Water Availability--The Connection Between Water Use and Quality

Water availability has become a high priority in the United States, in large part because competition for water is becom ing more intense across the Nation. Population growth in many areas competes with demands for water to support irrigation and power production. Cities, farms, and power plants compete for water needed by aquatic ecosystems to support their minimum flow requirements. At the same time, naturally occurring and human-related contaminants from chemical use, land use, and wastewater and industrial discharge are introduced into our waters and diminish its quality.

The fact that degraded quality limits the availability and suitability of water for critical uses is a well-known reality in many communities. What may be less understood, but equally true, is that our everyday use of water can significantly affect water quality, and thus its availability. Landscape features (such as geology, soils, and vegetation) along with water-use prac tices (such as ground-water withdrawals and irrigation) govern water availability because, together, they affect the movement of chemical compounds over the land and in the subsurface. Understanding the interactions of human activities with natural sources and the landscape is critical to effectively managing water and sustaining water availability in the future.

Total radium concentration less than 5 picocuries per liter Total radium concentration greater than 5 picocuries per liter Total radium concentration less than 5 picocuries per liter Total radium concentration greater than 5 picocuries per liter

Understanding the Connection Through Examples

This document highlights several case examples and pres ents selected recommendations for increasing our understanding of the connections between water use and management, water quality, and availability.

Agricultural Practices Enhance Ground-Water Concentrations of Naturally Occurring Radium in Southern New Jersey

Concentrations of total radium in the Kirkwood-Cohan sey aquifer system underlying southern New Jersey exceeded the U.S. Environmental Protection Agency (USEPA) drink ing-water standard of 5 picocuries per liter in water from about one-third of the 170 wells sampled by the U.S. Geological Survey (USGS) in the late 1990s (Szabo and DePaul, 1998). (This standard, also referred to as the Maximum Contaminant Level, or MCL, is USEPA’s maximum permissible level of a contaminant in water delivered to any user of a public water system.) Some of the highest concentrations of total radium were in or near agricultural areas overlying the Bridgeton Formation where the ground water is acidic (pH less than 5). USGS findings suggest that agricultural practices, including use of lime and fertilizers, have modified ground-water chemistry and created an environment that increased the mobility of the naturally occurring radium within the aquifer. The MCL was exceeded more frequently in water from domestic wells than in water from public-supply wells sampled in the USGS study. The results may differ in large part because public-supply wells typi cally are distant from agricultural areas, tap relatively deep parts of the aquifer not as affected by activities on the land surface, and draw water from relatively large areas associated with large pumping volumes.

Naturally occurring chemicals that are considered contami nants in domestic well waters are not limited to New Jersey. For example, USGS studies show that concentrations of radon exceeded the proposed USEPA alternative MCL of 4,000 pico curies per liter in water from about one third of the domestic wells sampled in crystalline aquifers throughout New England (Ayotte and others, 2007). Arsenic, also naturally occurring, is elevated in water from domestic wells in selected areas across the United States, exceeding the MCL of 10 parts per billion in about 7 percent of wells sampled by the USGS. Some of the highest concentrations—a maximum of about 240 parts per billion—were found in the High Plains aquifers in Nebraska and Texas and in the Basin and Range aquifers in Arizona (McMahon and others, 2007; L.A. Desimone, U.S. Geological Survey, written commun., 2008). Concentrations differed across the country, owing to a combination of natural features, such as the presence of pyrite and other sulfide minerals, iron oxides, thermal water, and evapotranspiration (Welch and others, 2001).

Ground-Water Development Mobilizes Naturally Occurring Uranium to Public-Supply Wells in the San Joaquin Valley, California

In the past 10 years, elevated concentrations of dissolved uranium exceeding the USEPA MCL of 30 parts per billion have necessitated the removal of at least 14 public-supply wells from service in the eastern San Joaquin Valley of California. Uranium occurs naturally in soils and aquifer sediment derived from Sierra Nevada granitic rocks. USGS studies show that agricultural and urban development has increased pumping, as well as modified natural ground-water chemistry by enriching the ground water with dissolved oxygen and increasing alkalin ity. Together, an environment was created in the San Joaquin Valley that promotes the leaching of uranium from sediments as water recharges the land surface and moves to the aquifer system, ultimately affecting the deeper parts of the aquifer used for public supply (Jurgens and others, 2005).

