Spring Creek Dam | |
---|---|
Official name | Spring Creek Debris Dam |
Location | Shasta-Trinity National Forest Shasta County, California |
Coordinates | 40°37′47″N122°28′27″W / 40.6298°N 122.4741°W |
Construction began | 1961 |
Opening date | 1963 |
Operator(s) | Bureau of Reclamation |
Dam and spillways | |
Impounds | Spring Creek |
Height | 196 ft (60 m) |
Length | 1,110 ft (340 m) |
Spillway type | Uncontrolled concrete overflow |
Spillway capacity | 5,260 cubic feet per second (149 m3/s) |
Reservoir | |
Creates | Spring Creek Reservoir |
Total capacity | 5,870 acre⋅ft (7,240 dam3) |
Catchment area | 16 sq mi (41 km2) |
Power Station | |
Turbines | 2x 90 MW Francis turbines |
Installed capacity | 150 MW 180 MW (max) |
U.S. Geological Survey Geographic Names Information System: Spring Creek Dam |
Spring Creek Debris Dam is an earthfill dam on Spring Creek, a tributary of the Sacramento River, in Shasta County in the U.S. state of California. Completed in 1963, the dam, maintained by the U.S. Bureau of Reclamation, serves primarily to collect severe acid mine drainage stemming from the Iron Mountain Mine. [1] The dam forms the Spring Creek Reservoir, less than 1 mile (1.6 km) long. Spring Creek and South Fork Spring Creek flow into the reservoir from a 16-square-mile (41 km2) watershed. [2] The dam is directly upstream from the city of Keswick, California and the Keswick Reservoir. [3] The operation is part of the Trinity River Division of the Central Valley Project. [1]
The primary purpose of the Spring Creek Dam was to collect acid mine drainage from the old Iron Mountain Mine, which was heavily polluting Spring Creek and its tributaries. The dam was built in response to these pollutants that were contaminating the Sacramento River, the primary water supply for millions of Californians. Although the watershed is small in comparison to that of the Sacramento River, the stream is among the most polluted and acidic in the world. [4] [5]
The dam and reservoir, along with other treatment structures built at and below the mine, have successfully reduced the dry weather pollution of Spring Creek by up to ninety-five percent. Problems, though, still occur mainly in the form of large uncontrolled spills from the reservoir. Several concerns about the structural integrity and safety of the dam, both physically and biologically, arose in the 1990s. Emergency releases from Shasta Lake, often in the value of thousands of acre feet of water, have occurred from time to time to dilute massive acid spills from the Spring Creek drainage. [5]
The Iron Mountain Mine, the most productive copper mine in California in at least one point along its history, [5] operated along the banks of two Spring Creek tributaries, upstream from the current dam site, from 1879 to the 1960s. The mine extracted iron ore, silver, gold, copper sulfide ore, and pyrite from a rock formation dating to approximately 780,000 years ago. The potential of a mine at the site was discovered in 1860, when two men, surveyor William Magee and settler Charles Camden, discovered an extensive iron ore deposit along one of the tributaries of Spring Creek. In 1879, silver was also discovered at the site, and the mine was begun. The ownership was transferred to Mountain Mines Ltd., a London company, in 1894. At the very end of the 19th century, Iron Mountain Mine took blames for several fish kills in the Sacramento River. Nevertheless, mining activity continued, and by 1928, 600 tons of ore were being extracted from the site per day. [4]
The still continuing problem of Iron Mountain Mine runoff has once been described as:
...[acid mine drainage is] most vividly illustrated by the problems at the Iron Mountain Mine in California.
...release of this waste resulted in virtual elimination of aquatic life in many of the creeks surrounding the Iron Mountain Mine site.
