Английская Википедия:East Fork Russian River
Шаблон:Infobox river East Fork Russian River is a Шаблон:Cvt long tributary of the Russian River in Mendocino County, California artificially connected to the Eel River via an interbasin diversion at the Potter Valley Project hydroelectric facility. It forms in the north of Potter Valley, flows south through this valley, then southwest through a mountain pass to Lake Mendocino, an artificial reservoir that empties into Russian River. At one time Clear Lake to the east drained through Cold Creek then along the lower part of East Fork Russian River through Coyote Valley to the Russian River proper. A few hundred years ago a massive landslide blocked this channel, and Clear Lake found a new outlet to the Sacramento River.
Cold Creek flows year round, while the upper part of East Fork Russian River used to dry up in the summer leaving isolated pools along its course. This changed when the Potter Valley Project was completed in 1908. The project involved construction of two reservoirs on Eel River to the north of the Russian River basin, and a tunnel to the head of Potter Valley that carried water from Eel River to a hydroelectric station that discharged into East Fork Russian River. The Eel River water was used to irrigate Potter Valley, and supplied water to Ukiah below the convergence with Russian River. In 1958 Coyote Dam was built on East Fork Russian River just above its mouth on Russian River, flooding Coyote Valley to form Lake Mendocino. The lake provides additional water storage as well as flood control.
The continuous flow from the Potter Valley Project changed the fish ecosystem in the Russian River by eliminating the warm, still pools that had been used for breeding by native fish. In the 1950s the state introduced poison to the river to eliminate "useless" fish species in favor of game species. The Coyote Dam prevented steelhead trout from returning upstream, so today the East Fork Russian River is dominated by rainbow trout. The section of the river that flows through the mountains between Potter Valley and Lake Mendocino includes stretches of white water that are challenging for kayakers and rafters.
Watershed
The East Fork Russian River is a Шаблон:Cvt long tributary of the Russian River in Mendocino County.Шаблон:Sfn It drains the northeastern part of the Russian River basin.Шаблон:Sfn The region has a Mediterranean climate.Шаблон:Sfn The fork's watershed covers Шаблон:Cvt.Шаблон:Sfn The mouth elevation is about Шаблон:Cvt above sea level.Шаблон:Sfn East Fork Russian River forms in the north end of Potter Valley and flows south through a canyon to Coyote Valley, now filled by Lake Mendocino.Шаблон:Sfn
Potter Valley is an alluvial valley, a depression created by movement of parallel faults that has filled with gravel, boulders and cobble eroded from the surrounding mountains.Шаблон:Sfn The basement rock is Franciscan Complex, a jumbled mixture of different types of rock that is very prone to erosion and landslides.Шаблон:Sfn Coyote Valley is a southerly trending valley about Шаблон:Cvt wide by Шаблон:Cvt long that is underlain primarily by metamorphic rocks from the Franciscan formation. Most of the recreation areas located within the Lake Mendocino boundary have 6 to 12 inches of silt, or sandy silt, overlying the gravelly phase, Older Alluvium.Шаблон:Sfn
Coyote Valley is flanked by rolling hills that rise Шаблон:Cvt about the valley floor to the west of Lake Mendocino and steeper Franciscan bedrock hills to the east.Шаблон:Sfn Elevations above mean sea level in the surrounding region range from about Шаблон:Cvt in the valleys near Ukiah to about Шаблон:Cvt on top of Cow Mountain to the east.Шаблон:Sfn The hills to the east of Lake Mendocino are very rugged and continue for many miles. To the west and northwest, the hills are more rounded with benches that were once planted with vineyards.Шаблон:Sfn
In a period of very low water in September 1905 the East Fork Russian River had a discharge of Шаблон:Cvt.Шаблон:Sfn A discharge measurement station is located Шаблон:Cvt upstream from the Russian River and Шаблон:Cvt downstream from the Coyote Dam, which impounds Lake Mendocino. At this point the maximum discharge of the East Fork Russian River before regulation by Lake Mendocino was Шаблон:Cvt, recorded on 21 December 1955. Since then the maximum discharge was Шаблон:Cvt, recorded on 24 January 1970.Шаблон:Sfn
Course
Tributaries in the Potter Valley include Adobe Creek, Burright Creek and Mewhinney Creek from the left and Busch Creek, Williams Creek, Bevans Creek and White Creek from the right.Шаблон:Sfn Today the river's primary source of water is the Powerhouse Canal from the Potter Valley Project.Шаблон:Sfn The project began to transfer water from the Eel River into the East Fork Russian River in 1908 to generate electricity and support irrigation. The water has been used in the Potter Valley for alfafa, grapes and rice.Шаблон:Sfn The river flows south through the valley, then runs southwest through mountainous territory to Lake Mendocino, formed by the Coyote Dam near the point where East Fork enters the main Russian River.Шаблон:Sfn
