Mono Basin Creeks: Rush, Parker, Walker, Lee Vining, Mill
Click on footnotes -- 1 -- to see the notes at the bottom of the profiles. Click on words in italics to see the definition in the glossary.
Beginning in 1941, four of the five major streams in the Mono Basin -- Rush, Lee Vining, Parker, and Walker Creeks -- were diverted by the Los Angeles Department of Water and Power (DWP) into the Los Angeles Aqueduct to increase L.A.'s water supply. Mill Creek was never diverted to Los Angeles. Below the diversion points, the creek ecosystems were destroyed by the lack of water, occasional floods, and the dropping level of Mono Lake.
Most of the streams that were not diverted into the Los Angeles Aqueduct are similar in condition to the way they were in 1940, except for their mouths which have been affected by the dropping level of Mono Lake. Before 1941, the streams in the Mono Basin were lined with almost continuous corridors of woodland habitat from montane conifer forests to within a quarter mile of the lakeshore. These wildlife corridors provided important resting, foraging, and nesting habitat.1
South and East Parker Creeks contribute 1,200 acre-feet of runoff from their 3.8 square mile watershed which begins at 12,600-foot Mt. Wood. DeChambeau Creek's 2.5 square mile watershed contributes 900 acre-feet, most of which is diverted for irrigation. Average net inflow to Mono Lake from ungauged sources is estimated to be 35,000 acre-feet per year.2 These sources include springflow and intermittent streams from the Bodie Hills. Also included in this figure are Horse Creek, most of which is diverted for irrigation, Bohler Creek, which is diverted for pasture irrigation at the north end of Cain Ranch, and Post Office Creek.
Rush Creek is the largest stream in the Mono Basin, carrying 41% of the total runoff.3 Its 141 square mile watershed begins in the Ansel Adams Wilderness at Mt. Lyell, over 13,000 feet in elevation,4 and provides an average of 59,200 acre-feet of runoff each year to the stream.5 The watershed also includes Reversed Creek, which begins near June and Gull Lakes and enters Rush Creek just above Silver Lake. Southern California Edison's Rush Creek Power Plant, on Rush Creek just upstream from this confluence, is at the foot of the sometimes-spectacular falls to the north of Carson Peak. Alger Creek adds its flow to Rush Creek between Silver Lake and Grant Lake.
Before 1916-1925, when three dams were constructed to enlarge natural lakes and flood meadows in the 23.2 square mile upper watershed6 for hydropower, peak flows would reach up to 1,100 cubic feet per second (cfs) at the height of snowmelt.7 The ability for Waugh Lake to store up to 4,980 acre-feet of runoff, Gem Lake to store up to 17,060 acre-feet, and Agnew Lake to store up to 860 acre-feet8 has cut in half the maximum peak flow released below Agnew Lake,9 and on average reduced it to about 175 cfs.10
Between the 1860s and the late 1930s water was diverted from Rush Creek for irrigated agriculture, and in the 1920s major irrigation diversions began after Grant Lake was enlarged by an artificial dam.11 These diversions irrigated 1000 acres in Pumice Valley with enough water to enhance springflow in the Rush Creek Bottomlands.12
After Rush Creek passes through Grant Lake, Parker and Walker Creeks enter it just above the Narrows. The Narrows is a point where steep cliffs rise up from both sides of the stream, and the Rush Creek Bottomlands extend from the Narrows to Mono Lake. Before 1941, dense riparian vegetation in the Bottomlands supported abundant waterfowl and other wildlife such as mallards, teals, ducks, geese, deer, mountain lions, bobcats, and coyotes, while at the mouth of Rush Creek there were large riparian trees, especially cottonwoods, and rabbits, deer, and large flocks of ducks and geese.13 The Bottomlands contained a broad riparian forest, a sinuous main channel and in some places multiple channels, excellent quality spawning gravels, exposed willow roots, some fallen trees, and shoreline debris jams, which provided wildlife habitat and especially fish habitat.