...work is continuing on what is possibly the largest and most difficult acid mine drainage problem in the United States. [6]
-P. Aarne Vesilind. Controlling Environmental Pollution, 2005
The construction of Shasta Dam and its afterbay (regulating downstream dam), Keswick Dam, in 1943 and 1950, respectively, severely impaired the capability of the Sacramento River to flush away pollutants from the mine. Acid mine drainage flowed, unfettered, down Spring Creek directly into the Keswick Reservoir, depositing contaminated sediment and turning a portion of the water a rusty red shade. Previously, the water would have continued down the creek into the river, and flushed to the Pacific Ocean. The pooling of the water, however, made it extremely difficult for the pollutants to be removed. From 1955 to 1962, open pit mining began on the site. At its peak, the mine discharged 5 tons of iron, 650 pounds (290 kg) of copper, and 1,800 pounds (820 kg) of zinc into the stream per day. [5] By then, the water flowing down the drainage was so contaminated that it necessitated the construction of a holding dam, the Spring Creek Dam.
Spring Creek Dam was begun in 1961, when a company named Gibbons and Reed was awarded the contract. The clearing operations began in July of that same year, and the dam was officially dedicated by the Bureau of Reclamation on September 12, 1961. Construction of the dam began on October 20, 1961, with the placing of the dam embankment, which at least partially consists of acidic sediment dredged from Spring Creek. [7] Riprap was laid on the upstream face of the dam beginning November 9 of that year. In 1962, a series of labor strikes impacted communities in the Central Valley, also affecting construction of the dam, which was temporarily halted on May 3 of that year. After work restarted on June 26, pervious core material for the dam was soon out of supply, so impervious material was used to complete the dam core. [8]
Eventually, the Iron Mountain Mine closed, but pollution continued and still continues, and in 1983, the Iron Mountain Mine was listed on the National Priorities List. [4] The Iron Mountain Mine is known for having the most acidic naturally found water content on Earth, with samples having up to a −3.6 pH value when tested in the early 1990s, which is roughly 100 times the acidity of battery acid. [9] [10] However, this pH value is only found inside and near the mine, as the average pH of water entering the Spring Creek Reservoir is 4.12. [11]
The Spring Creek Dam was later deemed "undersized" for the Spring Creek watershed, as the large flows of both natural drainage and acid mine drainage caused frequent uncontrollable spills at the dam. The spills contain many volatile components in acid mine drainage, which include the most acidic naturally occurring (i.e. not in a laboratory) water on Earth. Several alternatives were considered for remediating this problem: [12]
In 1985, it was found that water seepage into the foundations of the Spring Creek Dam could possibly cause its collapse. Shortly after the discovery, a controversy over the irregular spills of mine toxins from the dam began in the 1990s. [8] Two years later, in March 1992, an uncontrolled, unexpected spill of acidic water rushed from the dam down Spring Creek. This spill heavily contaminated the Keswick Reservoir and threatened the water supply of Redding, California. Despite the fact that the region was suffering from a drought, 77,000 acre-feet (95,000 dam3 ) of water were released from Shasta Lake, which was only half full, to dilute the pollution. The loss of the water, which was badly needed by Central Valley agricultural users, was estimated at US$18 million.
A water treatment plant was built on a site named Minnesota Flats near the Iron Mountain Mine, using lime to balance the pH of the acid mine drainage. Water is also diverted from Slickrock Creek to the treatment site. Altogether, over 95 percent of toxins in the water are removed by the treatment process. [5] Roughly 8.5 miles (13.7 km) of specialized acid-resistant pipeline, with a cost of over US$1 million per mile, are included in the treatment process. Most water flowing directly from the mine has a pH level close to 1; the −3.2 pH mentioned earlier is only found in small amounts. Water is further diluted by natural flow in the tributaries and water diverted from nearby Clear Creek, however, the acidic water still requires treatment. [10]
