|
Groundwater Quality
Ground water resources in Nevada are precious. Cleaning up groundwater once contaminated is extremely costly and can take years. Before beginning activities that could contaminate groundwater, a permit must be obtained from the Bureau of Water Pollution Control. Strict regulations require implementation of preventative measures and monitoring. Preventative measures include holding tanks, impermeable liners, wastewater pretreatment, and using products or processes that do contain fewer or no potential contaminants. Monitoring helps identify undesirable water quality changes and prevent larger problems.
Because the purposes for monitoring groundwater quality vary, responsibilities are divided among different agencies. The Bureau of Health Protection Services, part of the Nevada Health Division, monitors aquifers tapped to supply public water systems. The Nevada Department of Agriculture (NDOA) shares responsibility for pesticides monitoring with NDEP. In addition, NDEP monitors groundwater quality through a permit program for facilities and activities that discharge, or may discharge, pollutants to groundwater. An important federal partner is the U.S. Geological Survey (USGS). The USGS conducts special studies and long term monitoring programs, often in conjunction with state agencies.
Monitoring is critical because early warning of changes in quality can avoid decades of treatment or abandonment of aquifers. Declining quality can result from natural, man-caused, or a combination of natural and human sources. Natural pollutants of concern include arsenic, radon, total dissolved solids, and metals.
 |
| Photo of Fly Geysers north of Gerlach. The tufa formation gets is unique color form living thermophillic algae that began growing in the 1960's when the geyser was caused by geothermal exploration: Source -- Reno Gazette Journal |
Certain land disturbing activities may disturb geologic or soil formations and mobilize natural contaminants, such as mining sulfide rich metal deposits, or concentrate them in specific areas, such as irrigation drain water. Problematic groundwater contaminants are released from residential, agricultural and industrial sources. Contaminants of greatest concern include pesticide/herbicide contamination, solvents and petroleum products, radioactive materials, metals, dissolved salts, and nitrogen.
Like surface water, the biggest groundwater quality protection challenges derive from less obvious, widespread pollution sources. Numerous diffuse sources of petroleum chemicals, solvents, metals, nutrients, dissolved salts, pesticides and pathogenic bacteria occur in urban, suburban, farming, mining, and industrial areas. In general, higher groundwater quality occurs in rural areas and lower quality in urban and suburban areas.
The most frequently encountered mineral contaminant is nitrates, typically associated with high septic tank density, concentration of livestock in feedlots or low-density subdivisions, and fertilizer application for turf and certain crops. Solvents, such as perchloroethylene (PCE), and gasoline byproducts are the most common chemical constituents in degraded groundwater. Federal and state underground storage tank replacement and monitoring programs have greatly reduced the likelihood of leaks, thereby reducing accidental spills.
Groundwater Quality Status
In general, all groundwater bodies are considered to be a potential source of drinking water. The federal Safe Drinking Water Act standards, called Maximum Contaminant Levels, are applied when evaluating potential impacts of different pollutant sources and setting remediation or clean-up levels (Nevada Division of Environmental Protection, 1998b).
Though substantial groundwater quality monitoring is conducted by various agencies, these data are not managed in a statewide database. The U.S. Geological Survey National Water-Quality Assessment Program (NAWQA) recently published a comprehensive groundwater quality assessment report.
The NAWQA study area in Nevada includes the Las Vegas Valley area, the Carson River Basin, and the Truckee River Basin. These basins were selected for an intensive sampling and assessment project because they contain more than 90 percent of Nevada's population; rapid population growth has increased competition for limited water supplies; and, natural and human-caused water-quality problems are evident (U.S. Geological Survey, 1998).
A number of important groundwater quality findings were reported in the study. Many of the shallow monitoring wells and deeper water supply wells sampled in urban areas contained low levels of pesticides and volatile organic compounds. However, pesticide occurrences in shallow wells located in agricultural areas were lower than in the urban areas. Similarly, sampling of shallow wells in agricultural and urban areas showed that the latter contained higher levels of nitrates. Some urban shallow wells contained nitrate levels exceeding the safe drinking water standard. Deeper supply wells tested contained elevated nitrate concentrations, but all were below the standard of 10 milligrams per liter. The significance of these findings is that shallow water-table aquifers can be linked to deeper drinking water aquifers.