There are no fish native to the Mono Basin, but shortly after 1850 Lahontan Cutthroat Trout were introduced to the streams, and an abundant fishery flourished by 1900. Above Grant Lake Golden Trout were planted in the 1920s and 1930s, and at some point threespine stickleback were introduced into the system along with steelhead trout from the Ventura River.14
An egg collecting station was constructed on Lower Rush Creek in 1925 and operated through 1953, during which time most eggs were probably shipped to the Mt. Whitney Hatchery. The Fern Creek Hatchery between Silver Lake and Grant Lake produced approximately 1 million fish per year from 1928 to 1942.15
Brown, Rainbow, and Brook Trout were stocked from Fern Creek and Mt. Whitney State Fish Hatcheries in the Early 1900s. Brown Trout were introduced in 1919, were well established by 1931, dominated the fishery by 1940, and were stocked until 1942. 3/4lb. to 2 lb. brown trout were common, and occasionally a 5-6 lb. fish was caught. During the Great Depression trout from Rush Creek regularly supplanted the diets of local residents.16
Los Angeles Aqueduct Diversion Impacts:
Grant Lake was previously enlarged by an irrigation dam, and by 1941 the current dam enlarged it enough to hold 47,575 acre-feet of water.17 Diversions of water from Grant Lake into the Los Angeles aqueduct began in 1941.
Because of high runoff, little changed below Grant Lake Dam until 1947. From 1948-1951 there was low runoff, and below Hwy 395 many pines died. There were highly variable releases during the 1950s, and during this time cottonwoods and willows declined above the narrows. Consistently low releases during the early 1960s caused a rapid loss of riparian vegetation, while some vegetation managed to survive on springflow in parts of the bottomlands. With most riparian vegetation dead and dying, extreme floods in 1967 and 1969 were able to severely scour the channels and remove large amounts of live and dead vegetation and topsoil. By this time, Mono Lake had dropped 28 feet, and Rush Creek had incised into its floodplain in order to reach this lower lake level. The water table dropped along with the elevation of the stream, and this along with little or no releases of water during the 1970s caused most remaining vegetation to die or become severely degraded. High runoff in 1980, 1982, and 1984 caused even more damage, and increased incision and widening drained groundwater from adjacent riparian habitats.18
These high flows brought trout down the creeks, however, and California Trout, Inc., the National Audubon Society, and the Mono Lake Committee sued LADWP for continuous low flows in Rush Creek to maintain trout populations in good condition, which was ordered by the court in 1985. These low flows and a 1991 grazing moratorium also allowed modest recovery of riparian vegetation to occur.19
As of 1989, there were 135 acres of mature woody vegetation, 33 acres of newly establishing riparian vegetation, and 40 acres of meadows. This is a 50% loss of pre-diversion woody riparian vegetation, and a 70% loss of pre-diversion meadowlands. Near its mouth, Rush Creek incised 30 feet below its former floodplain, and the new floodplain is considerably narrower.20 Most of the distributary channels parallel to the main channel are dry and blocked with debris. Instream fish habitat is considerably poorer, due to a lack of pools, spawning gravels, and woody debris. There are now 48 species of birds, mammals, and reptiles that use Rush Creek habitats.21
In order to restore Rush Creek's previous rich habitats, various stream restoration techniques are being implemented. These include rewatering dry distributary channels, managing flows from Grant Lake to mimic natural flows, and planting vegetation in certain areas. These activities, if effective, should restore the stream to a dynamic and functioning ecosystem resembling pre-1941 conditions.
Parker Creek carries 6% of the total Mono Basin Runoff.22 Its 12.2 square mile watershed begins in the Ansel Adams Wilderness at 13,000 foot Kuna Peak.23 An average of 9,100 acre-feet of runoff each year flows down the stream,24 and during peak snowmelt, average peak flows in Parker Creek can reach 90 cfs.25 Several branches drain steep, mountainous terrain with permanent snowfields on the north sides of peaks. Parker Creek flows through Parker Lake, a natural alpine lake at 8,300 feet above sea level, and then through a narrow moraine-bound canyon broadening in alluvial deposits and Cain Ranch pasturelands. Here 1,500 acre-feet of water each year is diverted to Cain Ranch for irrigation. From there Parker Creek enters Rush Creek, which carries its waters to Mono Lake.26
Before 1941, Parker Creek below Parker Lake was lined with meadows, watercress, and dense riparian vegetation near its confluence with Rush Creek.27 A group of 30-50 sage grouse used the Parker Creek Meadow as a lekking site.28 In the late 1800s and early 1900s, several species of trout were introduced, and anglers could catch a limit of 8-10 inch Eastern Brook Trout in 2-3 hours.29 It also was an important nursery and breeding area for trout in Rush Creek.30
Los Angeles Aqueduct Diversion Impacts:
The Lee Vining Conduit crosses Parker Creek above the irrigated pasturelands of Cain Ranch, and since 1947 diverted virtually all of the water in Parker Creek into the Los Angeles Aqueduct via Grant Lake. This dried up the stream below the conduit, causing a loss of riparian vegetation and aquatic habitat. Gravel was pushed into the dry channel by CalTrans, forming a feature known as "Parker Plug," which was removed in 1990, marking the beginning of stream restoration on Parker Creek.31
As of 1989, there were 49 acres of woody riparian vegetation along Parker Creek, mostly highly stressed willow scrub; 9 acres less than pre-1941 conditions. There were also extensive rush-dominated meadows, and a total of 32 different species of birds, mammals, and reptiles.32 The number of sage grouse has declined to an unknown but still present number.33
In 1990, water flowed down Parker Creek again as a result of a court order.34 Minimum flows were set by the State Water Resources Control Board (SWRCB) in 1994, and stream restoration, which started in 1990, is continuing to restore the stream to a healthy, dynamic ecosystem.
