or 3.6 billion US gallons (14,000,000 m3) of water is self-supplied.[1] The average domestic water use per person in the U.S. was 98-US-gallon (370 L) per day in 2005,[56] and 88-US-gallon (330 L) per day in 2010.[1] This is about 2.2 times as high as in England (150 Liter)[57] and 2.6 times as high as in Germany (126 Liter).[58][59]

text: One of the reasons for the high domestic water use in the U.S. is the high share of outdoor water use. For example, the arid West has some of the highest per capita domestic water use, largely because of landscape irrigation. Per capita domestic water use varied from 51-US-gallon (190 L) per day in Maine to 148-US-gallon (560 L) per day in Arizona and 167-US-gallon (630 L) per day in Utah.[1] According to a 1999 study, on average all over the U.S. 58% of domestic water use is outdoors for gardening, swimming pools etc. and 42% is used indoors.[60] A 2016 update of the 1999 study measured the average quantities and percent shares of seven indoor end uses of water:[61]

text:
24% Toilets
3% Baths
20% Showers
17% Clothes Washers
1% Dishwashers
19% Faucets
4% Other Domestic Uses[61]

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text: Only a very small share of public water supply is used for drinking. According to one 2002 survey of 1,000 households, an estimated 56% of Americans drank water straight from the tap and an additional 37% drank tap water after filtering it.[62] 74% of Americans said they bought bottled water.[62] According to a non-representative survey conducted among 216 parents (173 Latinos and 43 non-Latinos), 63 (29%) never drank tap water. The share is much higher among Latinos (34%) than among non-Latinos (12%). The study concluded that many Latino families avoid drinking tap water because they fear it causes illness, resulting in greater cost for the purchase of bottled and filtered water.[63] This notion is also repeated among Asians.[63]

text: Institutional overview[edit]

text: Service providers[edit]

text: EPA defines a public water system (PWS) as one that provides water for human consumption through pipes or other constructed conveyances to at least 15 service connections or serves an average of at least 25 people for at least 60 days a year. The agency has defined three types of PWS:

text:
Community Water System (CWS). A PWS that supplies water to the same population year-round.
Non-Transient Non-Community Water System (NTNCWS). A PWS that regularly supplies water to at least 25 of the same people at least six months per year, but not year-round. Some examples are schools, factories, office buildings, and hospitals which have their own water systems.
Transient Non-Community Water System (TNCWS). A PWS that provides water in a place such as a gas station or campground where people do not remain for long periods of time.[64]

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text: In 2007 there were about 155,000 PWSs in the United States, of which 52,000 CWSs. PWSs are either publicly owned, cooperatives or privately owned,[6] serving a total of about 242 million people in 2000. EPA estimates the number of beneficiaries of community water systems at 288 million in 2007[6] The United States Geological Survey estimates that "About 242 million people depended on water from public suppliers" in 2000.[65] Four thousand systems provide water in localities with more than 10,000 inhabitants, and the remaining 50,000 systems provide water in localities with less than 10,000 inhabitants.[6] In 2000 15% of Americans (43.5 million people) relied on their own water source, usually a well, for drinking water.[56][66]

text: Utilities in charge of public water supply and sanitation systems can be owned, financed, operated and maintained by a public entity, a private company or both can share responsibilities through a public-private partnership. Utilities can either be in charge of only water supply and/or sanitation, or they can also be in charge of providing other services, in particular electricity and gas. In the latter case they are called multi-utilities. Bulk water suppliers are entities that manage large aqueducts and sell either treated or untreated water to various users, including utilities.

text: Public service providers. Eighty-nine percent of Americans served by a public water system are served by a public or cooperative entity.[67][68] Usually public systems are managed by utilities that are owned by a city or county, but have a separate legal personality, management and finances. Examples are the District of Columbia Water and Sewer Authority, the Los Angeles Department of Water and Power and Denver Water. In some cases public utilities span several jurisdictions. An example is the Washington Suburban Sanitary Commission that spans two counties in Maryland. Utility cooperatives are a major provider of water services, especially in small towns and rural areas[69][70]

text: Private utilities. About half of American drinking water utilities, or about 26,700, are privately owned, providing water to 11% of Americans served by public water systems.[67] Most of the private utilities are small, but a few are large and are traded on the stock exchange. The largest private water company in the U.S. is American Water, which serves 15 million customers in 1,600 communities in the U.S. and Canada.[71] It is followed by United Water, which serves 7 million customers and is owned by the French firm Suez Environnement.[72] Overall, about 33.5 million Americans (11% of the population) get water from a privately owned drinking water utility.[67] In addition, 20% of all wastewater utilities in the U.S. are privately owned, many of them relatively small. About 3% of Americans get wastewater service from private wastewater utilities. In addition, more than 1,300 government entities (typically municipalities) contract with private companies to provide water and/or wastewater services.[67]

text: Multi-utilities. Some utilities in the U.S. provide only water and/or sewer services, while others are multi-utilities that also provide power and gas services. Examples of utilities that provide only water and sewer services are the Boston Water and Sewer Commission, Dallas Water Utilities, the New York City Department of Environmental Protection, Seattle Public Utilities and the Washington Suburban Sanitary Commission. Other utilities, such as the San Francisco Public Utilities Commission, provide power in addition to water and sewer services. Other multi-utilities provide power and water services, but no sewer services, such as the Los Angeles Department of Water and Power and the Orlando Utilities Commission. There are also some utilities that provide only sewer services, such as the Metropolitan Water Reclamation District of Greater Chicago or the sewer utility in the city of Santa Clara.[73]

text: Bulk water suppliers. There are also a few large bulk water suppliers in the arid Southwest of the United States, which sell water to utilities. The Metropolitan Water District of Southern California (MWD) sells treated water from the Colorado River and Northern California to its member utilities in Southern California through the California Aqueduct. Twenty-six cities and water districts serving 18 million people are members of MWD.[74] The Central Arizona Water Conservation district supplies water from the Colorado River to 80 municipal, industrial, agricultural and Indian customers in Central and Southern Arizona through the Central Arizona Project Aqueduct (CAP).[75]

text: Regulators[edit]

text: The economic regulation of water and sanitation service providers in the U.S. (in particular in relation to the setting of user water rates) is usually the responsibility of regulators such as Public Utility Commissions at the state level, which are organized in the National Association of Regulatory Utility Commissioners.[76] (see economic regulator). However, while all investor-owned utilities are subject to tariff regulation, only few public utilities are subjected to the same regulation. In fact, only 12 states have laws restricting pricing practices by public water and sanitation utilities.[77]

text: The environmental and drinking water quality regulation is the responsibility of state departments of health or environment and the EPA.[78]

text: Other stakeholders[edit]

text: There are a number of Professional associations, trade associations and other non-governmental organizations (NGOs) that are actively engaged in water supply and sanitation.