The incidence of elevated nitrate levels in aquifers underlying suburban and rural subdivisions has increased. New homes and businesses built outside urban areas often use individual septic systems, which at the time of construction appear to be a cost effective alternative to community wastewater treatment systems. In some valleys, septic systems have become concentrated, especially where piecemeal (parcel map) subdivision development is allowed.
Of special concern are subdivisions on septic systems that use local groundwater sources for domestic or community drinking water supply. A study of groundwater beneath un-sewered subdivisions in valleys north of Reno found that contaminant plumes expand rapidly when the combined domestic well pumpage exceeds annual groundwater recharge. The study suggested that septic system seepage was a major source of recharge and was contributing to elevated nitrates. In the studied valleys, 20 percent of the 250 sampled domestic wells contained water near or above the nitrate drinking water standard (Washoe County Department of Public Works and Desert Research Institute, circa 1995).
Elevated nitrate levels have been found in shallow groundwater bodies underlying twenty-three residential subdivisions (Nevada Division of Environmental Protection, 2001b). Currently only six communities are known to have public supply wells with elevated nitrates, and only two of these have had to take actions that reduce nitrate levels because the drinking water supply standards were exceeded (Nevada Division of Environmental Protection, 2001b).
Domestic well quality data is not compiled by state agencies, but homeowners are advised to have domestic well water analyzed periodically at a certified lab. Alternative solutions to the problem of high nitrate levels in groundwater include closure of individual septic systems with connection to community wastewater treatment systems; switching from a domestic well supply source to a public water supply system; or, pumping groundwater for irrigation uses to contain the zone of high nitrates. Cooperation between state, local, and property owners is necessary to improve impaired groundwater supplies in suburban and rural communities.
Well Head Protection
As more homes and businesses rely on groundwater, pollution prevention has become increasingly important. In 1994, the Division of Environmental Protection set up the Wellhead Protection Program (WHPP) that gives local communities technical guidance for long-term drinking water source protection. Though not required, many communities already have prepared local WHPP's. The wellhead protection framework involves identifying the land surface area that should be managed to protect the groundwater being pumped; inventorying and mapping existing and potential contaminant sources located within that area; and, selecting appropriate management strategies.
Common potential contaminant sources include underground storage tanks, improperly abandoned wells, improperly applied fertilizers and pesticides, and high concentrations of septic systems. Management options might include regulations such as zoning ordinances, or non-regulatory options such as public education. A WHPP also can include plans for dealing with emergencies or accidental contaminant releases. Because pollutants come from many smaller sources (e.g., residential lawns, commercial parking lots, and individual septic systems) that are difficult to oversee, public education and participation is a critical element of WHPP.
Since 1994, 27 water systems or communities have prepared wellhead protection plans. This number is projected to increase to 32 during 2001 (Bureau of Water Quality Planning, 2001). The program is voluntary, so data is not available on the number of communities that have progressed with plan implementation. Implementation challenges include limited local government funds, additional public and private costs, and concern that limitation might be placed on land uses within a wellhead protection zone.
Underground Injection Control
The Underground Injection Control (UIC) Program is another federal program for which the State of Nevada has accepted responsibility. The goal of the program is to protect Nevada's groundwater resource from potential degradation by the injection of fluids into a well.
 |
| Geothermal energy is used at Empire Farms to process garlic and onions, in addition to generating electricity. The photo shows the pond and drying facility in the background. Photo courtesy of Larry Garside, Empire Farms. 2001 |
Injection of fluids is allowed for various purposes. One is injecting water to boost groundwater supplies, known as Aquifer Storage and Recharge (ASR). Nevada's UIC program regulates the injection of fresh, potable water into drinking water aquifers where it is stored for use at a later date.
Fluids also are injected for groundwater remediation. Contaminated water can be pumped, treated, and then returned to the aquifer. Another type of injection activity introduces nutrient enriched fluid into a polluted aquifer to stimulate bacterial decomposition of the contaminants. Biodegradation is a prominent means of re-establishing the beneficial use of groundwater where oil, gas and petroleum byproducts have leaked or spilled.