Withdrawals Enhance Saltwater Intrusion in Coastal Areas in the United States

In numerous coastal areas, large drawdowns in pump ing wells cause adjacent or underlying saltwater to move into the freshwater system and affect the salinity of water supplies. Examples include Los Angeles and Orange Counties in Califor nia; Jacksonville, Tampa, and Miami, Florida; and coastal coun ties of New York and New Jersey. For example, as pumping in the Old Bridge aquifer underlying Union Beach Borough, New Jersey, caused ground-water levels to decline below sea level, saline water moved landward and concentrations of chloride and dissolved solids increased. As a result, pumping was curtailed in the 1980s, and the wells were abandoned in the early 1990s, replaced by wells farther inland (Alley and others, 1999; Barlow, 2003).

Pumping Induces Movement of Pesticides from Streams to Public-Supply Wells in the Midwest

In midwestern communities, high-capacity water-supply wells commonly are completed in the relatively permeable, unconsolidated sediments called alluvial deposits adjacent to large streams and rivers. Pumping can affect the movement of water between the alluvial aquifer and streams, and chemi cals that are applied to farmland and transported in runoff can ultimately affect the quality of ground water used for drinking. In the Great Miami and Little Miami River basins in southwest Ohio, for example, USGS studies show that at least one pesti cide was detected in 60 percent of samples from public-supply wells (about 80 feet deep). In this case, high pumping rates, as well as permeable streambed sediments and aquifer materials, have caused stream water to move into the ground-water system, sometimes reaching the wells in weeks or even days (Rowe and others, 2004).

Near Cedar Rapids, Iowa, pumping from public-supply wells has induced infiltration from the Cedar River, allowing contaminants to enter ground water. These contaminants often include pesticide breakdown products, which are forms of par ent chemicals after transformation through natural processes. On average, nearly 85 percent of the total pesticide concentra tion in stream samples was composed of 10 breakdown prod ucts of agricultural herbicides, including acetochlor, alachlor, atrazine, cyanazine, and metolachlor. As a result, Cedar Rapids officials are pursuing additional research and monitoring of breakdown products and parent pesticide compounds in ground water used for city water supplies (Kalkhoff and others, 2000).

Re-use of River Water Affects Ground-Water Quality Underlying Coastal Basins of Southern California

The Santa Ana River is an example of a highly engineered system in which water re-use affects the movement of water over the land and in the subsurface, ultimately affecting the quality of water used for public supply. In this basin, surface and ground water are cycled twice before being discharged to the ocean. In the first cycle, tributaries exiting the San Gabriel and San Bernandino Mountains are diverted to ground-water recharge facilities in the Inland Basin, where ground water is later extracted for use and then discharged as treated waste water to the Santa Ana River. In the second cycle, flow in the Santa Ana River is recharged to coastal aquifers. The artificially recharged water accounts for about three quarters of the water pumped from the coastal aquifer system (about 270 million gal lons per day), and contributes water used for public supply for nearly 5 million people living in the Santa Ana Basin.

The large-scale pumping and recharge in the coastal basins have accelerated the flow of ground water and increased the transport of man-made compounds in ground water. The pres ence of tritium, an indicator of ground water recharged since the early 1950s, was common in USGS water samples, indicat ing widespread replacement of older, native ground water with water recharged during the past 50 years. Other man-made compounds, including chloroform, which is a byproduct of water treatment for disinfection, also were widely distributed in the aquifer system (although remaining below USEPA drinking-water standards). The findings indicate that highly engineered systems in which water is re-used and exchanged between surface and ground-water systems can influence water in the future—in this case, today’s surface water affecting tomorrow’s ground water (Belitz and others, 2004).

Water managers utilize the flow of the Santa Ana River for recharging coastal aquifers. An inflatable rubber dam across the Santa Ana River impounds water to facilitate diversion into recharge ponds (Belitz and others, 2004).

Natural Factors and Human Activities Affect Salinity in the Southwest

USGS findings document the variability of salinity (dis solved solids) in streams throughout the Southwest—from 22 to 13,800 milligrams per liter. A USGS study using geostatistical modeling shows that both natural factors and human activities affect the degree of salinity in streams. Specifically, land-use practices and irrigation associated with pasture and cultivated land contribute more than half (56 percent) of the salinity to streams, whereas natural geologic materials provide the remaining 44 percent. The study also shows that the amount of dissolved solids that is transported and reaches streams varies considerably throughout the area, controlled in large part by water-use and agricultural activities, hydrology, and geology (Anning and others, 2007).

