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Technical Service Center
Environmental Applications and Research Group

Reservoir Monitoring & Research

A mountain reservoirPeople in the Western United States rely on water storage and distribution structures for public drinking water, irrigation, and power production. The Bureau of Reclamation, the largest water supplier in the West, has constructed numerous dams, hydropower plants, canals, and facilities for recreation and environmental protection. Reclamation is working to protect these investments and avoid disruption of services through research and public awareness. Our ongoing reservoir research is an important component of effective facility operation and maintenance. It also helps in the protection and improvement of water quality as well as related environmental, recreational, and fishery values. Here's a glimpse of some of our projects in this area of research:

Lake Mead

Lake Mead is a large mainstem Colorado River reservoir in the Mohave Desert located in Arizona and Nevada. It's lower end is 15 kilometers east of Las Vegas, NV. Lake Mead, formed in 1935 following the construction of Hoover Dam is the largest reservoir in the United States by volume, and is second to Lake Powell (formed by Glen Canyon Dam) in terms of surface area. Lake Mead is made up of four large sub-basins: Boulder Basin, Virgin Basin, Temple Basin, and the Gregg Basin.

The majority of water flowing into Lake Mead comes from the Colorado River (about 98%). The remainder of inflow waters come from the Virgin and Muddy Rivers and the Las Vegas Wash. Retention time in the reservoir is on average 3.9 years, depending on release and inflow patterns. Discharge from Hoover Dam is hypolimnetic and occurs 83 meters below maximum operating level of 364 meters above mean sea level, and its annual discharge is 9 x 109 m3. Each basin within Lake Mead is ecologically unique, and therefore respond differently to the inflow-outflow regime. Furthermore, the different sources of water entering Lake Mead, as in other reservoirs, often retain their identity and influence for substantial distances into the reservoir and do not necessarily mix completely with the rest of the water column. This may lead to significant underestimates of water retention time, transport rates, and fates of materials transported into the reservoir.

Boulder Basin is the most downstream basin and collects the combined flows from the reservoirs two main arms. Additionally, it receives all drainage from the Las Vegas Valley via Las Vegas Wash into the Las Vegas Bay. This drainage includes both non-point surface and groundwater discharges, and treated effluent from all Clark County and municipal wastewater treatment facilities. Boulder Basin is 15 kilometers wide from all Boulder Canyon to Hoover Dam (Black Canyon), and the distance from the confluence of Las Vegas Wash to Hoover Dam is approximately 16 kilometers. The historical Colorado River channel lies along the eastern side of the basin.

Lastly, Boulder Basin serves as a primary source of drinking water for the Las Vegas Valley which includes nearly 1.5 million people. Water from Lake Mead serves nearly 25 million downstream users. In addition, the reservoir is the major outdoor recreation feature of the Lower Colorado River visited by millions of people each year.

Limnological investigations on the Boulder Basin of Lake Mead began in July 1990 and has been continuous thereafter. The purpose of the study is to:

  1. Collect trend data on the influence of the wastewater and other drainage from the Las Vegas Basin via Las Vegas Wash into Las Vegas Bay;
  2. Investigate the status of limnological conditions of Boulder Basin as a source for drinking water;
  3. Perform research into new technology of evaluating limnological features, in particular those related to water quality conditions, of reservoirs; and
  4. Contribute to understanding the ecology of Lake Mead as it relates to the operational scheme of the Colorado River system.

Funding for this project comes from Reclamation's Lower Colorado Region and Reclamation's Technical Service Center.

For more information on the Limnology of the Boulder Basin of Lake Mead, please contact Chris Holdren.

* This report can be found on the North American Lake Management Society's Journal of Lake and Reservoir Management (Volume 13 No. 2., Pp. 95-108, 1997).

Lake Shasta

Lake Shasta is located 12 miles north of Redding, CA, and is part of the Central Valley Project (CVP), a federal water project operated by Reclamation. This reservoir supports a two-level fishery with salmon and trout providing a cool water fishery, and a variety of Centrarchids, notably spotted bass, providing the warm water portion.

One cooperative study that is taking place is the operational effects of a temperature control device on physical, chemical, and biological attributes of Lake Shasta. This particular study is being funded by U.S. Geological Survey's Fort Collins Science Center, Reclamation's Northern California Area Office, and Reclamation's Technical Service Center.

A temperature control device (TCD) was installed on Shasta Dam and began to operate in March, 1997, for the purposes of controlling downstream river temperatures to aid recovery of the endangered winter run chinook salmon, and to minimize loss of generating capacity as a result of releasing deeper, colder water through low level outlet works in order to meet downstream temperature criteria. Prior to operation of the TCD, late summer water temperatures in the Sacramento River were too warm for successful spawning of salmon. Proper operation of the TCD allows surface waters to be released in the spring and early summer, conserving the pool of cold water. As the season progresses withdrawals move deeper into the hypolimnion, and if need be, deeper than the old penstock intakes. Historically, Shasta was operated as a hypolimnetic deep release reservoir. In 1987, however, bypass releases were instituted as a conservation measure for chinook salmon. With the exception of surface withdrawal capabilities, TCD operations are meant to mimic bypass releases.

The current limnological study began in spring 1995, two years prior to operation of the TCD. The objectives of this study are to:

  1. Compare pre-and post-operational changes on the physical, chemical, and biological attributes of Shasta Lake and its tailwaters;
  2. Help develop better operational guidelines for the TCD in order to minimize negative impacts to Shasta Lake while providing optimum water temperatures downstream for chinook salmon spawning; and
  3. Apply limnological, fisheries, and modeling results to existing and planned TCD facilities.

For more information on the TCD study, please contact Davine Lieberman.

Totten Reservoir

Totten Reservoir was built in 1965 to store water from the Dolores River for irrigation purposes. The current project was initiated to determine the quality and quantity of water available to sustain the existing fishery in Totten Reservoir. Available information on water quality and water supply in Totten Reservoir was used to evaluate proposed changes in area water allocations.

Totten Reservoir is currently owned by the Montezuma Valley Irrigation Company (MVIC), although it has not been used for irrigation in recent years. From 1965 to 1986-87, the reservoir was filled with runoff in the spring, with 40 to 45 cubic feet per second (cfs) of Dolores River water being passed through Totten Reservoir from approximately mid-April to mid-July (approximately 5,900 to 6,700 acre-ft/yr). Water was then withdrawn from Totten Reservoir at a rate of about 10 cfs from July to October for irrigation purposes (approximately 1,800 acre-ft/yr). Following the completion of McPhee Reservoir in 1986-87, water was diverted from that reservoir through the Dolores Tunnel and Rocky Ford Ditch to Totten Reservoir following the same schedule as the earlier Dolores River diversions.

Totten Reservoir was taken off-line following completion of the Towoac/Highline Canal in 1992 and is no longer a major part of the regional irrigation system. Since that time, tail- water releases from the Goodland Ditch, return flows and as-requested diversions from McPhee Reservoir have been the major runoff source for Totten Reservoir. The tail-water releases and return flows average about 5 cfs over the period April 15 to October 15. An additional 800 acre-ft/year of water in McPhee Reservoir has been identified as available for release to Totten Reservoir depending on water quality needs.

To learn more about our findings on the Water Supply and Water Quality in Totten Reservoir, Montezuma County, Colorado, and to view the complete report, please visit our publications page.

For more information on Totten Reservoir, please contact Chris Holdren or S. Mark Nelson.