Spring Creek is a southeast-flowing, 9-mile (14 km) long tributary of the Sacramento River, receiving water from approximately 16 square miles (41 km2) of land. [3] The creek begins in the Klamath Mountains above the Sacramento River drainage, and flows in a generally south-east direction before turning south and sharply west into the Spring Creek Reservoir. From the reservoir, it continues due west until it empties directly into an arm of the Keswick Reservoir. The creek never actually runs by the mine. The acid mine drainage found in the creek is actually carried in by two smaller tributaries, which are Boulder Creek and Slickrock Creek. The former stream runs southeast from the north side of Iron Mountain Mine to Spring Creek, while the latter stream drains the south side of the mine and also flows southeast into Spring Creek. South Fork Spring Creek is a small tributary that flows west and north the Spring Creek Reservoir, but since its basin lies far from the mine, it receives no acid mine drainage. [5] The inflow and outflow from the reservoir are highly erratic, ranging from 0 cubic feet (0 m3) per second to roughly 225 cubic feet (6.4 m3) per second in a particular 10-day period from March to April. [13]
Flat Creek, a small southeast-flowing stream, rises in two forks and empties into the Sacramento River upstream of Spring Creek. The stream receives contaminated runoff from the Minnesota Flats Tailing Pile, but is not nearly as polluted or acidic as Spring Creek. Another stream, Rock Creek, rises in three forks and flows east to meet the Sacramento River downstream of Spring Creek and the Keswick Reservoir. [5]
The Spring Creek Dam is 196 feet (60 m) high, 1,110 feet (340 m) long along its crest, and 1,040 feet (320 m) thick at its base. Its crest stands 816 feet (249 m) above sea level. The reservoir is 795 feet (242 m) above sea level at full pool and spillway crest level. When at full pool, the reservoir holds 5,870 acre-feet (7,240 dam3 ) of water with a depth of roughly 184 feet (56 m). One spillway runs over the crest of the dam on the left bank of the canyon. The spillway is 25 feet (7.6 m) wide, able to accommodate a water flow of 5,260 cubic feet (149 m3) per second. The outlet works of the dam are located at the base, and can accommodate a water flow of 660 cubic feet (19 m3) per second. [3] The Spring Creek Powerplant downstream of the dam generates up to 180,000 kilowatts.
The Spring Creek Powerplant is located at the base of the Spring Creek Dam, and is actually supplied by flow from Whiskeytown Lake. The lake, formed by Whiskeytown Dam, is on Clear Creek, a drainage downstream along the Sacramento River from Spring Creek. Both streams run east into the river. The power plant was completed and began operations in 1964, with a capacity of 150,000 kW. The capacity was later upgraded to 180,000 kW. The plant is a peaking power plant with two separate generators, generating power for operations and distributing excess power to the local power grid. Water from Whiskeytown Lake is diverted through the Spring Creek Tunnel, a conduit roughly 2.4 miles (3.9 km) long and 18.5 feet (5.6 m) in diameter. [1]
The Bureau of Reclamation gives a detailed report on the specifications of the generating plant:
The powerplant houses two 13.8kV generators each rated at 100,000 kVA, .90 power factor, along with Francis turbines. Spring Creek Power Conduit conveys water from Whiskeytown Reservoir, located on Clear Creek, to the Spring Creek Powerplant. The Spring Creek power conduit varies in diameter between 5.64 metres (18.5 ft) and 5.18 metres (17.0 ft) and is about 4.8 km (3.0 mi) in length. The power conduit consists of Tunnels No. 1 and No. 2, and Rock Creek Siphon. Twin penstocks take off from Tunnel No. 2 leading to the powerplant. [1]
– U.S. Bureau of Reclamation, Trinity River Division of the Central Valley Project
Spring Creek Reservoir is the artificial lake formed behind the dam. The reservoir is used mostly for flood control storage, and is rarely filled to its 5,870 acre-feet (7,240 dam3 ) capacity. During the dry season, water from Spring Creek pools in a small, stagnant pond retained behind the dam, depositing contaminated sediment and acidic mine waste in the reservoir space. When flows from the Shasta Dam, upstream on the Sacramento River, are sufficient to flush contaminated water away, water held in the reservoir is released through the outlet works into the Keswick Reservoir and the Sacramento River. Despite this operation strategy, the reservoir was eventually deemed inadequate for the watershed, and can be filled to capacity by a single heavy storm event. Uncontrollable spills frequently poured into the Sacramento River during floods, through the crest spillway of the dam, which lacks gates. As a result, numerous fish kills have occurred during these sudden releases of contaminants, a major one of which was in 1969. Due to this consistent acid pollution from the reservoir, most large fish spawn downstream of Red Bluff Diversion Dam, a dam also on the Sacramento River near Red Bluff, California. [14]
