Kesterson Reservoir | |
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Location | Merced County, California |
Coordinates | 37°15′30″N120°53′30″W / 37.25833°N 120.89167°W |
Type | reservoir |
The Kesterson Reservoir is part of the current San Luis National Wildlife Refuge in California. Formerly a unit of the Kesterson National Wildlife Refuge, the reservoir was an important stopping point for migratory waterfowl. [1] Kesterson once consisted of 12 evaporation ponds totaling approximately 1,280 acres, [2] and was historically used for agricultural drainage. Kesterson gained national attention during the latter half of the 20th century due to selenium toxicity and rapid die off of migratory waterfowl, fish, insects, plants and algae. The reservoir was closed in 1986, and concentrations of selenium at the site have continued to be monitored throughout remediation efforts.
The Kesterson National Wildlife Refuge is located approximately 18 miles west of Merced County in the San Luis National Wildlife Refuge, in the San Joaquin Valley of central California. [1] The refuge is 26,609 acres (107.68 km2) and includes a variety of wetland and riparian habitat which supports a large variety of waterfowl, mammals and other wildlife across four units, the Kesterson Reservoir, Freitas, Bear Creek and original San Luis Units.
The San Joaquin Valley, considered by historian Kevin Starr as "the most productive unnatural environment on Earth", [3] supports approximately 25% of the United States’ agricultural products including grapes, cotton, nuts, citrus, and vegetables. [4] Cattle and sheep ranching also contribute to the agricultural output of the area. The valley grew rich in phosphoric acid during prehistoric times, when as an inland lake it provided a habitat for clams. The accumulation of these shells made the land rich in phosphoric acid.
The San Joaquin Valley is bordered on the west by the Coast Range and on the east by the Sierra Nevada mountains. The Coast Range include Cretaceous and Tertiary marine sedimentary rocks. [5] Weathering and oxidation of the Moreno Formation, a black marine shale, produces Pyrite, FeS2, and Iron Selenide, FeSe2. As the weathered products concentrate in evaporative minerals and salts, selenates [6] (for instance, Na2SeO4 · 10 H2O or Na2Mg(SeO4)2 · 4 H2O) and Sulfates (Na2SO4 · 10 H2O or Na2Mg(SO4)4 · 4 H2O) can form. This results in selenium salts and selenium rich soils that are sloughed off the mountains via debris flows or landslides into the San Joaquin valley. Additionally, the San Joaquin Valley has a shallow aquifer bounded by impermeable clays. [7]
Large-scale agricultural production relies on similarly large-scale irrigation projects in order to keep fertile farms in operation. A side effect of irrigation in the San Joaquin Valley was that ground water levels began to rise over time. This led to a condition where excess water was accumulating and harming crops. In 1968, the Bureau of Reclamation proposed a 290-mile long drainage canal, called the San Luis Drain. [8] As part of the large drainage canal the Kesterson Reservoir, which consisted of 12 evaporation ponds, was completed in 1971 within the Kesterson National Wildlife Refuge.
In 1985 Kesterson Reservoir was issued an abatement order to close by the California State Resources Control Board due to the 1983 discovery of a 64% rate of deformity and death of embryos and hatchlings of wild aquatic birds. [12] According to the USGS, the high deformity and death rates were a result of selenium contamination traced through irrigation drainage and sourced to the bedrock of the California Coast Ranges. [12] The USGS defined the biogeochemical pathway of selenium moving "from rock to duck” as the 'Kesterson effect". [13] The group of symptoms and effects observed in birds from research at Kesterson Reservoir is known as "Kesterson Syndrome". [14]
Selenium is a naturally occurring element in the environment, and is an essential dietary nutrient. However, in high concentrations, selenium bioaccumulates to toxic levels in tissues and can cause reproductive failure and birth defects, or deposit in sediments. [15] Due to the concentration of selenium in the Coast Range west of the San Joaquin Valley, selenium was transported into the valley and naturally accumulated on the valley floor. Selenium toxicity became a problem shortly after drainage tiles were installed at Kesterson. Initially (from 1971 to 1978), the reservoir received only fresh water. In 1978 this began to change and by 1981, all water coming into the Kesterson Reservoir was saline drainage water. Contributing to the salinity of the drainage water was the highly-mobile ion of selenium, selenate, SeO42−. In 1983 selenium concentrations, primarily in the selenate form, were about 300 μg/L. From 1981 to 1986 about 9000 kg of Se were delivered to Kesterson. [2] Concentrations of selenium in the reservoir increased steadily as the drainage water evaporated from the 12 evaporation ponds. [1] Selenium began to bioaccumulate in the waterfowl and wildlife that used the reservoir.
Prior to 1981, the Kesterson Reservoir supported a wide variety of life, including several species of fish. After 1981, the reservoir only supported the most saline tolerant mosquito fish. In 1982, the United States Fish and Wildlife Service began a study to determine the cause for declining wildlife use at the reservoir. Selenium concentrations at these locations were found to be greater than 1400 micrograms per liter. Mosquito fish samples from 1982 showed that fish from the Kesterson Reservoir contained selenium concentrations more than 70 times higher than fish sampled from a nearby reference site. [16]
In 1983, researchers investigated the prevalence of selenium in the diets and tissues of the birds of the Kesterson Reservoir. [9] The study found that selenium contamination was primarily responsible for the increased incidence of developmental abnormalities in early life stage fish and birds. Abnormalities included missing or deformed eyes, beaks, wings, legs, and brains. When compared to a control site, selenium concentrations in adult birds at Kesterson were found to be 10 times higher, and selenium concentrations in bird eggs were 20-30 times higher. Overall reductions in body weight were also observed. [16] Concentrations of selenium in bird tissues were found to be positively correlated with the residence time, feeding frequency, and selenium concentration in the birds' diets. [16] Increases in selenium concentration were also observed in plants, fungi, insects, mammals, and fish residing in the reservoir. [17] However, birds are among most sensitive animals to elevated selenium exposure. Due to a steady loss of wetland habitat in California, [16] the Kesterson Reservoir was an important stopping point for migratory birds. For this reason, the high levels of selenium in the reservoir had a substantial effect on bird populations. The findings of the 1983 study were published in newspapers and broadcast on TV, bringing national attention to the issue. This eventually led to the closing of the reservoir in 1986.