Nevada's geothermal resources (State Map PDF 1.9MB), used for electricity generation, space heating, and industrial processes, are regulated under the UIC program. After use, the spent geothermal fluid is re-injected into the aquifer of origin, where feasible. Care must be taken to avoid both contamination of adjoining aquifers with higher quality water and accelerated cooling of the natural reservoir of hot or warm water. Open pit mines that dewater and then return groundwater to the aquifer are also covered under the UIC Program.
Leaking Underground Storage Tanks, Spills, and Brownfields
Contaminated properties most often involve industrial or commercial activities that have released chemicals. Nevada law requires owners to report contamination events to the state Division of Environmental Protection (NDEP) and to take necessary remedial action at the site. The most serious long-term clean up projects occur where contamination moves through the soil and contaminates groundwater. Leaking underground petroleum storage tanks are responsible for most of the cleanup sites in Nevada. To comply with state administered regulations established under the federal Resource Conservation and Recovery Act, older tanks were to have been removed or upgraded by December 1998. Each year, fewer contaminated sites are being found, and more sites are being cleaned up. Consequently, the number of open sites with ongoing corrective action is declining.
The Petroleum Fund and the Underground Storage Tank/Leaking Underground Storage Tank (UST) Programs provide incentives and regulatory oversight for cleanup activities. The programs are implemented by the Bureau of Corrective Actions, which operates under regulations requiring cost benefit evaluations prior to clean up actions. In fiscal year 1999, the Bureau opened 88 new Petroleum fund cases, closed 191 cases, and disbursed approximately $ 4.98 million in Petroleum fund monies. In fiscal year 2000, 60 new cases were opened, 3 were closed, and $ 6.04 million dollars were disbursed (Nevada Division of Environmental Protection, 2000).
Since the 1992 inception of a formalized remedial action program, approximately 1,097 non-UST sites have been investigated and cleaned up to State requirements. These cases involved petroleum products, heavy metals, organic compounds, pesticides and PCB's. Approximately 125 cases are open and active at any given time.
Remediation efforts continue in Washoe County to investigate the extent of ground water contamination by cleaning solvents in Downtown Reno. Monitoring activities indicate the need for additional remediation efforts, which are underway. Sampling was conducted near the Yerington mine project to determine if the mine has impacted any down gradient municipal or private wells. Sampling results indicated that there were no impacts on these wells. Cleanup activities at the Rio Tinto mine in northern Elko County are continuing. Major cleanup efforts at the BMI industrial complex in Henderson have begun to remediate contamination and turn the site into a master planned community.
About 500 spills are reported annually. More than half occur in the heavily populated southern and western part of the state. Prompt cleanup of hazardous substance spills reduces danger to public safety and prevents spill sites from becoming contaminated properties. Most spills are small. While quantity can be important, the properties of the substance spilled and the location of the spill are generally more critical factors. The most common substances spilled are petroleum products. Nearly 75 percent of all spills impact the soil. Excavating the contaminated soil and refilling with clean soil usually cleans up these spills. When a spill impacts surface water or groundwater, it presents a greater risk and requires a more intensive response.
 |
| This is the remediation system located near the fuel terminal tank farm in Sparks, Nevada |
State and federal environmental protection agencies are teaming up to accelerate the clean up of contaminated lands. The Brownfields Program applies to contaminated property that has been abandoned or under-used. Putting these brownfield properties back into productive use returns them to the tax base, brings jobs to populated areas, and helps conserve other land for farming, recreational areas, and green space. The NDEP-operated program advises property buyers and sellers, local governments, lenders, and developers about legal and technical options that will get the cleanup done and help ensure that land development does not hopscotch around the brownfield sites. Advanced monitoring and contaminant transport modeling technologies will be used by NDEP that raise the certainty that remediation of a contaminated site has been successful.
The Nevada State Legislature in 1999 passed the Program for Voluntary Cleanup of Hazardous Substances and Relief From Liability. The purpose is to encourage voluntary cleanup of contaminant releases and remove the stigma of potential liability for future landowners and lenders. The Voluntary Cleanup Program will result in clearing the pathway for returning these properties to beneficial use in a timely and efficient manner.