The Spring Creek Dam is able to release up to 5,920 cubic feet (168 m3) of water per second from the Spring Creek Reservoir, through a crest spillway and outlet works. The spillway begins on the left bank of the dam at elevation 795 feet (242 m), and drops roughly 184 feet (56 m) in vertical distance down the face of the dam into a stilling basin, before flowing into Spring Creek and into the Sacramento River. It is roughly 25 feet (7.6 m) wide and can carry 5,260 cubic feet (149 m3) per second. The outlet works tunnel through the dam from an elevation much lower than that of the spillway; the conduit terminates at a culvert exit, a design commonly seen on storm drains but rarely seen on dams, at the base of the dam. The maximum capacity of the outlet works is 660 cubic feet (19 m3) per second. [3]
The Sacramento River is the principal river of Northern California in the United States and is the largest river in California. Rising in the Klamath Mountains, the river flows south for 400 miles (640 km) before reaching the Sacramento–San Joaquin River Delta and San Francisco Bay. The river drains about 26,500 square miles (69,000 km2) in 19 California counties, mostly within the fertile agricultural region bounded by the Coast Ranges and Sierra Nevada known as the Sacramento Valley, but also extending as far as the volcanic plateaus of Northeastern California. Historically, its watershed has reached as far north as south-central Oregon where the now, primarily, endorheic (closed) Goose Lake rarely experiences southerly outflow into the Pit River, the most northerly tributary of the Sacramento.
Shasta Dam is a concrete arch-gravity dam across the Sacramento River in Northern California in the United States. At 602 feet (183 m) high, it is the eighth-tallest dam in the United States. Located at the north end of the Sacramento Valley, Shasta Dam creates Shasta Lake for long-term water storage, flood control, hydroelectricity and protection against the intrusion of saline water. The largest reservoir in the state, Shasta Lake can hold about 4,500,000 acre-feet (5,600 GL).
The Pit River is a major river draining from northeastern California into the state's Central Valley. The Pit, the Klamath and the Columbia are the only three rivers in the U.S. that cross the Cascade Range.
The Trinity River is a major river in northwestern California in the United States and is the principal tributary of the Klamath River. The Trinity flows for 165 miles (266 km) through the Klamath Mountains and Coast Ranges, with a watershed area of nearly 3,000 square miles (7,800 km2) in Trinity and Humboldt Counties. Designated a National Wild and Scenic River, along most of its course the Trinity flows swiftly through tight canyons and mountain meadows.
Clear Creek is a tributary of the upper Sacramento River in northern California.
Trinity Dam is an earthfill dam on the Trinity River located about 7 miles (11 km) northeast of Weaverville, California in the United States. The dam was completed in the early 1960s as part of the federal Central Valley Project to provide irrigation water to the arid San Joaquin Valley.
Monticello Dam is a 304-foot (93 m) high concrete arch dam in Napa County, California, United States, constructed between 1953 and 1957. The dam impounded Putah Creek to create Lake Berryessa in the Vaca Mountains.
Navajo Dam is a dam on the San Juan River, a tributary of the Colorado River, in northwestern New Mexico in the United States. The 402-foot (123 m) high earthen dam is situated in the foothills of the San Juan Mountains about 44 miles (71 km) upstream and east of Farmington, New Mexico. It was built by the U.S. Bureau of Reclamation (Reclamation) in the 1960s to provide flood control, irrigation, domestic and industrial water supply, and storage for droughts. A small hydroelectric power plant was added in the 1980s.
Iron Mountain Mine, also known as the Richmond Mine at Iron Mountain, is a mine near Redding in Northern California, US. Geologically classified as a "massive sulfide ore deposit", the site was mined for iron, silver, gold, copper, zinc, quartz, and pyrite intermittently from the 1860s until 1963. The mine is the source of extremely acidic mine drainage which also contains large amounts of zinc, copper, and cadmium. One of America's most toxic waste sites, it has been listed as a federal Superfund site since 1983.