After the California State Water Resources Control Board issued a Cleanup and Abatement Order for Kesterson in 1985, the United States Bureau of Reclamation and US Department of the Interior undertook actions to reduce the amount of hazards faced by birds at Kesterson. [1] [2] The United States Bureau of Reclamation and the US Department of Interior undertook remedial actions including filling 713 acres of Kesterson with about 1 million cubic yards of soil [2] and cutting down cattails to eliminate nesting habitats for birds. These actions established 3 primary types of terrestrial habitat including grassland, fill areas dominated by annual plant species, and open areas formerly occupied by cattails. While Se contamination at Kesterson only occurred over a few years, remediation efforts took more than 20 years. [2] Total remediation costs are estimated at $21 million. Additional research conducted at Kesterson determined that microbial volatilization as a bioremediation approach may contribute to considerable removal of selenium from seleniferous soils. [10]
Monitoring began in 1989 and decreased in intensity in 2012. Se monitoring results from 2013 to 2014 indicated that Se concentrations were relatively stable over time such that foraging animals were primarily exposed to concentrations below 4 μg/g. [10] It is recognized that large-scale changes such as flooding may result in rapid mobilization of selenium and greater risk to wildlife. Current alternatives for drainage of contaminated irrigation water are being evaluated, and currently include membrane treatment, selenium removal treatment, and evaporation ponds.
The San Joaquin River is the longest river of Central California. The 366-mile (589 km) long river starts in the high Sierra Nevada, and flows through the rich agricultural region of the northern San Joaquin Valley before reaching Suisun Bay, San Francisco Bay, and the Pacific Ocean. An important source of irrigation water as well as a wildlife corridor, the San Joaquin is among the most heavily dammed and diverted of California's rivers.
The Salton Sea is a shallow, landlocked, highly saline body of water in Riverside and Imperial counties at the southern end of the U.S. state of California. It lies on the San Andreas Fault within the Salton Trough, which stretches to the Gulf of California in Mexico.
The Gunnison River is located in western Colorado, United States and is one of the largest tributaries of the Colorado River.
The Carson River is a northwestern Nevada river that empties into the Carson Sink, an endorheic basin. The main stem of the river is 131 miles (211 km) long although the addition of the East Fork makes the total length 205 miles (330 km), traversing five counties: Alpine County in California and Douglas, Storey, Lyon, and Churchill Counties in Nevada, as well as the Consolidated Municipality of Carson City, Nevada. The river is named for Kit Carson, who guided John C. Frémont's expedition westward up the Carson Valley and across Carson Pass in winter, 1844. The river made the National Priorities List (NPL) on October 30, 1990 as the Carson River Mercury Superfund site (CRMS) due to investigations that showed trace amounts of mercury in the wildlife and watershed sediments.
The Sacramento–San Joaquin River Delta, or California Delta, is an expansive inland river delta and estuary in Northern California. The Delta is formed at the western edge of the Central Valley by the confluence of the Sacramento and San Joaquin rivers and lies just east of where the rivers enter Suisun Bay, which flows into San Francisco Bay, then the Pacific Ocean via San Pablo Bay. The Delta is recognized for protection by the California Bays and Estuaries Policy. Sacramento–San Joaquin Delta was designated a National Heritage Area on March 12, 2019. The city of Stockton is located on the San Joaquin River at the eastern edge of the delta. The total area of the Delta, including both land and water, is about 1,100 square miles (2,800 km2). Its population is around 500,000.
The Kesterson National Wildlife Refuge was an artificial wetland environment, created using agricultural runoff from farmland in California's Central Valley.
Friant Dam is a concrete gravity dam on the San Joaquin River in central California in the United States, on the boundary of Fresno and Madera Counties. It was built between 1937 and 1942 as part of a U.S. Bureau of Reclamation (USBR) water project to provide irrigation water to the southern San Joaquin Valley. The dam impounds Millerton Lake, a 4,900-acre (2,000 ha) reservoir about 15 miles (24 km) north of Fresno.
The Klamath Project is a water-management project developed by the United States Bureau of Reclamation to supply farmers with irrigation water and farmland in the Klamath Basin. The project also supplies water to the Tule Lake National Wildlife Refuge, and the Lower Klamath National Wildlife Refuge. The project was one of the first to be developed by the Reclamation Service, which later became the Bureau of Reclamation.
The Klamath Basin National Wildlife Refuge Complex is a wildlife preserve operated by the United States Fish and Wildlife Service in the Klamath Basin of southern Oregon and northern California near Klamath Falls, Oregon. It consists of Bear Valley, Klamath Marsh and Upper Klamath National Wildlife Refuge (NWR) in southern Oregon and Lower Klamath, Tule Lake, and Clear Lake NWR in northern California.
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