Understanding where salinity transport and accumulation occur is critical to identifying watersheds primarily responsible for delivering salts to the Colorado River and its tributaries. Water managers, policy makers, drinking-water suppliers, and scientists throughout the region are using the results of USGS studies to implement and evaluate various salinity-control and water-management strategies throughout the Colorado River Basin. For example, the Colorado River Basin Salinity Control Program, a successful cooperation among local, State, and Fed eral agencies, set an overall goal to cost-effectively reduce the amount of salinity in the Colorado River Basin. Salinity control projects, which involve low water-use irrigation systems and re direction of saline water from streams, have been implemented since the mid-1970s by the Bureau of Reclamation (BOR), U.S. Department of Agriculture, and the Bureau of Land Manage ment to control salinity of water per the 1974 Colorado River Basin Salinity Control Act (http://www.usbr.gov/uc/progact/salinity/).

USGS findings show that salinity decreased from 1989 through 2003 at all sites downstream from salinity-control projects, mostly located in the upper parts of the Colorado River Basin. For example, estimated annual loads of dissolved solids decreased by about 160,000 tons per year (or 14 percent of the annual load) downstream from the salinity-control unit on the Gunnison River. Decreases downstream from other projects ranged from about 4 to 11 percent of the annual loads. The con tinued, long-term decreases in salinity in the upper parts of the Colorado River Basin have resulted in salinity levels well below established goals at sites in or adjacent to the Lower Colorado River, including below Hoover and Parker Dams, and above Imperial Dam. On the basis of a BOR salinity damage model, the economic benefit of the decreases are estimated to be about $230M per year, in large part related to diminished damages to crops and crop yields (U.S. Department of the Interior, 2005).

Recommended Actions

The examples herein illustrate how water use and manage ment practices, together with natural features and the landscape, can affect water quality, and thus the availability of water for critical uses. As addressed by the Subcommittee of Water Avail ability and Quality (SWAQ), under the National Science and Technology Council, strategic investments in water science and technology can move the Nation forward in addressing some of these water availability challenges (National Science and Tech nology Council of the Executive Office of the President, 2007). SWAQ, which is made up of 25 Federal agencies responsible for Federal water research and (or) water-resource management, reports on a “coordinated, multi-year plan to improve research to understand the processes that control water availability and quality, and to collect and make available the data needed to ensure an adequate water supply for the Nation’s future.” Selected recommendations include the following:

• Continue to devise a national strategy, in partnership with State, regional, and local water agencies, for conduct ing a periodic inventory of the quantity and quality of the Nation’s water resources, water use, and water infrastruc ture.
• Continue to develop cost-effective water monitoring tech nology, such as sensors and systems to measure real-time water volumes and water quality, and develop standards and protocols for effective collection, management, and com munication of data.
• Develop innovative technologies to use water more effi ciently in the agricultural, energy, and industry sectors.
• Continue to improve understanding of water-related ecosystem needs by expanding monitoring, modeling, and research in ecosystem-based studies.
• Improve hydrologic models and their applications for deci sion-making at watershed scales. Inherent in model refine ment are improved ancillary data, such as on hydrology, geology, soils, climate, aquatic habitats, land-use changes, and chemical use.
• Support long-term data collection to provide an empirical basis for models and research needed to predict impacts of land-use change, water-use change, and climate change on the availability of water suitable for its intended uses.

References Cited

Alley, W.M., Reilly, T.E., and Franke, O.L., 1999, Sustainability of Ground-Water Resources: U.S. Geological Survey Circular 1186, 79 p. (http://pubs.usgs.gov/circ/circ1186/)

Anning, D.W., Bauch, N.J., Gerner, S.J., Flynn, M.E., Hamlin, S.N., Moore, S.J., Schaefer, D.H., Anderholm, S.K., and Spangler, L.E., 2007, Dissolved Solids in Basin-Fill Aquifers and Streams in the Southwestern United States: U.S. Geo logical Survey Scientific Investigations Report 2006–5315, 187 p. (http://pubs.usgs.gov/sir/2006/5315/)