text: Professional associations include the American Water Works Association (AWWA) oriented mainly towards drinking water professionals and the Water Environment Federation (WEF) geared mainly at wastewater professionals. The geographical scope of both is greater than the U.S.: AWWA has members in 100 countries,[79] with a focus on the U.S. and Canada, and WEF has member associations in 30 countries.[80]

text: There are a number of trade associations in the sector, including:

text:
The National Association of Water Companies (NAWC), founded in 1895, which represents the interests of small and large private water and wastewater utilities;[81]
The National Association of Clean Water Agencies (NACWA), founded in 1970, which represents the interests of wastewater utilities;[82]
The National Rural Water Association (NRWA), founded in 1976, which represents small water and wastewater utilities;[69]
The Association of Metropolitan Water Agencies (AMWA), founded in 1981, which represents the interests of large publicly owned drinking water utilities.[83]
The Water Reuse Association, founded in 2000, which promotes water reclamation, recycling, reuse and desalination.[84]
The Water Quality Association represents manufacturers and dealers of equipment for water treatment.[85]

text: In addition to lobbying, some of these trade associations also provide public education, as well as training and technical assistance to their members.[86][87]

text: An example of an NGO active in water supply and sanitation is Food & Water Watch, a consumer rights group created in 2005 which focuses on corporate and government accountability relating to food, water, and fishing. Another example is the Alliance for Water Efficiency (AWE), which was created in 2007 with seed funding from the EPA to "advocate for water efficiency research, evaluation, and education" at the national level. Its Board members "represent water utilities, environmental organizations, plumbing and appliance associations, irrigation manufacturers, the academic community, government, and others."[88]

text: Issues[edit]

text: Among the main issues facing water users and the water industry in the U.S. in 2009 are water scarcity and adaptation to climate change; concerns about combined sewer overflows and drinking water quality; as well as concerns about a gap between investment needs and actual investments. Other issues are concerns about a swiftly retiring workforce, the affordability of water bills for the poor during a recession, and water fluoridation, which is opposed by some mainly on ethical and safety grounds.

text: Water scarcity and climate change[edit]

text: With water use in the United States increasing every year, many regions are starting to feel the pressure. At least 36 states are anticipating local, regional, or statewide water shortages by 2013, even under non-drought conditions.[89]

text: According to the National Academies, climate change affects water supply in the U.S. in the following ways:

text:
Rising water demands. Hotter summers mean thirstier people and plants. In addition, more evaporation from reservoirs and irrigated farmland will lead to faster depletion of water supplies.
Increased drought. Scientific evidence suggests that rising temperatures in the southwestern United States will reduce river flows and contribute to an increased severity, frequency, and duration of droughts.
Seasonal supply reductions. Many utilities depend on winter snowpack to store water and then gradually release it through snowmelt during spring and summer. Warmer temperatures will accelerate snowmelt, causing the bulk of the runoff to occur earlier and potentially increasing water storage needs in these areas.[9]

text: Pollution[edit]

text: An important turning point in managing drinking water pollution in the United States occurred after passage of the Safe Drinking Water Act of 1974, which required the National Academy of Sciences (NAS) to conduct a study of the issue. The NAS found that there really was not a lot of information available on drinking water quality. Perhaps the most important part of the study, according to senior EPA officials responsible for implementing the 1974 law, was that it described some methodologies for doing risk assessments for chemicals that were suspected carcinogens.[90]

text: Sewer overflows. Combined sewer overflows (CSO) and sanitary sewer overflows affect the quality of water resources in many parts of the U.S. About 772 communities have combined sewer systems, serving about 40 million people, mostly in the Northeast, the Great Lakes Region and the Pacific Northwest.[33] CSO discharges during heavy storms can cause serious water pollution. A 2004 EPA report to Congress estimated that there are 9,348 CSO outflows in the U.S., discharging about 850 billion US gallons (3.2×109 m3) of untreated wastewater and storm water to the environment.[91] EPA estimates that between 23,000 and 75,000 sanitary sewer overflows occur each year, resulting in releases of between 3 and 10 billion US gallons (38,000,000 m3) of untreated wastewater.[91]

text: The increased frequency and intensity of rainfall as a result of climate change[8][92] will result in additional water pollution from wastewater treatment, storage, and conveyance systems."[92] For the most part, wastewater treatment plants and combined sewer overflow control programs have been designed on the basis of the historic hydrologic record, taking no account of prospective changes in flow conditions due to climate change.[92]

text: Drinking water quality. There are several aspects of drinking water quality that are of some concern in the United States, including Cryptosporidium,[93] disinfection by-products, lead, perchlorates and pharmaceutical substances. However, in almost all cases drinking water quality is in conformity with the norms of the Safe Drinking Water Act, which sets Maximum Contaminant Levels for pollutants. In addition, the EPA's Consumer Confidence Rule of 1998 requires most public water suppliers to provide consumer confidence reports, also known as annual water quality reports, to their customers.[94] According to the EPA, each year by July 1 anyone connected to a public water system should receive in the mail an annual water quality report that tells where water in a specific locality comes from and what's in it. Consumers can find out about these local reports on a map provided by EPA.[95] 29% of Americans are reading their water quality reports. Customers are generally satisfied with the information they are receiving from their water companies and their local or state environmental offices.[62]

text: Investment gap[edit]

text: In its Infrastructure Report Card the American Society of Civil Engineers gave both the U.S. drinking water and wastewater infrastructure a grade of D- in 2005, down from D in 2001. According to the report, "the nation's drinking water system faces a staggering public investment need to replace aging facilities, comply with safe drinking water regulations and meet future needs."[96] Investment needs are about $19 billion/year for sanitation and $14 billion/year for drinking water, totaling $33 billion/year.[97] State and local governments invested $35.1 billion in water supply and sanitation in 2008, including 16.3 billion for drinking water supply and 18.8 billion for sanitation.[98]

text: As of 2013, the American Society of Civil Engineers report card remains a "D", and a recent paper from Stanford University's Center for Reinventing the Nation's Urban Water Infrastructure (ReNUWIt) describes why "water infrastructure is systemically resistant to innovation":

text: Despite a growing sense that water will be as important a global issue as energy in the coming century, capital deployed for water resources "pales in comparison to that for renewable energy." ... Only 5 percent of the $4.3 billion in VC money invested in the clean tech industry goes to water technologies.