Walker Creek carries 4% of the total Mono Basin Runoff.35 Its 7.8 square mile watershed begins in the Ansel Adams Wilderness at 12,800 foot Mt. Gibbs.36 An average of 5,400 acre-feet of runoff each year flows down the stream,37 and during peak snowmelt, average peak flows in Walker Creek can reach 70 cfs.38 Steep, mountainous terrain mostly above treeline drains from Mono Pass through Bloody Canyon to Walker Lake, a natural lake enlarged for irrigation and recreational use, with a usable storage of 550 acre-feet. It then flows through a narrow moraine-bound canyon broadening in alluvial deposits and Cain Ranch irrigated pasturelands. Here 2,400 acre-feet of water each year was diverted to 2,000 acres of Cain Ranch for irrigation. From there Walker Creek descends through a narrow canyon eroded into former lakebeds to Rush Creek, which carries its waters to Mono Lake.39
Walker Creek below Walker Lake is lined with meadows, watercress, and near the confluence with Rush Creek dense riparian vegetation. In the late 1800s and early 1900s, several species of trout were introduced, and anglers could catch a limit of 8-10 inch Eastern Brook Trout in 2-3 hours.40 It also was an important nursery and breeding area for trout from Rush Creek.41
Los Angeles Aqueduct Diversion Impacts:
The Lee Vining Conduit crosses Walker Creek above the irrigated pasturelands of Cain Ranch, and since 1947 diverted virtually all of the water in Walker Creek into the Los Angeles Aqueduct via Grant Lake. This dried up the stream below the conduit, causing a loss of riparian vegetation and aquatic habitat.
As of 1989, there were 43 acres of woody riparian vegetation along Walker Creek, mostly highly stressed willow scrub; 7 acres less than pre-1941 conditions. There were also extensive rush-dominated meadows,42 and a total of 29 different species of birds, mammals, and reptiles.43
In 1990, water flowed down Walker Creek again as a result of a court order.44 Minimum flows were set by the State Water Resources Control Board (SWRCB) in 1994, and stream restoration, which started in 1990, is continuing to restore the stream to a healthy, functioning ecosystem.
LEE VINING CREEK
Lee Vining Creek is the second largest stream in the Mono Basin, carrying 33% of the total runoff.45 Its 47 square mile watershed begins in the Ansel Adams Wilderness at 13,053 foot Mt. Dana,46 and provides an average of 48,500 acre-feet of runoff each year to the stream.47 The watershed also includes several small glaciers, the Warren Fork of Lee Vining Creek, and Gibbs Creek, which has half of its flow diverted for irrigation.48 Southern California Edison's Poole Power Plant has been operating since 1923, and is on Lee Vining Creek just below Lee Vining Creek Falls.49
Before dams were constructed to enlarge three natural lakes for hydropower, peak flows would reach up to 650 cfs at the height of snowmelt.50 The ability for Saddlebag Lake to store up to 11,080 acre-feet of runoff, Tioga Lake to store up to 1,250 acre-feet, and Ellery Lake to store up to 490 acre-feet51 has cut the maximum peak flow released below Ellery Lake to 475 cfs.52
Downstream from these alpine lakes, beginning after 1860, settlers diverted water for sawmills; and irrigation and hydropower diversions increased through the late 1800s and early 1900s. Forests along Lee Vining Creek supported a tremendous diversity of birds.53 Where Lee Vining Creek reached the mouth of the glacial canyon, its floodplain broadened over alluvial deposits, allowing a multiple channel system to exist. One main channel with several subsidiary channels provided a diversity of aquatic habitats able to support all trout life stages. The channels were narrow with frequent meanders, providing deep water habitat, undercut root wads, lateral scour pools, and abundant trout spawning gravels. Dense riparian cover along most of the creek provided cover, shade, stabilization of streambanks, rootwads, and fallen trees. High summer flows and cooler water temperatures maintained productive aquatic habitat all the way to the delta in Mono Lake.54
Shortly after 1850, Lahontan Cutthroat Trout were introduced into the fishless stream, and an abundant fishery existed by 1900. Brown trout and Rainbow trout were planted from the early 1900s until 1941, and by 1940 Brown trout were the most abundant species of fish. 8-10 inch trout were abundant, with some fish reaching 13-15 inches.55