Yellowtail Dam is a dam across the Bighorn River in south central Montana in the United States. The mid-1960s era concrete arch dam serves to regulate the flow of the Bighorn for irrigation purposes and to generate hydroelectric power. The dam and its reservoir, Bighorn Lake, are owned by the U.S. Bureau of Reclamation.
McKay Reservoir is a reservoir in Umatilla County of the U.S. state of Oregon. It is an impoundment of McKay Creek, a tributary of the Umatilla River. The reservoir is located 6 miles (9.7 km) south of Pendleton on U.S. Route 395. The reservoir has a capacity of 65,534 acre-feet (80,835,000 m3) of water. The reservoir and land that immediately surrounds it are designated as the McKay Creek National Wildlife Refuge. The reservoir and creek that it impounds are named for Dr. William C. McKay. McKay was an early settler in the Pendleton, Oregon area. He settled near the mouth of McKay Creek about 1851. The place was originally called Houtama. He died in Pendleton in 1893.
The Spring Creek Reservoir is the artificial lake created by the construction of the Spring Creek Dam across Spring Creek in the Shasta-Trinity National Forest of Shasta County, California, adjacent to Keswick.
O'Neill Dam is an earthfill dam on San Luis Creek, 12 miles (19 km) west of Los Banos, California, United States, on the eastern slopes of the Pacific Coast Ranges of Merced County. Forming the O'Neill Forebay, a forebay to the San Luis Reservoir, it is roughly 2.5 miles (4.0 km) downstream from the San Luis Dam.
Whiskeytown Dam is an earthfill dam on Clear Creek, a tributary of the Sacramento River of northern California in the United States.
Stony Creek is a 73.5-mile (118.3 km)-long tributary of the Sacramento River in Northern California. It drains a watershed of more than 700 square miles (1,800 km2) on the west side of the Sacramento Valley in Glenn, Colusa, Lake and Tehama Counties.
Hayfork Creek is a tributary of the South Fork Trinity River in Northern California in the United States. At over 50 miles (80 km) long, it is the river's longest tributary and is one of the southernmost streams in the Klamath Basin. It winds through a generally steep and narrow course north, then west through the forested Klamath Mountains, but also passes through the Hayfork and Hyampom Valleys, which are the primary agricultural regions of Trinity County.
Keswick Dam is a concrete gravity dam on the Sacramento River about 2 miles (3.2 km) northwest of Redding, California. Part of the U.S. Bureau of Reclamation's Central Valley Project, the dam is 157 feet (48 m) high and impounds the Keswick Reservoir, which has a capacity of 23,800 acre⋅ft (29,400,000 m3). The dam's power plant has three turbines with a generating capacity of 117 megawatts (MW), which, in 1992, was uprated from its original 75 MW. The dam and reservoir serve as an afterbay to regulate peaking power releases from the Shasta Dam upstream.
Gibraltar Dam is located on the Santa Ynez River, in southeastern Santa Barbara County, California, in the United States. Forming Gibraltar Reservoir, the dam is owned by the city of Santa Barbara. Originally constructed in 1920 and expanded in 1948, the dam and reservoir are located in a remote part of the Los Padres National Forest.
Cottonwood Creek is a major stream and tributary of the Sacramento River in Northern California. About 68 miles (109 km) long measured to its uppermost tributaries, the creek drains a large rural area bounded by the crest of the Coast Ranges, traversing the northwestern Sacramento Valley before emptying into the Sacramento River near the town of Cottonwood. It defines the boundary of Shasta and Tehama counties for its entire length. Because Cottonwood Creek is the largest undammed tributary of the Sacramento River, it is known for its Chinook salmon and steelhead runs.
Red Bluff Diversion Dam is a disused irrigation diversion dam on the Sacramento River in Tehama County, California, United States, southeast of the city of Red Bluff. Until 2013, the dam provided irrigation water for two canals that serve 150,000 acres (61,000 ha) of farmland on the west side of the Sacramento Valley. The dam and canals are part of the Sacramento Canals Unit of the Central Valley Project, operated by the U.S. Bureau of Reclamation. In 2013, the dam was decommissioned and the river allowed to flow freely through the site in order to protect migrating fish. A pumping plant constructed a short distance upstream now supplies water to the canal system.