text: Federal support is also on the decline. The membranes that today enable desalinization and water reuse, for example, were the fruits of R&D undertaken during the Kennedy administration. We now spend ten times less on that research.[99]

text: The paper notes that innovations occur when utilities see opportunities for "short-term benefits and immediate savings," when there are water shortages, and in quality of life situations, like Philadelphia's "green infrastructure initiative designed to reduce combined sewer overflow."[99]

text: Concerning drinking water supply the EPA estimated in 2003 that $276.8 billion would have to be invested between 2003 and 2023.[100][101] Concerning sanitation, the EPA estimated in 2007 that investment of $202.5 billion is needed over the next 20 years to control wastewater pollution. This includes $134 billion for wastewater treatment and collection, $54.8 billion for resolving unsatisfactory combined sewer overflows and $9 billion for stormwater management.[102] The EPA needs surveys do not capture all investment needs, in particular concerning capital replacement.[97]

text: Access[edit]

text: In the U.S, in 2015, about 2.7 million people still lacked access to "improved" water. Regarding sanitation, in 2015, only around 36000 people did not have access to "improved" sanitation.[103][104]

text: More than 99% of the U.S. population has access to "complete plumbing facilities", defined as the following services within the housing unit:

text:
hot and cold piped water,
bathtub or shower, and
flush toilet.

text: However, more than 1.6 million people in the United States, in 630,000 households, still lack basic plumbing facilities.[105] More than a third of them have household incomes below the federal poverty level. They are spread across all racial and ethnic categories, but they are more prominent in the minority groups. Most of the people who lacked plumbing services were elderly, poor, and living in rural areas. Alaska has the highest percentage of households without plumbing – 6.32 percent of all its households.[106]

text: Pricing and affordability[edit]

text: The median household in the U.S. spent about 1.1% of its income on water and sewerage in 2002. However, poor households face a different situation: In 1997 18% of U.S. households, many of them poor, paid more than 4% of their income on their water and sewer bill.[107]

text: The mean U.S. water tariff – excluding sewer tariffs – was $2.72 per 1,000 gallons ($0.72 per cubic meter) in 2000,[108]:29 with significant variations between localities. Average residential water tariffs for a monthly consumption of 15 cubic meters varied between $0.35 per cubic meter in Chicago and $3.01 in Atlanta in 2007. The combined water and sewer tariff was $0.64 in Chicago and $3.01 in Atlanta, with Atlanta not charging separately for sewer services.[109] Annual combined water and sewer bills vary between $228 in Chicago and $1,476 in Atlanta in 2008.[110] For purposes of comparison, the average water and sewer bill in England and Wales in 2008 was equivalent to $466.[111]

text: The average annual increase in typical residential water bills was approximately 5.3 percent from 2001 through 2009, while the increase in typical residential sewer bills was approximately 5.5 percent according to data from the 50 Largest Cities Water and Wastewater Rate Survey by Black & Veatch.[112]

text: Retiring workforce[edit]

text: The water community in the US is faced with a swiftly retiring workforce and a tightening market place for new workers. In 2008, approximately one third of executives and managers were expected to retire in the following five years.[113] Water and sanitation utilities in the United States had 41,922 employees in 2002.[114]

text: Fluoridation[edit]

text: Water fluoridation, the controlled addition of moderate concentrations of fluoride to a public water supply to reduce tooth decay, is used for about two-thirds of the U.S. population on public water systems.[115] Almost all major public health and dental organizations support water fluoridation, or consider it safe.[116] Nevertheless, it is contentious for ethical, safety, and efficacy reasons.[117]

text: Responses to address issues[edit]

text: Supply-side management[edit]

text: Historically the predominant response to increasing water demand in the U.S. has been to tap into ever more distant sources of conventional water supply, in particular rivers. Because of environmental concerns and limitations in the availability of water resources, including droughts that may be due to climate change, this approach now is in many cases not feasible any more. Still, supply-side management is often being pursued tapping into non-conventional water resources, in particular seawater desalination in coastal areas with high population growth. California alone had plans to build 21 desalination plants in 2006 with a total capacity of 450 million US gallons (1,700,000 m3) per day, which would represent a massive 70-fold increase over current seawater desalination capacity in the state.[118] In 2007 the largest desalination plant in the United States is the one at Tampa Bay, Florida, which began desalinating 25 million US gallons (95,000 m3) of water per day in December 2007.[119]

text: In 2005 over 2,000 desalination plants with a capacity of more than 100m3/day had been installed or contracted in every state in the U.S. with a total capacity of more than 6 million m3/day. Only 7% of that capacity was for seawater desalination, while 51% used brackish water and 26% used river water as water source.[120] The contracted capacity corresponds to 2.4% of total municipal and industrial water use in the country in 2000.[121] The actual share of desalinated water is lower, because some of the contracted capacity was never built or never operated, was closed down or is not operated at full capacity.[120]

text: Demand-side management[edit]

text: Demand-side management, including the reduction of leakage in the distribution network and water conservation, are other options that are being considered and, in some cases, also applied to address water scarcity. For example, Seattle has reduced per capita water use from 152 US gallons (580 L) per day in 1990 to 97 US gallons (370 L) per day in 2007 through a comprehensive water conservation program including pricing policies, education, regulations and rebates for water-saving appliances. Other cities such as Atlanta and Las Vegas have also launched water conservation programs that are somewhat less comprehensive than the one in Seattle concerning indoor water use. However, Las Vegas has intentionally focused on curbing outdoor water demand, which accounts for 70% of residential water use in the city, through reductions in turf area and incentives for the use of rains sensors, irrigation controllers and pool covers.[122] At the federal level, the Energy Policy Act of 1992 set standards for water-efficient appliances, replacing the 3.5 US gallons (13 L) per flush (gpf) toilet with a new 1.6 gpf/6 litres per flush maximum standard for all new toilets. By 1994, federal law mandated that showerheads and faucets sold in the U.S. release no more than 2.5 and 2.2 US gallons (8.3 L) of water per minute respectively.[123] Also in 1994 the AWWA established a clearinghouse for water conservation, efficiency, and demand management, called WaterWiser, to assist water conservation professionals and the general public in using water more efficiently.[124] In 2006 the EPA launched its WaterSense program to encourage water efficiency beyond the standards set by the Energy Policy Act through the use of a special label on consumer products.[125][126]

text: Distributional losses in the U.S. are typically 10–15% of total withdrawals, although they can exceed 25% of total water use in older systems.[122] According to another source unaccounted-for water (UFW) – which includes system losses, water used for firefighting and water used in the treatment process – was estimated to be only 8% in systems with more than 500,000 connections in 2000.[127]:17 In comparison, the level of water losses is 7% in Germany, 19% in England and Wales, and 26% in France. Together with Germany water losses in the U.S. are thus among the lowest in 16 industrial countries.[128]

text: Low water tariffs and inappropriate tariff structures do not encourage water conservation. For example, decreasing-block rates, under which the unit rate decreases with consumption, offer hardly any incentive for water conservation. In 2000 about 51% of water tariffs in the U.S.were uniform (i.e. the unit tariff is independent of the level of consumption), 12% were increasing-block tariffs (the unit rate increases with consumption) and 19% were decreasing-block tariffs.[108] The use of decreasing-block tariffs declined sharply from 45% of all tariff structures in 1992.[77] Sewer rates are often flat rates that are not linked to consumption, thus offering no incentive to conserve water.[122]

text: Water reuse[edit]

text: Reuse of reclaimed water is an increasingly common response to water scarcity in many parts of the United States. Reclaimed water is being reused directly for various non-potable uses in the United States, including urban landscape irrigation of parks, school yards, highway medians and golf courses; fire protection; commercial uses such as vehicle washing; industrial reuse such as cooling water, boiler water and process water; environmental and recreational uses such as the creation or restoration of wetlands; as well as agricultural irrigation.[129] In some cases, such as in Irvine Ranch Water District in Orange County it is also used for flushing toilets.[130]

text: It was estimated that in 2002 a total of 1.7 billion US gallons (6,400,000 m3) per day, or almost 3% of public water supply, were being directly reused. California reused 0.6 and Florida 0.5 billion US gallons (1,900,000 m3) per day respectively. Twenty-five states had regulations regarding the use of reclaimed water in 2002.[129] Planned direct reuse of reclaimed water was initiated in 1932 with the construction of a reclaimed water facility at San Francisco's Golden Gate Park. Reclaimed water is typically distributed with a color-coded dual piping network that keeps reclaimed water pipes completely separate from potable water pipes.[131]

text: The leaders in use of reclaimed water in the U.S. are Florida and California,[132] with Irvine Ranch Water District as one of the leading developers. They were the first district to approve the use of reclaimed water for in-building piping and use in flushing toilets.

text: In places like Florida, where it is necessary to avoid nutrient overload of sensitive receiving water, reuse of treated or reclaimed water can be more economically feasible than meeting the higher standards for surface water disposal mandated by the Clean Water Act[133]

text: In a January 2012 U.S. National Research Council report,[134] a committee of independent experts found that expanding the reuse of municipal wastewater for irrigation, industrial uses, and drinking water augmentation could significantly increase the United States’ total available water resources.[135] The committee noted that a portfolio of treatment options is available to mitigate water quality issues in reclaimed water. The report also includes a risk analysis that suggests the risk of exposure to certain microbial and chemical contaminants from drinking reclaimed water is not any higher than the risk from drinking water from current water treatment systems—and in some cases, may be orders of magnitude lower. The report concludes that adjustments to the federal regulatory framework could enhance public health protection and increase public confidence in water reuse.

text: There are examples of communities that have safely used recycled water for many years. Los Angeles County's sanitation districts have provided treated wastewater for landscape irrigation in parks and golf courses since 1929. The first reclaimed water facility in California was built at San Francisco's Golden Gate Park in 1932. The Water Replenishment District of Southern California was the first groundwater agency to obtain permitted use of recycled water for groundwater recharge in 1962.

text: The Irvine Ranch Water District (IRWD) was the first water district in California to receive an unrestricted use permit from the state for its recycled water; such a permit means that water can be used for any purpose except drinking. IRWD maintains one of the largest recycled water systems in the nation with more than 400 miles serving more than 4,500 metered connections. The Irvine Ranch Water District and Orange County Water District in Southern California are established leaders in recycled water. Further, the Orange County Water District, located in Orange County, water is given more advanced treatments and is used indirectly for drinking.[136]

text: The Trinity River in Texas is a representative example of an effluent-dominated surface water system where de facto potable water reuse occurs. The section of the river south of Dallas/Fort Worth consists almost entirely of wastewater effluent under base flow conditions. In response to concerns about nutrients, the wastewater treatment plants in Dallas/Fort Worth that collectively discharge about 2 million m3 per day of effluent employ nutrient removal processes. Little dilution of the effluent-dominated waters occurs as the water travels from Dallas/Fort Worth to Lake Livingston, which is one of the main drinking water reservoirs for Houston. Once the water reaches Lake Livingston, it is subjected to conventional drinking water treatment prior to delivery to consumers in Houston.[137]

text: Non-potable reuse (NPR)[edit]

text:
Austin, Texas[138]
Clark County, Nevada[139]
Clearwater, Florida[140]
Contra Costa County, California[141]
San Antonio[142] operates the largest recycled water system in the United States.
Tucson, Arizona[143]
San Diego, California (San Diego County)[144]
St. Petersburg, Florida[145]

text: Indirect potable reuse (IPR)[edit]

text: Orange County is located in Southern California, USA, and houses a classic example in IPR.[146] A large-scale artificial groundwater recharge scheme exists in the area, providing a much-needed freshwater barrier to intruding seawater.[147] Part of the injected water consists of recycled water, starting as of 1976 with Water Factory 21, which used RO and high lime to clean the water (production capacity of 19,000 m3 per day).[148][149] This plant was de-commissioned in 2004 and has since made place for a new project with a higher capacity (265,000 m3 per day with an ultimate capacity of 492,000 m3 per day), under the name of Groundwater Replenishment System.[149][150] This newer scheme uses the newer technological combination of RO, MF, and ultraviolet light with hydrogen peroxide.[149][151] Plans are also underway to further increase the capacity of the system,[150] which already provides up to 20% of the water used by the country.[152]

text: In the USA, San Diego, California is the leading state implementing IPR. MF, RO and UV/H2O2 are employed prior to groundwater replenishment with the treated effluents (CDPH, 2013). In San Diego, the effort to increase the share of recycled water was rekindled with an extensive study in 2006.[149] MF provides substantial removal of the dissolved effluent organic matter (dEfOM), while dEfOM reduction down to 0.5 mg/L (in terms of TOC) is achieved through RO application. The chemical oxidation treatment (UV/H2O2) following the membrane steps, results in the mitigation of N-nitrosodimethylamine (NDMA), as well as in the improvement of the effluent quality with respect to its organic content.[153]

text: The City of El Paso’s (Texas, USA) water sources include groundwater aquifers and surface water from the Rio Grande. In order to increase groundwater levels, the El Paso Water Utilities injects advanced treated reclaimed water into the aquifer. The advanced treatment facilities use two-stage powdered activated carbon (PAC), addition of lime, two-stage recarbonation, sand filtration, ozonation, granular activated carbon (GAC), and chlorination for purifying the water.[154] The Hueco Bolson Recharge Project, which initially began in 1985, currently recharges 1,700 acre-feet per year of reclaimed water at 10 injection wells and 800 acre-feet per year at an infiltration basin for groundwater recharge.[155]