Los Angeles Aqueduct Diversion Impacts:
In 1941 diversion of water from Lee Vining Creek into the Los Angeles Aqueduct began. The Lee Vining Conduit diverts water from the stream at the diversion dam just upstream from the Lee Vining Ranger Station. After 1947, high runoff ceased and pasture irrigation ended, causing the stream to be virtually dry below the diversion dam. The canyon is narrow below the diversion dam to a point a half mile below Highway 395, and this kept soils moist enough for vegetation to survive. Below this point, vegetation declined rapidly, and was severely affected all the way to Mono Lake. In 1954 a fire consumed much of this dead and some live riparian vegetation. The stream was nearly or completely dewatered until a 1969 flood caused severe channel widening, migration, and incision.
In 1986, continuous low flows were obtained with a court order, and modest recovery of riparian vegetation occurred in places. A grazing moratorium was instituted in 1991, allowing further recovery of vegetation. As of 1989, there were 60 acres of mature woody riparian vegetation (44 acres upstream of .5 miles below Hwy 395), a loss of 50% of what existed before 1941.56 There were 43 species of birds, reptiles, and mammals found along Lee Vining Creek, which is similar to the diversity which existed before 1941.57 This diversity, however, is limited to a smaller area than it was before the diversions began.
Restoring the stream to pre-1941 conditions is occurring. Various measures are being used such as rewatering channels, planting trees, and managing flows. These stream restoration techniques should eventually restore the stream to a dynamic, functioning ecosystem.
Mill Creek is the third largest stream in the Mono Basin, carrying 14% of the total runoff.58 Its 18 square mile watershed begins in the Hoover Wilderness at the 12,000 foot peaks above Lundy Canyon,59 and provides an average of 21,200 acre-feet of runoff each year to the stream.60 The watershed also includes a series of connected alpine lakes in Lake Canyon and in the 20 Lakes Basin.
Lundy Lake, a natural lake at the 7808 foot elevation, was enlarged with a dam constructed by the Southern Sierra Power Company in 1911, and now has a 4000 acre-foot capacity and is operated by Southern California Edison.61 Almost all of the water diverted from Lundy Lake for hydropower is not returned to Mill Creek, but empties into Wilson Creek, a much smaller stream which also feeds Mono Lake. Other diversions from Mill creek, mostly above Highway 395, are for pasture irrigation.62 Conway Ranch, Thompson Ranch, and DeChambeau Ranch are the main irrigators in the area.63
Los Angeles Aqueduct Diversion Impacts:
Mill Creek was never diverted into the Los Angeles Aqueduct because its lower flows did not justify the costs of extending the aqueduct through a six-mile tunnel.64 It was still significantly impacted by diversions, however, because of the dropping level of Mono Lake. Above Highway 395, a relatively intact and vigorous stand of nearly continuous willow-scrub, cottonwood-willow, quaking aspen, and conifer-broadleaf habitat exists. The 5000 feet below Highway 395 has much vegetation, but the dropping lake level has caused incision into the streambed that along with channel dewatering from irrigation and hydropower diversions, has degraded the riparian habitat. From 5000 feet below Highway 395 to Cemetery Road, only scattered and degraded vegetation remains. The channel is incised, and the former riparian zone is dominated by scoured cobbles and sagebrush scrub. Below Black Point Road, two diverging channels incised the Mill Creek Delta, with numerous Black Cottonwoods persisting down to the pre-1941 lakeshore.65
The impacts from hydropower and irrigation diversions and dropping lake level have not been rectified, and no stream restoration is taking place. Much of the water diverted for hydropower is staying in Wilson Creek, causing Wilson Creek to incise and erode its banks. Almost no vegetation occurs on Wilson Creek below Black Point Road.66 Water may be returned to Mill Creek in the future, because of the opportunities to restore habitat.
(1)p. 3F-10, Mono
Basin EIR, 1993
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