In the canyon between Potter Valley and Lake Mendocino, the East Fork receives the left tributary Cold Creek, which flows from Lake County to the east. A 1914 survey of the Ukiah Area said the Cold Creek Valley was small and not very important agriculturally. It was interesting because it belonged to a middle-aged stream that was now tributary to a very youthful stream. The East Fork of the Russian River has a youthful topography in this section, flowing with a high gradient through a V-shaped gorge. Cold Creek flows at a much lower gradient, as is shown by the size of stones in its bed, and has a distinct flood plain and also a terrace.Шаблон:Sfn
California State Route 20 runs east from Route 101 to the north of Ukiah. It skirts the north shore of Lake Mendocino and then crosses East Fork Russian River near the northeast corner of the lake. It follows the river for about two miles, then turns to the southeast along Cold Creek. Potter Valley Road continues from Highway 20 along East Fork Russian River, which it crosses twice before reaching Potter Valley.Шаблон:Sfn McKee Park is in the south of Potter Valley beside the Potter Valley Road and stretches along the East Fork Russian River for about Шаблон:Cvt. This section of the river is shaded by various types of native oaks and bay trees. The waters may be dangerous, and there are no attendants, but visitors may wade, swim or fish along the river.Шаблон:Sfn
Geological changes
Clear Lake, to the east of the Russian River, formed about 600,000 years ago as the land in the region began to subside when the Clear Lake Volcanic Field erupted.Шаблон:Sfn The Clear Lake basin lies between the watersheds of the Sacramento River and the Russian River. When it was formed it drained east into the Sacramento Valley.Шаблон:Sfn About 200,000 years ago the Clear Lake Volcanic Field blocked the lake's outlet.Шаблон:Sfn The lake rose until it found a new outlet, draining west through the Blue Lakes into Cold Creek and the Russian River.Шаблон:Sfn This could account for the relatively mature profile of Cold Creek.Шаблон:Sfn At some time in the last 10,000 years a landslide at the west end of the Blue Lakes blocked Clear Lake's outlet to the Russian River watershed. The lake rose again, and created its present outlet via Cache Creek to the Sacramento River.Шаблон:Sfn
At one time the lower part of what is now East Fork Russian River from the present mouth of Cold Creek down through Coyote Valley to Russian River proper was also called Cold Creek. In 1908 the Potter Valley Project transferred water from the Eel River to the powerhouse in Potter Valley, and its discharge flowed out through the East Fork Russian River, to which Cold Creek is a tributary.Шаблон:Sfn Before the Eel River water was diverted, the East Fork would nearly dry up in July, August and September. A flour mill in Coyote Valley had water to drive its wheel carried from Cold Creek, which runs year round, along Шаблон:Cvt of flume.Шаблон:Sfn
Potter Valley Project
The upper Eel River runs to the north of the ridge at the north end of Potter Valley, and in this section is Шаблон:Cvt higher than the headwaters of East Fork Russian River. The Potter Valley Project was begun in 1900 to exploit the hydroelectric potential. The concrete gravity and earth filled Cape Horn Dam was built to impound a reservoir called Lake Van Arsdale on the Eel River. A tunnel Шаблон:Cvt in diameter lined with redwood timbers was excavated for more than Шаблон:Cvt south to emerge above the northern end of Potter Valley. The water then fell through a penstock with vertical elevation of more than Шаблон:Cvt to the Potter Valley Powerhouse, which came online in April 1908 to deliver 4 MW. It was upgraded to 7 MW in 1910, a second penstock was built in 1912, and in 1917 the powerhouse was upgraded to 9.4 MW.Шаблон:Sfn
At first the powerhouse only ran at full capacity in the winter, and had to shut down completely in summer due to lack of water. In 1920 work started on Scott Dam, a large concrete ogee gravity structure Шаблон:Cvt upstream from Van Arsdale which collects water from the upper 7.3% of the Eel River watershed. It was completed in 1922 and began to fill Lake Pillsbury, which has a storage capacity of Шаблон:Cvt and releases water for the powerhouse throughout the year. The Pacific Gas and Electric Company (PG&E) acquired the project in 1930.Шаблон:Sfn
The Potter Valley Project maintains minimum instream flow in the East Fork Russian River and in the Eel River. Some of the water from the generating station is used by the Potter Valley Irrigation District, while the remainder flows to Lake Mendocino.Шаблон:Sfn In 1969 water diversion from the Eel River into the Russian River basin ranged from Шаблон:Cvt.Шаблон:Sfn Spent water from the power station averaged Шаблон:Cvt and allowed for more croplands in the Potter and Ukiah valleys to be irrigated, as well as allowing more urban and industrial development along the river.Шаблон:Sfn The power meets the needs of the city of Ukiah, and the water is valuable for agriculture, fish and recreation.Шаблон:Sfn
Lake Mendocino