text: In Colorado, USA, the Colorado River Municipal Water District implemented a project to capture treated municipal effluent from the City of Big Spring, and provide additional advanced treatment prior to blending into their raw surface water delivery system (2012). Advanced treatment of the municipal effluent consisted of MF, RO, and ultraviolet oxidation, producing very high quality water, which is blended with surface water from Lake E.V. Spence for distribution to their member and customer cities (production of 6,700 m3 per day).[155]

text: Further examples:

text:
Big Spring, Texas indirect potable reuse program[156]
Orange County, California[157][158]
Pasadena, California[159]
Singapore[160] (where it is branded as NEWater)
Payson, Arizona[161]
The Torreele project in the Veurne coastal region of Belgium, which began operating in 2002"[162]
Virginia Occoquan Reservoir - The Upper Occoquan Sewage Authority plant discharges its highly treated output to supply roughly 20% of the inflow into the Occoquan Reservoir, which provides drinking water used by the Fairfax County Water Authority - one of the three major water providers in the Washington, D.C. metropolitan area.
Windhoek, Namibia[163][160]
Wichita Falls, Texas (toilet-to-tap reuse as a temporary measure during drought conditions, 2014-2015;[156] Indirect potable use 2015)[164]

text: Direct Potable Reuse (DPR)[edit]

text: In July 2014, the city of Wichita Falls, Texas (USA), became one of the first in the United States to use treated wastewater directly in its drinking water supply (production of 45,000-60,000 m3 per day). Treated wastewater is disinfected and pumped to the Cypress Water Treatment Plant where it goes through clarification, microfiltration (MF), reverse osmosis (RO), and ultraviolet light disinfection before being released into a holding lagoon where it is blended with lake water (50:50). The blended water goes through a seven-step conventional surface water treatment.[165]

text: Proposed projects:

text:
Los Angeles, California - By 2019, the Los Angeles Department of Water and Power will build a plant to replenish their groundwater aquifer with purified water[166] in order to deal with the shortage of rain and snow fall, restricted water imports and local groundwater contamination.[167]
San Diego, California (San Diego County)[160]

text: Pollution control[edit]

text: Numerous efforts have been undertaken in the United States to control the pollution of water resources and to make drinking water safe. The most comprehensive federal regulations and standards for the water treatment industry were implemented in the 1970s, in reaction to a huge increase in environmental concerns in the country. In 1972, Congress passed the Clean Water Act (CWA), with the unprecedented goal of eliminating all water pollution by 1985 and authorized expenditures of $24.6 billion in research and construction grants.[168] In 1974, Congress passed the Safe Drinking Water Act, specifying a number of contaminants that had to be closely monitored and reported to residents should they exceed the maximum contaminant levels.[169] The CWA included substantial federal grant funding to improve sewage treatment infrastructure in the form of construction grants to local governments.

text: The 1987 Water Quality Act amended the CWA, replacing the sewage treatment construction grant program with a system of subsidized loans, using the Clean Water State Revolving Fund (CWSRF). The loans use a combination of 80% federal funds and 20% matching funds from states.[170] The intention at the time was to completely phase out federal funding after a few years. Funding for the CWSRF peaked in 1991 and continued at high levels thereafter, despite the original intentions.[171] New challenges arose, such as the need to address combined sewer overflows for which EPA issued a policy in 1994, and which was codifed into law by Congress in 2000.[172] In 1996 Congress established the Drinking Water State Revolving Fund, in order to finance investments to improve compliance with more stringent drinking water quality standards.[30]

text: Today cities make significant investments in the control of combined sewer overflows, including through the construction of storage facilities in the sewerage system in order to allow for the subsequent controlled release of sewage into treatment plants.

text: Federal assistance[edit]

text: One way to address the funding needs of utilities to respond to the various challenges they face without increasing the burden of water bills on users is federal financial assistance.

text: Centralized water and sanitation infrastructure is typically financed through utilities' own revenue or debt. Debt can be in the form of soft loans from State Revolving Funds (SRF), credits from commercial Banks or – in the case of large utilities – from bonds issued directly in the capital market. In the case of water supply (i.e. excluding sanitation), 42% of investments were financed by private sector borrowing, 39% by current revenues, 13% by government loans including the Drinking Water SRF, 5% by government grants and 1% from other sources.[5] Although federal funding for the main of the two SRFs has declined in real terms by 70% between its peak in 1991 and 2006, SRFs play an important role in financing water and sanitation investments.[171][173][174] There are two SRFs: The larger Clean Water State Revolving Fund, created in 1987,[175][176][177] and the smaller Drinking Water State Revolving Fund, created in 1997.[31] They receive federal and state contributions and issue bonds. In turn, they provide soft loans to utilities in their respective states, with average interest rates at 2% for up to 20 years in the case of the Clean Water State Revolving Fund. In addition to the SRFs, the United States Department of Agriculture provides grants, loans and loan guarantees for water supply and sanitation in small communities (those with less than 10,000 inhabitants), together with technical assistance and training.[178]

text: The American Recovery and Reinvestment Act of February 17, 2009, provides $4 billion for the Clean Water SRF, $2 billion for the Drinking Water SRF and, among others, $126 million for water recycling projects through the United States Bureau of Reclamation.[179]

text: This exceeds previous levels of financing, since Congress approved only US$1.5 billion of federal funding for State Revolving Funds in 2008. This was much below the historical average of US$3 billion/year for the Clean Water State Revolving Fund (1987–2006)[176][180] and US$1.2 billion/year for the Drinking Water State Revolving Fund (1997–2005).[31] The share of federal funding for sanitation has declined from almost 50% in the early 1980s to about 20% in the early 1990s.[181] A May 2016 article asserted that there has been "a huge federal retreat from helping cities fund water projects," stating that overall federal spending on water utilities "has dropped 75 percent since 1977," and that experts expect more situations like the Flint water crisis to emerge.[182]

text: Congress passed the Water Infrastructure Finance and Innovation Act of 2014 (WIFIA) to provide an expanded credit program for water and wastewater infrastructure projects, with broader eligibility criteria than the previously-authorized revolving funds.[183] Pursuant to the act, EPA established its Water Infrastructure and Resiliency Finance Center in 2015 to help local governments and municipal utilities design innovative financing mechanisms, including public-private partnerships. It is part of the federal government's Build American Investment Initiative.[184] Congress amended the WIFIA program in 2015 and 2016.[185] One of the envisaged instruments to boost financing in water infrastructure are Qualified Public Infrastructure Bonds (QPIBs), tax-exempt municipal bonds that can be used by private companies.[186]


document_title: Prenatal memory

question_text: when does the fetus begin to develop memory

text: Prenatal memory

text: Background Information and Functions[edit]

text: There is some evidence that fetal memory may begin within the second trimester after conception. Substantial evidence for fetal memories has been found at around 30 weeks after conception.[1] Fetal memory is important for parental recognition, and facilitates the bond between child and parents. One of the most important types of memory is that which stores information contributing to the maternal bond between infant and mother. This form of memory is important for a type of development known as attachment.[2] Fetal memory is thus critical to the survival of the fetus both prenatally (in the womb) and after birth as an infant.