Drinking Water Supply
Chances are great that the tap water you use for drinking and domestic purposes comes from a public water system. In 1999, 97 percent of Nevada's citizens were served by one of 670 public water systems. Public water systems can be small, with as few as 15 connections or 25 people, or large, serving hundreds of thousands of people. Cities, towns, casinos, campgrounds, restaurants, schools, mines, and factories are served by public water systems.
Ensuring that water delivered by public systems meets drinking water standards is vital to the public health, welfare, and economy. Reducing outbreaks of waterborne disease and chemical poisoning, and increasing the proportion of people who receive a supply of drinking water that meet Safe Drinking Water Act standards established by the U.S. Environmental Protection Agency (EPA), are two of the Department of Health and Human Services' objectives.
EPA has set drinking water maximum contaminant levels (MCL) for 90 substances, establishing safe limits for public water supplies. However, many contaminants in drinking water have no MCL's. Furthermore, combinations of chemicals in drinking water can have health impacts that are not well understood yet. As a result, preventing contamination of sources of drinking water supply is a critical concern. Public water system operators must monitor drinking water for microbiological and chemical contaminants regulated under the Safe Drinking Water Act (SDWA) to ensure drinking water standards are not exceeded. Monitored chemicals include nitrogen compounds, metals, pesticides, solvents, petroleum byproducts, and radon. As a precautionary measure, drinking water in Nevada is monitored for about 50 additional organic chemicals for which standards have not been set.
When a public water system violates a drinking water standard, it must notify the public, identify the source of the problem, take necessary corrective action and resample. Public water systems in Nevada have done well in providing clean water. In 1999, seven public water systems generated seven chemical violations (arsenic, antimony and nitrate) and 71 systems generated 89 microbial violations, only three of which were acute. Of the 670 public water systems in the state, 89 percent reported no contaminant levels that exceeded the standards (Nevada Health Division, 1999).
Wastewater Treatment and Reuse
The ground water and surface water discharge program administered by the NDEP plays a leading role in protecting the quality of Nevada's natural water supplies. The Bureau of Water Pollution Control issues permits for the discharge of treated wastewater (sewage) under the state groundwater protection program and National Pollution Discharge Elimination System (NPDES) program. The U.S. Environmental Protection Agency (EPA) delegated responsibility for the NPDES program to Nevada. The discharge of treated wastewater to surface waters is regulated through pollutant limits in discharged water, best available treatment technology guidance, monitoring, and reporting.
Similar to the NPDES program, the state groundwater protection program protects the quality of underground aquifers through a permitting and inspection system for treated wastewater discharged into rapid infiltration basins and evaporation ponds. The reuse of highly treated wastewater (reclaimed water) for irrigation is another type of discharge to groundwater that has become more common. Properly treated and applied, reclaimed water is a safe and economical irrigation alternative to using limited groundwater and surface water supplies. An environmental benefit of using reclaimed water for irrigation is the reduction in pollutant discharges into Nevada's rivers and lakes. The number of permits in effect for reclaimed water uses reached sixty-five in 2000. An applicant proposing to use reclaimed water must submit an effluent management plan (EMP) which details how the reclaimed water will be applied to the site. The EMP lists health safeguards for irrigation and application rates. Health safeguards include aerosol drift controls, public notification, and protection of water supplies.
Reclaimed water is applied throughout the state for irrigation of parks, golf courses, and agricultural lands. Other uses of reclaimed water include dust control on unpaved roads and construction sites, soil compaction, and power plants. In Carson Valley, treated wastewater piped from communities in the Lake Tahoe Basin supplies water for wetlands and agricultural uses. In some circumstances, a new use of reclaimed water for irrigation results in less water returned to a surface water body. Any beneficial use of reclaimed water requires two permits from the State Engineer: a primary permit on the source (i.e., waste water treatment facility) and a secondary permit for the beneficial use.
 Next Page -- Wastes and Environmental Contaminants
Back to Table of Contents
|
|
Related Information: