California's Contaminated Groundwater
Is the State Minding the Store?
Beneath the surface of the earth lies a vast body of water. It does not exist in a large underground lake or a flowing underground stream but rather as tiny droplets of water, interspersed among the grains of soil and rock that we commonly picture when imagining the world underground. Nevertheless, the aggregate volume of those tiny water droplets is greater than the volume of all the lakes and rivers of the world combined. In fact, the volume of groundwater is estimated to be more than 30 times the combined volume of all fresh-water lakes in the world and more than 3,000 times the combined volume of all the world's streams. In California alone, current supplies of usable groundwater are estimated at about 250 million acre-feet  -- six times the volume of all of the state's surface water reservoirs combined.
For more than 100 years, groundwater has provided a substantial and essential resource for California's agriculture, its industries, and its cities. It was not long after statehood in 1850 that California's residents began building pumps to extract this plentiful resource from the subsurface. The scarcity and seasonal availability of surface water, especially in the southern half of the state, have caused Californians to turn time and time again to the state's groundwater supply.
Indisputably, the availability -- and, more importantly, the deficiency -- of all forms of freshwater have substantially influenced California's history and development. In fact, water is widely considered the single most significant natural resource affecting the growth of the state. Given the arid climate that pervades most of the southern half of the state  and the limited supply of running water, legendary political and economic battles occurred over access to the waters of the Mono Basin, the San Joaquin River, the Owens Valley, the Colorado River, and the Sacramento-San Joaquin Bay Delta.
Yet despite their importance, these surface water bodies are only part of the water picture in California. Between 25 and 40 percent of California's water supply in an average year comes not from surface streams or reservoirs but rather from beneath the ground. That figure can be as high as two thirds in critically dry years. In fact, California uses more groundwater than does any other state. Californians extract an average of 14.5 billion gallons of groundwater every day -- nearly twice as much as Texas, the second-ranked state.
Fifty percent of California's population -- some 16 million people -- depends on groundwater for its drinking water supplies. But of course, groundwater is used for much more than just drinking water. California also leads the nation in the number of agricultural irrigation wells, with more than 71,000.  In the Lower Sacramento River Valley alone, approximately 750,000 acres of prime agricultural land are irrigated, at least in part, by groundwater. Indeed, many areas of the state rely exclusively on groundwater for their water supplies. In the lower Sacramento Valley, for example, approximately one million people rely on groundwater to supply all of their water needs.
For all of these reasons, the California Department of Water Resources has concluded that water from California's groundwater basins "has been the most important single resource contributing to the present development of the state's economy." Yet despite the importance of this resource, until relatively recently groundwater never received a degree of attention or protection commensurate with its value to society. Part of that failure may be due to ignorance. Until recently, groundwater was believed to be both naturally pristine and immune from contamination by surface activities.
We now understand that the quality of the water stored underground in aquifers (the geological formations that hold groundwater) is fragile. Groundwater resources can be effectively diminished if they become contaminated to such a degree that the water remaining in the aquifers is rendered unusable -- or requires expensive treatment in order to be made usable. Technological advances continue to make treatment a more viable option and may eventually permit the use of once-abandoned groundwater reserves, as we learn to remove more types of contaminants and at lower costs. However, at least for the foreseeable future, true groundwater remediation is generally a time-consuming and costly process.
Yet without remediation, most forms of contamination will persist and may even worsen. Unlike an aquifer suffering from depletion, which may rebound naturally during the next wet season without human intervention, a contaminated aquifer may remain contaminated (depending on the nature of the contaminants) for hundreds, or even thousands, of years. Furthermore, contaminants will inevitably spread -- albeit very slowly -- within any given groundwater basin. Finally, some lag time inevitably exists between the contamination of water and the discovery of that contamination, often with some further delay before the use of the contaminated water is terminated. Thus, contamination not only results in a reduction in the amount of immediately usable water, but may also result in human exposure to hazardous levels of contaminants.
For these reasons, the contamination of our groundwater resources is a serious, long-term threat to the viability of the resource in California, a state that relies on its groundwater for many purposes. Understanding the full extent of the problem, and generating reliable information on trends that can inform policy and resource allocation decisions, are the best, and indeed, most basic, approaches to safeguarding this natural resource. Surprisingly, the information that is available about the quality of groundwater in California, as well as water quality trends, is extremely limited -- and often unreliable. Perhaps not so surprisingly, existing information, including some of the most reliable data available, paints a picture of widespread groundwater contamination in California.
What Do Existing Statewide Data Tell Us?
The primary state assessment mechanism for determining the condition of the state's groundwater resources is a report produced by the State Water Resources Control Board, and updated every two years, known as the "305(b) Report." The most recent edition suggests that more than one third of the areal extent of groundwater in the state (a two-dimensional measurement of the surface area of the land under which groundwater basins are located) is contaminated to such a degree that it cannot safely be used for all of the purposes the state has designated as appropriate and desirable. According to the year 2000 update of the 305(b) Report, each of the five most prevalent and harmful classes of contaminants independently contributes to the impairment of more than 15 percent of the groundwater assessed in the state, as measured by surface area. Furthermore, the causes of this contamination are many and varied. Several major sources and activities continue to contribute to groundwater pollution, including septic systems, landfills, leaking underground storage tanks, and agricultural operations.
While existing data paint a picture of a significantly degraded natural resource, the incomplete and often fundamentally unreliable nature of this information is an equally significant problem. NRDC's investigation revealed that the 305(b) Report, for example, although ostensibly the most comprehensive and thorough analysis of the state's groundwater basins, is so seriously flawed that its groundwater data is of questionable value. The problems in the 305(b) Report's groundwater information range from data-collection inaccuracies to a lack of substantiation for basic assumptions.  Indeed, within a few days after NRDC provided the State Water Resources Control Board, the agency responsible for the 305(b) Report, with an advance copy of this NRDC study, the Board announced that even it did not consider much of its own groundwater data to be reliable. Although the Board has been publishing the same or similar data for nearly ten years without caveat, on March 22, 2001 senior Board staff wrote to NRDC and the federal Environmental Protection Agency and declared that the "State Water Resources Control Board (SWRCB) staff is retracting all groundwater assessment information from the SWRCB's year 2000 Clean Water Act (CWA) Section 305(b) report." This unprecedented action by the primary state agency charged with water quality control is indicative of the challenge facing California in attempting to understand the full extent of statewide groundwater contamination.
There are other agencies involved in collecting information about the quality of California's groundwater resources, but that is as much a part of the problem as a solution. Multiple agencies manage often competing monitoring and assessment systems, none of which is adequate on its own as a means of effectively assessing and protecting groundwater quality throughout California. Notwithstanding the good intentions of many state agencies, a failure to reform a highly fragmented and inefficient monitoring and assessment approach leaves California unprepared to assess and protect adequately this critical natural resource in the twenty-first century.
Findings and Recommendations
In order to characterize the condition of California's groundwater resources and the effectiveness of the groundwater monitoring and assessment system employed by responsible state agencies, NRDC searched for and reviewed available data on the condition of the resource and the sources of the most prevalent contaminants found within it; we also assessed the means by which this information is gathered. The data upon which NRDC relied came primarily from a variety of government agencies, at both the state and federal level. NRDC used that data, other information, and its own professional judgment, to derive a list of five significant and representative groundwater contaminants and their sources. We then analyzed each one in greater detail, based on the most comprehensive and reliable data available with respect to those specific contaminants and sources. Based on that research, NRDC found that:
Available information suggests significant contamination of California's groundwater basins. Specifically:
- According to questionable State Water Resources Control Board data, more than one third of the areal extent of groundwater assessed in California is so polluted that it cannot fully support at least one of its intended uses, and at least 40 percent is either impaired by pollution or threatened with impairment;
- Groundwater contaminants include both naturally occurring substances, such as some metals, and anthropogenic ones, such as pesticides. Salinity, organic compounds, pesticides, nutrients, and metals are among the most significant types of contaminants that threaten or impair groundwater basins in California;
- Large numbers of drinking water wells regularly exceed drinking water standards (with thousands of exceedances last year alone), necessitating various means of treatment prior to the delivery of water to users;
- Groundwater contaminants have been detected at levels that exceed applicable federal or state standards throughout many regions of California. Likewise, a variety of contaminants, reflecting a range of human activities and natural causes, threaten or impair groundwater basins in California.
There are several significant sources of that contamination:
- Leaking underground storage tanks, natural sources, agriculture, land disposal, septage, and industrial point sources are leading causes of groundwater contamination.
There is no comprehensive groundwater monitoring program in California -- and available information is often of dubious quality. Specifically:
- The status of California's groundwater resources is monitored by an array of different agencies (both state and federal) with little, if any, coordination among them;
- The format in which the information about groundwater quality is presented can be deceptive, in that agencies assess the quality of the water relative to certain standards (which may or may not be appropriate), rather than relative to its natural state or to previous measurements, thus obscuring the degree to which the water's composition has been altered and providing no data trends;
- Much of the general data, such as information generated by the State Water Resources Control Board about the scope of the state's groundwater impairment problem, is simply incomplete and/or unreliable, making it difficult to know for sure the condition of one of California's most important natural resources;
- Agencies that do collect reliable data, such as the Department of Health Services, the Department of Pesticide Regulation, and the U.S. Geological Survey, do not survey the groundwater basins throughout the state in a comprehensive manner from which conclusions might be drawn regarding the status of the resource as a whole. Based on the findings of this study, NRDC concludes that there are a number of reforms and improvements that need to be made at the state level in order for California to improve its stewardship of the quality and usability of its groundwater resources.
