May 1997
Sumps Sump habitats are a combination of permanently flooded wetland and open submersed vegetation. Vegetative types are similar to those listed above for permanently flooded wetland and open submersed habitat found on Lower Klamath NWR and consist primarily of emergent plants such as hardstem bullrush and cattail and submersed plants such as sago pondweed. The area is used primarily as staging and roosting habitat for geese and ducks. These include snow geese, white-fronted geese, and cackling Canada geese, in addition to canvasback, ruddy ducks, American widgeon, and lesser scaup. The area is also used extensively by considerable numbers of eared and western grebes. A complete list of wildlife species found in these areas is listed in Appendix C.
While the majority of plant and animal species resembles those found on Lower Klamath NWR, plant and animal diversity on the Tule Lake sumps is considerably lower. This is due to degradation from siltation, stabilized water levels, and poor water quality (Mauser 1994).
Berms Berms refers collectively to roadsides, ditchbanks, and the flat areas between irrigation ditches and drains. Berm vegetation consists primarily of weeds, predominantly bassia, kochia, perennial pepperweed, stinging nettle, and Canada thistle. Grasses exist in certain places and are composed primarily of wheatgrass species. This is the only upland habitat excluding cropfields that exists near the sumps on Tule Lake NWR. Consequently it is used extensively as hiding cover for pheasants, rabbits and small rodents, and as nesting cover for pheasants, mallards, teal, gadwall, rabbits and small rodents. However, the area would have considerably more wildlife potential if the predominant weed species (bassia and kochia) were controlled and replaced by forbs and grasses.
Peninsula Area The peninsula is isolated with no public use allowed. It contains the two remaining upland habitat types found on Tule Lake NWR (see Figure 3). The first upland type consists primarily of cheatgrass, Idaho fescue, basin wildrye, rabbitbrush and sagebrush. It has considerable vertical cliff faces supporting nesting and roosting sites for barn owls, redtail hawks, American kestrels, prairie falcons and golden eagles. It is a major barn owl roost and contains the only golden eagle nest on refuge. Other wildlife species found in the area include jackrabbits, cottontail rabbits, coyotes, and mule deer.
The second of these upland habitats is composed primarily of sagebrush, rabbitbrush, and scab rock. It has very little soil consisting primarily of clay. Wildlife species found on this area are similar to the aforementioned upland habitat.
Lower Klamath NWR is the most productive waterfowl refuge in the Klamath Basin NWR complex and contains the bulk of the 411 species of wildlife occurring on the complex. Most species occurring on the refuges are dependent on wetlands, waterfowl being the most conspicuous. During fall and spring migration, up to 1 million waterfowl rest and feed on these refuges. In recent years, over 60 million waterfowl use days[2] per year have been recorded . Despite a general reduction in the number of waterfowl along the Pacific Flyway, waterfowl use of Lower Klamath has remained stable or increased over the past 15 years while waterfowl use on Tule Lake NWR has decreased.
In addition to waterfowl, Lower Klamath NWR is important to a variety of vertebrate species of federal and/or state concern (Table 2). Bald eagles that originate in the Pacific Northwest and western Canada are the most numerous of the threatened and endangered species on the refuges. Populations have been steadily increasing to the peak of over 1,100 eagles during the winter of 1991-92. Bald eagles are attracted to the refuges by large populations of waterfowl and rodents. Rodents are eaten in large numbers by eagles when Lower Klamath refuge farm units are pre-irrigated during the fall and winter. Peregrine falcons are also present on the refuges and prey on waterfowl and shorebirds. Although the shortnose and Lost River suckers are present on Tule Lake NWR and the Klamath River, no suckers have been found on Lower Klamath refuge; however, they are suspected to occur in Unit 2 (see Figure 2).
The refuges are host to several species of colonial nesting waterbirds. American white pelicans (which nest in Sheepy Lake Unit 2 - Lower Klamath NWR) are one of the last two colonies remaining in California (the other being at Clear Lake NWR). White-faced ibis are also an important nesting species on the refuges. Ibis numbers have grown over the past several years to the present nesting population of approximately 3,800 pairs located in five colonies (USFWS 1994a). Ibis nest in association with great egrets, snowy egrets, and black-crowned night herons. These refuges are an important area to neotropical migratory birds, especially those dependent on wetland habitats (Appendix C).
Vertebrate Animal Species at Risk Refuge managers believe that on Tule Lake NWR "a lack of habitat diversity has led to reduced wildlife species diversity" (U.S. Fish and Wildlife Service 1994). However, very little information exists (outside of waterfowl inventories) that indicates present or past population trends or species diversity on NWR lands. For these reasons the list of species at risk found in Table 2 refers to threatened, endangered, candidate, and sensitive species as identified in the Habitat Management Plan Lower Klamath National Wildlife Refuge (U.S. Fish and Wildlife Service December 1994).
The water resources of Lower Klamath and Tule Lake NWRs are directly linked to the agricultural activities within the irrigated lands of the Klamath Basin (Figure 1). Reclamation has been responsible for the administration of the 1905 Klamath Reclamation Project. Most of the wetlands have been drained and the Lost River dammed, diverted, and modified to provide for agricultural uses of the basin under the Project.
Historically, Tule Lake wetlands fluctuated greatly from year to year depending on regional precipitation. At times the Tule Lake wetlands covered more than 100,000 acres (Abney 1964). Today the Tule Lake NWR is 39,116 acres, with 13,240 acres of remaining wetlands called Tule Lake sumps 1-A and 1-B (Mauser 1994). The remaining area of the Tule Lake NWR is dedicated to agricultural uses and grain crops for waterfowl feeding grounds.
The Tule Lake wetland sumps receive their water from return flow irrigation. Water levels within the sumps have been stabilized to prevent flooding. The Tule Lake Tunnel (a concrete-lined 6,000 feet tunnel) was constructed to help in the water level stabilization by conveying drainage from the Tule Lake sump to the Lower Klamath NWR. The tunnel enabled irrigation managers to maintain a consistent water level within the Tule Lake sumps by moving as much as 300 cubic feet of water per second through the tunnel. This transfer of water from Tule Lake to Lower Klamath has given renewed life to the Lower Klamath wetlands.
In the early- and mid-1900s, the Lower Klamath NWR and adjoining lands were cultivated. However, the build-up of alkaline soils limited the agricultural potential in the Lower Klamath Lake area. Historically, the Lower Klamath wetlands covered about 80,000 acres. Using the water from the Tule Lake tunnel, approximately 25 percent of the original Lower Klamath wetlands, or about 20,000 acres, have been restored to wetland habitat. Current practice of the Service at the Lower Klamath NWR is to have both shallow and deep water wetlands with interspersed "islands of vegetation." This provides varied habitat for wildlife.
[2] Any waterfowl using the refuge for one day = 1 waterfowl use day.
Return to the IPM Plan Table of Contents or continue on to 3. Current Water Resources of Tule Lake and Lower Klamath NWRs