text: Development[edit]

text: The Central Nervous System (CNS) and memory in the fetus develop from the ectoderm following fertilization via a process called neurulation. The ectoderm is the outermost layer of the embryo. This happens towards the end of the third week of gestation (time period when the embryo is carried in the women's uterus) and ends with the start of the development of the neural tube, an important structure crucial to development of the central nervous system. Some evidence suggests memory is actually responsible for carrying out the development of the CNS during neurulation. However, much more research needs to be done on this. Fetal memory and brain development can be impaired by a number of maternal implications. Rubella, intrauterine hypoxia and hypothyroidism are some of the more researched examples. Alcohol and other substances such as hard drugs can affect this process as well.[citation needed]

text: Functions[edit]

text: Once neurulation is complete and has given rise to the nervous system, fetal memory becomes responsible for a variety of tasks. One of its main functions at this point is to control breathing in the fetus. Also noted, was its ability to control eye movement and coordination during all nine months of development. There is evidence that these are practiced in the womb and carried out similarly after birth. Learning language as an infant also requires fetal memory. It is now known that the mother's voice is clearly heard from inside the womb and that the fetus can differentiate speech sounds, particularly the phonemes (a single segment of sound) in speech. This is evident in the baby when born, showing many signs of early language comprehension. It has also been shown that infants prefer their mother’s native language after being exposed to it in the womb. Evidence also exists that the infant, when born, prefers its mother's smell from having memorized her scent as a fetus. Memory is critical for the recognition process that takes place between the mother and infant through breastfeeding. Breast milk contains contents recognizable by the infant that they were exposed to through amniotic fluid (fluid that encompasses the fetus and is responsible for its nutrition in the womb) in the fetal stage. Since the baby is so dependent upon the mother, maternal nutrition also plays a large role in the infant developing healthy brain functioning; including memory function, which the infant cannot live without. Thus, fetal memory is critical to the survival and healthy development of the infant before and after birth. Many of these functions are measured through methods such as classical conditioning, habituation and exposure learning, being the most popular.[2]

text: Measurement techniques[edit]

text: There are considered to be three paradigms used to investigate fetal learning and memory. They are: classical conditioning, habituation and exposure learning.[3]

text: Classical Conditioning[edit]

text: Classical conditioning is described as the pairing of a conditioned stimulus (CS) (such as a vibration) with an unconditioned stimulus (US) (such as a loud noise) to evoke a conditioned response (CR) (agitation). In this pairing, the vibration will be presented immediately followed by a loud noise. Initially, the presentation of the loud noise (US) would cause the unconditioned response (UR) (natural agitation) without prior classical conditioning. However, the continuous pairing of the loud noise (US) with the vibration (CS) converts the unconditioned response (UR) into a (CR) as the fetus learns that the presentation of a vibration will be followed by a loud noise. Eventually, the fetus will respond to the vibration (CS) without being exposed to the loud noise (US); this is when conditioning has occurred. Conditioning has been demonstrated in as few as 12-15 pairings of the vibration (CS) with the loud noise (US) in fetuses as early as 32 weeks of gestation.[3] Another study replicated these findings.[2]

text: Fetuses between 32 and 39 weeks gestation were presented a pure tone (CS), which was paired with a vibroacoustic stimulus (US). A vibroacoustic stimulus is a low bass sound frequency that is felt by the fetus as a mechanical vibration.[4] After 10-20 pairings, approximately 50% of the fetuses showed successful conditioning, unrelated to age or sex of the fetus. It is suggested that poorly prepared experimental set up, inaccurate or inappropriate response measures and unsuitable stimuli could all contribute to failed conditioning, as opposed to lack of fetal memory.[2] Reasons for some fetuses demonstrating conditioning, while others do not, remains undetermined.

text: Habituation[edit]

text: The second paradigm, habituation, is one of the most successful ways of investigating fetal memory. Habituation has been demonstrated in fetuses as early as 22 weeks and corresponds to the onset of fetal auditory abilities.[5][6][7][8] Both auditory and vibroacoustic stimulation have been used in habituation. Vibroacoustic stimulation is a technique involving the repetitive stimulation of the fetus, by applying a vibroacoustic stimulus (in predetermined intervals) to the abdomen of the mother. The movement and reaction of the fetus, in response to the stimulus, is recorded using ultrasound technology. This process is repeated until habituation, defined as a lack of response to the stimulus by the fetus, is reached. Stimulation trials continue into the neonatal period (first 28 days after birth) by presenting the same auditory stimulus, to test whether or not the fetus has memory of the stimulation events. A scientific control group of babies in the neonatal period, having not been exposed to the stimulus as a fetus, are used in neonatal trials to serve as a comparison.

text: Results from another recent study suggest that fetuses were able to form both short and long term memories.[9] This conclusion was drawn from the fact that habituation rates (number of stimuli needed to habituate) were higher in babies in the neonatal stage that had not previously undergone fetal stimulations when compared to those who had: therefore demonstrating the memory of the stimulus in its fetal stage being carried into the neonatal stage.

text: Exposure Learning[edit]

text: The final experimental technique used to investigate fetal learning and memory is exposure learning. This technique allows the experimenter a lot of control over the presentation of the stimulus and following testing.[2] Exposure learning is the act of presenting the fetus with a stimulus, such as a television theme tune, repeatedly while in the womb and then testing recognition (learning) of that tune after birth. One experiment was conducted where fetuses were exposed to the television theme tune from the show "Neighbours" while in the womb.[10] In the first condition of the experiment, newborns age 2–4 days that were exposed to the tune while in the womb were presented with the tune after birth. Upon hearing the tune, these newborns showed physiological changes, such as a decrease in heart rate. This observed change did not happen with unfamiliar tunes, or to newborns that were not exposed to the tune in the womb; so the tune had to be learned in the womb. Recognition of the tune was strong 2–4 days after birth, however, diminished after the age of 21 days without repeated exposure.[10]

text: A second exposure learning experiment, using the television theme tune, was conducted to determine when learning and memory could first take place in utero. It was determined that by 30–37 weeks of gestation, fetuses previously exposed to the theme tune were more active when presented with the tune than those who had no previous experience with the tune. This demonstrates that stimulus recognition begins no earlier than 30 weeks of gestation.[11]

text: Implications[edit]

text: Overall, studies indicate that there is an ability for fetal learning and memory, and through classical conditioning, habituation and exposure learning that memory can be measured. It is important to note that certain periods in fetal development allow for different learning and memory abilities, which should be taken into consideration when determining if fetal memory exists. Auditory stimuli presented in the womb can be retained and recognized (learned) into the days following birth and that learning is specific to familiar auditory stimuli.[12][13] Measuring learning and memory in the fetus has only been discussed in terms of healthy pregnancies; however, many factors such as disease affect these delicate processes.