In particular, NRDC makes the following recommendations:
- The state agencies responsible for protecting and managing California's groundwater resources (particularly the State Water Resources Control Board, the Department of Health Services, and the Department of Water Resources) should improve the scope and quality of their information by instituting a more systematic and ongoing monitoring program and by standardizing the formatting of the data gathered;
- A single agency should be responsible for compiling all of the information and for making that information readily accessible to the general public;
- The significant inadequacies and errors contained in the 305(b) Report should be remedied through a complete reformation of this critical statewide groundwater assessment;
- The agency or agencies responsible for protecting California's groundwater resources and the health of California's residents should develop a better understanding of the actual contaminants that are affecting the groundwater and the sources from which they come;
- The Legislature should ensure that adequate funding is provided to support these programs;
- The Legislature should ensure adequate implementation and enforcement of prevention programs to prevent further contamination of groundwater resources;
- The agency or agencies responsible for remediation of contamination within groundwater basins should ensure timely remediation of already contaminated sites;
- The Legislature should institute "polluter pays" provisions for groundwater contamination to compensate the individuals or agencies conducting remedial activities. However, it should clearly provide that remediation is not to be contingent upon identification of the responsible parties and that collection of compensation is not to be a prerequisite to remedial action.
1. Ground Water, U.S.G.S. General Interest Publication, (Jan. 5, 2001) http://capp.water.usgs.gov/GIP/ gw_gip/gw_a.html, 2/27/01.
2. An acre-foot is the amount of water that it takes to cover an acre of land to a depth of one foot. It is equivalent to 325,851 gallons.
3. The current capacity of California's surface water reservoirs is about 43 million acre-feet. Ground Water Report to Congress, Ground Water Protection Council, (Oct. 1999), p. 9.
4. California's Ground Water, Department of Water Resources Bulletin No. 118, DWR (1975), p. 3 (concluding that groundwater has contributed to the development of the State's economy more than any other resource).
5. In fact, most of the state has a semi-arid climate. Ground Water Quality and its Contamination from Non-Point Sources in California, UC Davis Centers for Water and Wildland Resources (June 1994), p. 1.
6. Of course, water scarcity is not unique to California. Hinrichsen, D., B. Robey, and U.D. Upadhyay, "Solutions for a Water-Short World," Population Reports, Series M, No. 14, Johns Hopkins University School of Public Health, Population Information Program, Baltimore, Maryland, (1998), found that thirty-one countries were facing water stress or water scarcity and predicted that, by the year 2025, "35 percent of the world's projected population of 8 billion people [and 48 countries] will face water shortages." Water Experts call for Blue Revolution.
7. State Water Resources Control Board Strategic Plan (SWRCB, July, 1997) p. 9; California's Ground Water, Department of Water Resources Bulletin No. 118 (DWR, 1975) p. 3 and p. 7. WEF's Calif. Water Issues Briefing says 30% (3/10/99) ("WEF website") p. 13; see also California Water Facts Groundwater p. 1; "Ground Water Report to Congress" (says 40%); also (160-98) pp. 3-48 (30%) "25-40 percent of the state's usable water supply in normal years and up to two-thirds in critically dry years."
8. California Water Issues (3/10/99) p.14, http://www.water-ed.org/ california.asp#waterissues. (update -- see chap. 2).
9. FAQs and Ground Water Facts, National Ground Water Association (May 20, 1999), www.ngwa. org/gwmarket/faqs.html, 11/17/00.
10. Ground Water Report to Congress, Ground Water Protection Council, (Oct. 1999), p. 9.
11. FAQs and Ground Water Facts, National Ground Water Association (May 20, 1999), www.ngwa. org/gwmarket/faqs.html, 11/17/00.
12. Groundwater: The hidden water supply, California Department of Water Resources, (1997), http:// well.water.ca.gov/gwbrochure/, 2/27/01, pp. 4-5.
13. California Water Facts Groundwater, p. 1.
14. Groundwater: The hidden water supply, California Department of Water Resources, p. 3.
15. California's Ground Water, p. 3.
16. See, e.g., 2000 California 305(b) Report on Water Quality, State Water Resources Control Board (Oct. 2000).
17. These numbers are not necessarily additive, as different classes of contaminants may contaminate the same water body. Thus, it is not necessarily true that 75% of the groundwater in the state (5 x 15%) is impaired.
18. In addition to all the other problems with the data, as indicated above, the results of the State Water Resources Control Board's analysis of the scope of contaminated groundwater in California are present in two-dimensional figures, while groundwater exists in three dimensions.
19. Letter from Stan Martinson, Chief, Division of Water Quality, State Water Resources Control Board, to Janet Hashimoto, U.S. EPA Region IX, Bill Vance, Cal/EPA, and Alex Helprin [sic], NRDC (Mar. 22, 2001). This letter is reproduced in full in the sidebar on page 15 ("Disappearing Data").
Sign up for NRDC's online newsletter
Water on Switchboard
NRDC experts write about water efficiency, green infrastructure and climate on the NRDC blog.
Recent Water Posts
- Illinois' Water Plan: How to Prepare for a Warmer, More Flood-Prone Climate
- posted by Peter Lehner, 7/23/14
- Building Climate-Resilient Communities with State Revolving Funds
- posted by Ben Chou, 7/23/14
- Small Business Owners Want Clean Water Protections
- posted by Karen Hobbs, 7/23/14
NRDC Gets Top Ratings from the Charity Watchdogs
- Charity Navigator awards NRDC its 4-star top rating.
- Worth magazine named NRDC one of America's 100 best charities.
- NRDC meets the highest standards of the Wise Giving Alliance of the Better Business Bureau.