Scientific Investigations Report 2006–5036
U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2006–5036
Increased pressure on water resources in the upper Klamath Basin of California and Oregon for wildlife, irrigation, and power generation has created a need to quantify water availability and use. Water supplied for habitat in wildlife refuges managed by the U.S. Fish and Wildlife Service (USFWS) constitutes a significant water use in the basin. The Bureau of Reclamation’s (BOR) Klamath Project (Project) provides water to both the Lower Klamath and Tule Lake National Wildlife Refuges and also, at times, stores surplus water in the wildlife refuges to augment flow for habitat enhancement in the Klamath River. These refuges use water that is largely irrigation-return flow or runoff from springs and are at the lower, downgradient end of the Project, where excess water is ultimately pumped back into the Klamath River (fig. 1).
As a result of the BOR’s need to carefully manage water provided by the Project to all users, it is important to be able to assess its ability to estimate water use by the refuges with currently available information. In addition, the BOR also is interested in potential ways to improve measurement accuracy of the water delivered to and removed from the Lower Klamath and Tule Lake National Wildlife Refuges to better quantify the overall Project agricultural and refuge water use. To this end, in 2005, the BOR asked the U.S. Geological Survey Oregon Water Science Center to evaluate water use and diversion and return-flow data in the Lower Klamath and Tule Lake National Wildlife Refuges.
The purpose of this report is to present the results of an assessment of the availability of inflow, outflow, open-water-evaporation, and vegetative-evapotranspiration data to estimate water use for the refuges and to provide an approximation of the error associated with the estimates. In the process of estimating water use for the refuges, a description of water routing and management, and therefore the water budget, was formulated and is described herein. A secondary goal of this assessment was to provide suggestions for improved data-collection methods and identify data-collection sites that would help reduce error in refuge water-use estimates.
The scope of this assessment and review was limited to the Lower Klamath and Tule Lake National Wildlife Refuges (fig. 1). The assessment included an analysis of:
Of specific interest was the comparison of measured and estimated water flows to and from the refuges and estimates of open-water-evaporation and evapotranspiration losses from areas of terrestrial and aquatic vegetation. Collection of additional data in the field was limited to a few check measurements of flow; significant data collection was outside the scope of this review. Much of the information evaluated in this review was obtained from the BOR’s Klamath Basin Area Office and the USFWS.
The study area is located near Klamath Falls in southern Oregon and northern California (fig. 1). The Lower Klamath and Tule Lake National Wildlife Refuges are two of six National Wildlife Refuges, managed by the USFWS in the upper Klamath Basin. Established by President Theodore Roosevelt in 1908, the Lower Klamath refuge is the oldest waterfowl refuge in the Nation. Composed of a mix of permanent and seasonal freshwater marshes, open water, grassy uplands, and croplands, it has a total area of approximately 46,700 acres. The refuge is intensively managed to provide feeding, resting, nesting, and brood-rearing habitat for waterfowl and other water birds. Approximately 10,000–12,000 acres of the refuge are leased or farmed cooperatively for cereal grain and alfalfa production. Waste grain, sometimes a set percentage of the harvest, is left on the fields each autumn, and becomes a major source of food for migrating and wintering waterfowl. The Tule Lake refuge was established in 1928 and encompasses approximately 39,100 acres of mostly open water and croplands. Approximately 17,000 acres of these lands are leased to farmers. The two refuges are adjacent to the southern edge of the Project. In total, the two refuges and the Project encompass approximately 240,000 acres.
Prior to agricultural development, the Klamath Basin had approximately 185,000 acres of shallow lakes and freshwater marshes (U.S. Fish and Wildlife Service, 2005). A large wetland marsh and lake covered the region between the Klamath River and the present day Lower Klamath National Wildlife Refuge. Tule Lake was the terminus of the closed Lost River Basin. Unlike other closed basin lakes, Tule Lake was not saline probably because of lake discharge to the ground-water system to the south, allowing circulation through the lake and thus preventing the accumulation of salts and deposition of evaporites.
Beginning in 1905 and continuing through the 1950s, much of the Lower Klamath and Tule Lake wetlands were drained for agricultural development. Today, less than 25 percent of the original wetlands remain (U.S. Fish and Wildlife Service, 2005).
The Tule Lake and Lower Klamath Lake refuges occupy sediment-filled structural basins east of the Cascade Range and north of Medicine Lake Volcano. The downfaulted basins are surrounded by faulted Tertiary and Quaternary volcanic rocks and Tertiary lacustrine deposits (Gay and Aune, 1958). The two refuges are separated by a linear, north-south trending upland with prominent fault escarpments known as Sheepy Ridge, which is composed of Tertiary volcanic and sedimentary deposits. The basin-filling sediment consists of fine-grained lacustrine deposits ranging in age from late Tertiary to Quaternary (Rieck and others, 1992).
For more information about USGS activities in Oregon, visit the USGS Oregon Water Science Center home page.
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