D--048966 - CALFED Bay-Delta Program - State of California

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VOLUME II, CHAPTER 30
(Slotten et al. 1995). The heavy metal is readily trapped in River Basin near Monitor Pass was started by the Anaconda
reservoir sediments, and lower concentrations have been Copper Company in 1953. Overburden was dumped in the
measured below reservoirs than above (Slotten et al. 1995). stream channel, causing the water to percolate through the
Mercury concentrations exceeded 0.5 rag/kg in sediment material. Below the stream blockage, the water is highly acidic
samples obtained from Camp Far West Reservoir, Lake Wild- and polluted with toxic materials. The stream was sterile bewood,
Lake Amador, and Moccasin Reservoir (Central Val- low the mine during the 1950s. In 1969, an isolated populaley
Regional Water Quality Control Board 1987). Certain tion of rainbow trout still existed in the unpolluted portion of
bacteria can convert metallic mercury to a methylated form Leviathan Creek above the mine. Below the mine, fish and
that can be incorporated in tissue. Mercury tends to accumu- macroinvertebrates were absent from 18 km (11 mi) of stream
late in the food chain. Although the opportunity for bacterial affected by the mine drainage. The effects of the pollution
mercury methylation is minimized in cold, swift streams, the even extend for 3 km (2 mi) in the East Fork of the Carson
process can occur in the calm waters of reservoirs (Slotten et River below the confluence with the contaminated creek
al. 1995). However, the reservoirs do not appear to be net ex- (Davis 1969; Hammermeister and Walmsley 1985). Attempts
porters of bioavailable mercury. Instead, they seem to be sinks at revegetating the spoils began in the 1970s (Everett et al.
for both bioavailable and inorganic mercury (Slotten et al.
1995). Tissue samples of fish caught in the Yuba River con-
1980).
tained more than 1 mg/kg, and samples exceeding 0.5 mg/
kg were found in fish caught in Pardee, Don Pedro, and
Reclamation
McClure Reservoirs (Central Valley Regional Water Quality California’s Surface Mining and Reclamation Act of 1975 and
Control Board 1987). A National Academy of Sciences report amendments should prevent future disasters (Pomby 1987),
suggests that mercury amounts in tissue exceeding 0.5 mg/ but remediation of past problems requires massive investkg
may be injurious to animals, ments. Even ascertaining the location of abandoned mines
The Penn mine near the lower Mokelumne River has been remains problematic (Desmarais 1977). Sealing of much of the
considered one of the worst abandoned-mine problems in the Walker mine, a notorious problem in Plumas County, in 1987
Sierra Nevada. The mine was opened in 1861 and operated significantly lowered copper concentrations in receiving wacontinuously
until 1919 and then sporadically until the 1950s. ters and allowed partial recolonization of formerly sterile
Copper and zinc were the primary products of the mine (Heyl reaches by macroinvertebrates (Bastin et al. 1992). There is
et al. 1948). More than 16,000 m (55,000 ft) of tunnels and the also a major question of liability in cleanup efforts. Current
associated spoil provide the opportunity for percolating law holds those attempting remediation to be liable for any
ground water to become acidic and leach zinc, copper, and damage caused by their activities or, presumably, failure of
cadmium from the mine. Flushing of some of the mine shafts the project to solve the problem. Therefore, under the cloud
in 1937 killed fish for 100 km (60 mi) downstream. A series of of legal liability, little action is undertaken by private or pubretention
ponds were constructed and other attempts were lic agencies (California State Lands Commission 1993). Scores
made to restrict movement of the contaminants into the river of small mines have been established under the terms of the
in the 1980s, but they have had limited effectiveness (Califor- antiquated 1872 Mining Act. In many cases, the properties
nia State Lands Commission 1993). Until 1929, water drain- are sources of sediment and toxic chemicals. Reform of poring
from the mine into the Mokelumne River was diluted by tions of the Mining Act could finally alleviate some major land
the large volume of discharge. However, after the construc- and water management problems associated with mining.
tion of Pardee Dam by the East Bay Municipal Utility District Conversely, legislation has been introduced in California to
and export of up to one-third of the annual volume of the weaken the state’s regulations regarding reclamation of mined
river upstream of the mine, concentrations of contaminants
in the Mokelumne increased (Slotten et al. 1994). The dam for
land.
Camanche Reservoir just downstream of the mine was cornpleted
in 1964. Toxic materials leached from the mine are
Future Prospects
stored in sediments trapped by the dam. The potential for Changes in mineral economics and technology and new disresuspension
of the metals is minimal as long as water levels coveries may lead to new mines. Reactivation of a large unare
kept relatively high (Slotten et al. 1994). In December 1993, derground gold mine near Grass Valley has been proposed.
the Environmental Protection Agency ordered the East Bay Water pumped out of that mine would probably require thor-
Municipal Utility District to control pollution from the mine. ough treatment before it could be discharged. In the eastern
However, the utility contends that it is not responsible for the ¯ Sierra Nevada, the tungsten mine in Mt. Morgan on Pine Creek
mine, which was last operated by the federal government has been maintained on a standby basis awaiting an increase
during the Korean Wan in the price of the metal. Reactivation of gold mines at Bodie
The Leviathan mine provides another example of a water and Independence Creek have been explored in recent years.
quality problem resulting from an abandoned operation. A A disseminated gold deposit in Long Valley near Mammoth
copper and sulfur mine on Leviathan Creek in the Carson Lakes has been identified through exploratory drilling in
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