The East Fork Russian River is impounded near its mouth to form Lake Mendocino by the Coyote Dam, a rolled earth embankment built by the United States Army Corps of Engineers (USACE). The reservoir's catchment area is about Шаблон:Cvt and holds a water supply pool of Шаблон:Cvt.Шаблон:Sfn The embankment is Шаблон:Cvt high and has a crest length of Шаблон:Cvt.Шаблон:Sfn Construction of the Coyote Dam began in July 1956. The USACE proposed to only clear a strip of land around the reservoir from the Шаблон:Cvt elevations. Residents were concerned that underwater trees, stumps and debris would be dangerous to swimmers, boaters and fisherment, and in the summer of 1958 volunteers cleared most of the basin, cutting down and burning the trees.Шаблон:Sfn Highway 20, which had crossed Coyote Valley, was rerouted around the new reservoir.Шаблон:Sfn
The dam began to store water in 1959. It serves the dual purpose of protecting against floods and supplying water.Шаблон:Sfn The USACE is responsible for flood control and Sonoma Water controls water release. Operations are not coordinated with the Potter Valley Project.Шаблон:Sfn A 3.5 MW hydroelectric power plant operated by the City of Ukiah came into operation in 1986.Шаблон:Sfn Lake Mendocino is used for recreational purposes such as camping, swimming, hiking, fishing, and boating.Шаблон:Sfn All the facilities are operated by the USACE.Шаблон:Sfn
A large amount of fine sediment is transported through the water diversion on Eel River, causing turbidity in Lake Mendocino during the first heavy runoff of the year and for several months afterwards.Шаблон:Sfn Normally sediment migrates steadily down the river. The Coyote Dam impounds bedload, and the sediment-poor water it releases erodes the bed and banks of the river downstream in the Ukiah Valley.Шаблон:Sfn After a major storm, flood releases from the Coyote Dam may also cause erosion of the river banks.Шаблон:Sfn In February 2019 torrential rains caused serious floods on the lower Russian River. In June 2021 the river's tributaries were almost dry due to a severe drought. Lake Mendocino and Lake Sonoma, further downstream, were only releasing the minimum amount of water needed for fish and wildlife to survive. Relief was not expected until the winter rains, and meanwhile fish were struggling to survive in river pools.Шаблон:Sfn
Fish
The alternation of the Clear Lake drainage route in the past explains why there are many fish species common to the Russian River and the Sacramento River.Шаблон:Sfn Native fish species that currently inhabit, or that have historically inhabited the East Fork of the Russian River, include steelhead trout (Oncorhynchus mykiss), chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), rainbow trout (oncorhynchus mykiss irideus), hardhead (Mylopharodon conocephalus), Pacific lamprey (Entosphenus tridentata), Sacramento pikeminnow (Ptychocheilus grandis), Sacramento sucker (Catostomas occidentalis occidentalis) and Russian River tule perch (Hysterocarpus traskii pomo).Шаблон:Sfn
Numerous non-native species also inhabit the East Fork including bluegill (Lepomis macrochirus), brown bullhead (Ameiurus nebulosis), common carp (Cyprinus carpio), golden shiner (Notemigonus crysoleucas), green sunfish (Lepomis cyanellus), largemouth bass (Micropterus salmoides), redear sunfish (Lepomis microlophus), smallmouth bass (Micropterus dolomieu) and western mosquitofish (Gambusia affinis).Шаблон:Sfn
Before 1908 the Russian River was reduced in the summer to a series of deep pools that hosted many small fish. The constant flow of cooler water changed the summer conditions in East Fork Russian River and downstream in Russian River, degrading the spawning habitat.Шаблон:Sfn In 1954 the Department of Fish and Game began a program to eradicate "trash" fish in the Russian River below East Fork. The rotenone poison was sprayed into the river, which had the effect of suffocating resident fish such as squawfish, suckers, roach, carp, hardhead minnows, green sunfish and lampreys, as well as smallmouth bass, and steelhead trout. Some migratory game fish were also killed.Шаблон:Sfn Since 1959 the Coyote Dam has blocked steelhead trout from returning to the river, so the valley's streams are dominated by rainbow trout.Шаблон:Sfn The state regularly restocks the East Fork with rainbow trout.Шаблон:Sfn
Common species in Lake Mendocino now include largemouth bass, smallmouth bass, striped bass (Morone saxatilis), bluegill, black crappie (Pomoxis nigromaculatus), white crappie (Pomoxis annularis), channel catfish (Ictalurus punctatus), white bullhead (Ictalurus catus), brown bullhead (Ameiurus nebulosis) and a variety of non-game species. Rainbow trout stocked in the river above the lake occasionally migrate downstream for brief periods in the spring and fall, when dissolved oxygen levels in the lake are higher.Шаблон:Sfn
Kayaking
A Шаблон:Cvt stretch of the river between Three Rocks Falls below Potter Valley down to Lake Mendocino is a class II+ run for kayakers. Its gradient is about Шаблон:Cvt and flow is about Шаблон:Cvt. Flow is good all year round due to controlled release from the upstream reservoirs, but best in the autumn. The Three Rock Falls itself is a class V–VI rapid where several inner tubers have died, and should be avoided by most kayakers in most water conditions.Шаблон:Sfn
Notes
Sources
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