Ayotte, J.D., Flanagan, S.M., and Morrow, W.S., 2007, Occur rence of Uranium and Radon in Glacial and Bedrock Aqui fers in the Northern United States, 1993–2003: U.S. Geologi cal Survey Scientific Investigations Report 2007–5037, 85 p. (http://pubs.er.usgs.gov/usgspubs/sir/sir20075037)

Barlow, P.M., 2003, Ground water in freshwater-saltwater environments of the Atlantic Coast: U.S. Geological Survey

cir1262)

Belitz, Kenneth, Hamlin, S.N., Burton, C.A., Kent, Robert, Fay, R.G., and Johnson, Tyler, 2004, Water Quality in the Santa Ana Basin, California, 1999–2004: U.S. Geological Survey

Jurgens, Bryant, Burow, Karen, Brown, C.J., Dubrovsky, N.M., and Stollenwerk, K.G., 2005, Elevated Levels of Naturally Occurring Uranium in Ground Water in Modesto, California: Geological Society of America Abstracts with Programs, v. 37, no. 7, p. 356.

Kalkhoff, S.J., Barnes, K.K., Becher, K.D., Savoca, M.E., Schnoebelen, D.J., Sadorf, E.M., Porter, S.D., and Sullivan, D.J., 2000, Water Quality in the Eastern Iowa Basins, Iowa and Minnesota, 1996–98: U.S. Geological Survey Circular 1210, 37 p. (http://pubs.usgs.gov/circ/circ1210/)

McMahon, P.B., Dennehy, K.F., Bruce, B.W., Gurdak, J.J, and Qi, S.L., 2007, Water-Quality Assessment of the High Plains Aquifer, 1999–2004: U.S. Geological Survey Professional Paper 1749, 136 p. (http://pubs.er.usgs.gov/usgspubs/pp/pp1749)

National Science and Technology Council of the Executive Office of the President, 2007, A Strategy for Federal Science and Technology to Support Water Availability and Quality in the United States, Report by the Subcommittee of Water Availability and Quality in the United States, September .2007, 35 p. (http://www.ostp.gov/galleries/NSTC/Fed%20ST %20Strategy%20for%20Water%209-07%20FINAL.pdf)

Rowe, G.L., Reutter, D.C., Runkle, D.L., Hambrook, J.A., Janosy, S.D., and Hwang, L.H., 2004, Water Quality in the Great and Little Miami River Basins, Ohio and Indiana, 1999–2001: U.S. Geological Survey Circular 1229, 40 p. (http://pubs.er.usgs.gov/usgspubs/cir/cir1229)

Szabo, Zoltan, and DePaul, Vincent, 1998, Radium-226 and Radium-228 in Shallow Ground Water, Southern New Jersey: U.S. Geological Survey Fact Sheet 062–98, 6 p. (http://pubs.er.usgs.gov/usgspubs/fs/fs06298)

rado River Basin Progress Report No. 22: U.S. Department of the Interior, 69 p. (accessed from http://www.usbr.gov/uc/progact/salinity/)

Welch, Alan, Ryker, Sarah, Helsel, Dennis, and Hamilton, P.A., 2001, Arsenic in Ground Water of the United States—An Overview: Water Well Journal, February 2001, p. 30–33.

Contacts

Robert Hirsch USGS Associate Director, Water (703) 648-5215 rhirsch@usgs.gov

Timothy Miller Chief, Office of Water Quality (703) 648-6868 tlmiller@usgs.gov

Donna Myers Chief, National Water-Quality Assessment (NAWQA) Program (703) 648-5012 dnmyers@usgs.gov

Pixie Hamilton Hydrologist, NAWQA (804) 261-2602 pahamilt@usgs.gov

Visit our Web site at http://water.usgs.gov/ to access publications, data, maps, and applications software.

• Access data on surface water, ground water, and water quality, which cover more than 1.5 million sites across the U.S., some of which are in “real time” (updated at intervals of 4 hours or less).
• Get up-to-date maps and graphs on streamflow con ditions through WaterWatch.
• Access technical reports and journal articles as well as publications that present broad overviews of key findings and their implications for resource manage ment, conservation, regulations, and policymaking at local, state, regional, and national levels.

Where this page came from

This page was imported from U.S. Geological Survey. Published by the U.S. Geological Survey and, as a work of the United States government, in the public domain.

Nobody has written it yet — it is the source material at a new address, which is why search engines are asked to skip it and why no one earns from it. It is up for grabs: take it on, and it is yours to rewrite and to earn from.