text: Diseases and conditions affecting fetal memory[edit]

text: Much research and literature has shown that endocrine, neurological and most other diseases a mother or father carries can have adverse effects on a fetus's development.[14] The majority of the research done regarding fetal brain development, and consequently its memory after birth, has focused on one condition or state and two main diseases: intrauterine hypoxia, hypothyroidism and rubella.

text: Intrauterine hypoxia[edit]

text: Intrauterine hypoxia is a condition or state caused by insufficient oxygen levels reaching a fetus during gestation, having detrimental effects on the development of its central nervous system (CNS).[15] In many cases, intrauterine hypoxia results in the death of the fetus. Commonly known, the CNS is vital to the communication and response transmissions between the brain and all of the body parts within an organism. Due to dysfunction in this system such things as cognitive functioning and attention capacity are impeded, resulting in a poor ability to decode or encode information and form memories.[16] It has also been discovered that lower levels of oxygen reaching the developing fetus may, in fact, decrease the amount of grey matter produced within its brain[17] and increase the amount of sulcal (referring to a sulcus: a fissure within the surface of the brain) cerebrospinal fluid (CSF); importantly in the frontal lobe and temporal lobe, which are critical memory centers.[18] The later point regarding sulcal CSF has been linked to schizophrenia (a mental disorder affecting thought processes). Grey matter is a large component of the CNS and is related to: muscle control, sensory perceptions, memory, emotions and speech; please follow this link for more information regarding the different brain structures and their effects on human function.[19]

text: Hypothyroidism[edit]

text: Hypothyroidism is a disease that may have severe, adverse effects on the brain development in a fetus. These problems are often caused by a "passing-down" from the mother or from an external neurotoxin causing impaired cognitive ability and, in extreme cases, mental retardation.[20]

text: Hypothyroidism is usually caused by an iodine deficiency that results in the under production of thyroid hormones or an underdeveloped thyroid gland with similar effects.[15] Thyroid hormone release is regulated by a stimulating hormone called thyrotropin (TSH) in a normal functioning person. In abnormal cases when there are lowered levels of thyroid hormone, TSH levels increase to compensate, thus doctors and medical researchers can measure TSH levels to predict hypothyroidism.[21] If interested, a good explanation of this process and the consequences of abnormal levels of TSH can be found under this link.[22] Reduced levels of thyroid hormones have many physical and cognitive implications for a fetus once fully developed. Because of ethical reasons, most research has been carried out on rats and other mammals. However, in the hypothyroid rat brain, numerous malformations were found: reduced myelin of neurons in the CNS, deficiency of neurons in the cerebral cortex, the visual cortex and auditory cortex, hippocampus and cerebellum, which relate to general learning and motor skill acquisition.[23]

text: Rubella[edit]

text: Rubella, synonymous with German measles, is a disease caused by a virus with the same name and is highly contagious. It is often combated using preventative measures, typically through vaccination. For children and adults it can be overcome quite easily once vaccinated, however, if the fetus is exposed to the virus, especially during the first trimester (the first three months of pregnancy), major implications can occur.[24] Rubella, in a pregnant woman, can lead to autism or autistic-like symptoms and congenital rubella syndrome for her offspring after birth. It is essential to keep in mind that this is not conclusive and still remains a theory. Congenital rubella syndrome has many adverse effects such as: mental retardation, meningitis and encephalitis. The latter two ailments also affect cognition and learning capacities.

text: Implications and future possibilities[edit]

text: As a result of ethical consideration, most research into diseases and conditions affecting fetal development has been restricted to the use of other animals aside from human beings. Most accounts on the implications caused by diseases or conditions like rubella, hypothyroidism and intrauterine hypoxia involving humans have come from studies done on patients later in life, or more appropriately, after birth. Although there is much evidence that points towards these prenatal diseases or conditions being precursors for improper brain development, and thus potential consequences for memory, it is hard to assume that these alone are the only cause. If one could test for, and track the onset of the disease during gestation while screening potential extraneous variables, one may be able to better understand this topic. It is important to remember[according to whom?] that this is a newer, less explored, aspect of memory research. If anything can be taken from this, it should be that most of these diseases or conditions resulting in poor fetal brain development can be prevented or mitigated if one exercises healthy living behaviour. A large part of this involves proper nutrition and dieting.[citation needed]

text: Fetal Nutrition and Memory[edit]

text: Fetal nutrition has implications for both the short term and long term development of the brain. Due to ethical reasons, studies, which may result in diminished physical functioning or short/long-term damage, are generally done on animals before being deemed safe for human trials.

text: There are two points in rodent brain development during which treatment with choline, a neurotransmitter, produces lifelong enhancement of spatial memory.

text: The first point is at 12–17 days into embryo development, and the second is between 16–30 days after the rat has been born. Baby rats, from mothers fed a diet lacking in choline during these two periods of pregnancy, have poorer memory function than baby rats from mothers who received choline. Choline, when given during these critical periods, causes a major improvement in memory performance when rats are being trained in a maze. Even in older rats, these memory changes persist and can be used to easily identify which rats came from mothers that received enough choline. Supplementation with choline appears to reduce the speed at which memory declines with age. Choline before pregnancy is also related to changes in the birth, death, and migration of cells in the hippocampus during the development of the baby rats in the womb. Choline is also associated with the different location and shape of neurons involved in memory storage within the brain.[25]

text: In another study using rats, it was found that the size of the hippocampus (the central region in memory functioning) was affected by protein malnutrition. More specifically, only the CA1 region of the hippocampus seemed to demonstrate a significant reduction in size. The CA1 subsection of the hippocampus was 20% smaller in offspring from mothers who were fed a protein deficient diet while pregnant. Because the region of the hippocampus affected by protein malnutrition is so specific, global hippocampal function is not impaired, but rather just the function that would appear to be associated with the CA1. Rats with the CA1 volume deficit were found to perform poorly in a tasks requiring behavioural inhibition and accurate response timing.[26]

text: As both of these studies have only been done on rats, it is still unknown for certain whether the same effects of choline would be seen in humans. Further research in this area is needed.[citation needed]

text: Longitudinal Memory Effects of Prenatal Drug Exposure[edit]

text: Similarly to nutritional intake, drugs consumed by the mother during pregnancy can affect the brain development of her fetus. There has been a great deal of research concerned with the damaging effects of prenatal drug use, and how exactly this use impairs future memory functioning of the child. Research has focused on a variety of recreational drugs, primarily alcohol, cocaine, heroin, and methamphetamine.

text: Pregnancy Category[edit]

text: Most drugs are rated by the Food and Drug Administration to a pregnancy category, which is a government assessment of the risks to the fetus that drug use by the mother incurs. The pregnancy category levels (from least to most dangerous) are A, B, C, D and X and are described as follows:[27]

text:
Category A: "Adequate and well-controlled studies have failed to demonstrate a risk to the fetus in the first trimester of pregnancy (and there is no evidence of risk in later trimesters)"
Category B: "Animal reproduction studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women"
Category C: "Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks"
Category D: "There is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience or studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks"
Category X: "Studies in animals or humans have demonstrated fetal abnormalities and/or there is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience, and the risks involved in use of the drug in pregnant women clearly outweigh potential benefits"

text: Alcohol[edit]

text: Alcohol is the most widely used of these drugs, and for that reason, the majority research on prenatal drug use has been focused on it. Research shows that prenatal exposure to alcohol can have many negative consequences, and is significantly associated with memory problems, attention problems and decreased cognitive functioning (mental processes involved in memory, perception, thinking etc.) for the offspring later in life. Also, it can lead to the development of alcohol-related problems in later years, such as alcohol dependence.

text: One study compared data about maternal drinking during pregnancy (alcohol consumption by the pregnant mother), to observations gathered about the offspring many years after birth.[28] The mother’s alcoholic drinking levels during mid pregnancy were measured via self-report measures (a questionnaire). In this longitudinal study (a study which measures participant changes over time through repeated measures), the offspring also reported their drinking habits at 21 years of age, and completed the Alcohol Dependence Scale (a self-report questionnaire).[29] The results suggested that there is a significant correlation between prenatal alcohol exposure and the presence of dangerous alcohol problems at age 21. Episodic drinking (multiple drinks during drinking occasions) by the mother significantly increased subsequent Alcohol Dependence scores for their children.

text: One of the items on the Alcohol Dependence scale most positively related to their prenatal alcohol exposure includes "blacking out". Blackouts are alcohol-related amnesia, occurring when long term memory creation is impaired during a drinking episode, resulting in an inability to remember. The frequency of blackouts in young adults while drinking is strongly related to prenatal alcohol exposure; those exposed to alcohol as a fetus are more vulnerable to experiencing blackouts as an adult.Prenatal alcohol exposure can also lead to decreased problem solving skills and/or attention deficits. Attention deficits result in an inability to maintain focus on one task for a length of time, and being prone to distraction.[28]

text: Another study examined the relationship between prenatal alcohol exposure and executive functioning performance through a number of tests.[30] Executive functions are a group of processes that serve to regulate more basic brain functions such as memory, motor skills and attention. Patients who had been exposed prenatally to alcohol show decreased ability to hold and manipulate information in working memory, (the memory system that is used to keep things in mind during complex tasks). Those with Fetal Alcohol Syndrome (FAS) and Fetal Alcohol Effects (FAE), (defects caused by a mother's alcohol consumption during pregnancy), have poor problem solving skills compared to control participants (participants that do not have either FAS or FAE). The memory tests used to assess the participants in this study included the following:

text:
Consonant Trigrams Test (CTT) – a measure of working memory. The participant attempts to remember three consonants, while having to count backwards by three through various delays.
Digit Span – another measure of working memory. The participant is given a set of numbers and is asked to recount as many as possibly afterwards.
California Verbal Learning Test (CVLT) – tests for lists which are learned over repeated trials.

text: Prenatal alcohol exposure directly affects the ability to switch tasks, maintain attention as well as keep and manipulate information in working memory despite distraction. Therefore, in almost all cases in this study, the patients with FAS or FAE had inferior performance on the tests when compared to the control group. Patterns show that longitudinal memory effects of prenatal alcohol exposure manifest themselves both directly and also indirectly through lower IQ.

text: Cocaine[edit]

text: Cocaine is an addictive stimulant, and although there is not a comparable academic research base to alcohol, there are a fair number of studies which show adverse effects to memory performance after prenatal exposure. The pregnancy category level of cocaine is C, as described above.

text: Prenatal exposure to cocaine has also been linked to decreased cognitive functioning in school aged children, including lower scores in short-term memory assessments. Short-term memory is the memory system responsible for holding information in an easily accessible state for a short period of time. One particular study examined the effects of prenatal cocaine exposure, among other factors, on cognitive ability in children.[31] In this specific assessment, the Stanford-Binet IV Test, an IQ test, was given to children who were exposed to cocaine in utero (before birth) as well as a control group of children (not exposed to cocaine in utero). Overall, those children who were exposed to cocaine during pregnancy had lower scores on the Short Term Memory scale than unexposed children at all age levels, especially boys. Cocaine exposure also predicted lower IQ scores in general. Exposing prenatal offspring to cocaine can cause irreversible damage and increase developmental risks, especially for boys.[citation needed]

text: A review of 42 follow up studies of prenatal drug exposed children suggests that cocaine affects the areas concerned with behavior problems, attention, language and cognition for children tested between 4 and 13 years of age. Specifically, short-term memory, visual spatial short-term memory (short-term memory for visual information specifically) and working memory were negatively affected in a number of studies.[32]

text: Heroin[edit]

text: Prenatal exposure research is less abundant for opiates, such as heroin. Despite this, heroin is given a pregnancy risk level of X, the highest rating. One study suggested that children exposed to prenatal heroin performed worse in memory subscales of the McCarthy Scales. In other words, youth who had been prenatally exposed to heroin performed worse on general cognitive tasks, including those associated with memory.[32]

text: Methamphetamine[edit]

text: Methamphetamine, commonly known as meth, is another stimulant that has been demonstrated to have negative effects on the offspring of a pregnant woman, and is considered a level C pregnancy category drug. One study attempted to determine the neurotoxic effects (harm to nerve cells) of prenatal methamphetamine exposure on brain development, as well as on cognitive functioning. Children exposed to meth in utero scored lower on key measures of memory performance, including attention, verbal memory and long term spatial memory.[citation needed]

text: The reduced size of brain structures associated with memory and attention was also noted through magnetic resonance imaging (MRI), a process used to produce images of the brain for observation. For example, those with prenantal meth exposure had, on average, a smaller hippocampus (a brain structure involved in many things, including memory) than control participants. This reduction in size was correlated with poorer sustained attention (decreased ability to focus on a single task for a period of time) and delayed verbal memory (memory of words read or heard). The conclusion from this study is that prenatal meth exposure can be neurotoxic to the developing fetus brain.[33]