Contributors (in alphabetical order)
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Land and Water UseReservoirsLands surrounding the lower Snake River reservoirs are mainly in private ownership. The only public lands adjacent to the reservoirs are administered by the U.S. Corps of Engineers (USCOE) and isolated parcels owned by the State of Washington. The four lower Snake River reservoirs generally fill the width of the steep-sided canyon, leaving relatively little flat land for cultivation adjacent to the reservoirs. Grassland range is the predominant land cover along the reservoirs. Some relatively small and isolated crop land areas occur on the valley floor and river terraces, particularly toward the western end of the subbasin. The Lewiston Clarkston area is characterized by a concentration of residential, industrial, and commercial land uses. In addition, isolated pockets of urban uses are located in small communities, including Almota, Riparia, and Windust. Unlike many reaches of the Columbia Snake River System, much of the Lower Snake River is not paralleled by highways (Corps 1999). Railroad embankments occupy areas that otherwise might have been suitable for riparian vegetation. TributariesAlpowa CreekAgriculture in the Alpowa Creek watershed and surrounding region is dominated by non-irrigated farming in the uplands, irrigated farming in the lower valleys, and cattle ranching. Grazing is prevalent throughout the Alpowa watershed. Cattle ranching occurred on 51,000 of the Alpowa basin’s 83,000 total acres in 1981, while farmlands cover approximately 27,000 acres, or 33% of the drainage (Soil Conservation Service et al. 1984; USDA 1981). The average size of a farm in Garfield County is 1,750 acres, and 1,933 in Asotin County—three times more than the state averages and as of 1997 had an average net worth of $650,000 each (Washington Agricultural Statistics Service 1997a, 1997b). Grazing has occurred in the riparian areas to varying degrees, and much of the riparian vegetation has been heavily impacted (Mendel 1981; Mendel and Taylor 1981; U. S. Department of Agriculture 1981). The majority of the farmland in the Alpowa watershed is non-irrigated. Mean annual precipitation, length of growing season, and depth of soil largely determine crop production in the watershed. Winter wheat, spring grain, peas, and bluegrass seed are the major non-irrigated crops grown in the uplands of the watershed. Cropping systems most frequently used are winter wheat summer fallow; winter wheat spring grain-summer fallow; wheat-peas; annual winter wheat; annual spring barley; and annual winter barley. Farming occupies the ridge tops and small areas adjacent to the creek. In 1983, agricultural land in the upper watershed was dominated by dryland cropping with winter wheat followed by summer fallow, the cropping pattern that produces the most erosion in the region (Frazier et al. 1983). Proportionally, the watershed contains few irrigated lands (Employment Security Department 1998a, 1998b). Hay, small grains, and pasture are irrigated crops grown in the bottomlands near Alpowa Creek. Where croplands are located adjacent to the channel, the impact from agriculture can be much greater. The earliest recorded observations of the Alpowa watershed described it as “little more than a brook in summer, but its waters serve to irrigate some 300 acres of orchard lands near where it joins the Snake” (Russell 1897). The Pomeroy Conservation District (PCD) has estimated about ten irrigation diversions for irrigating smaller acreage currently exist in the Alpowa watershed. Wheat growers in this region get more economic return from winter wheat than any other crop. Consequently, agencies like conservation districts have had difficulty convincing growers to switch from conventional cropping systems and tillage practices to best management practices (BMPs) such as no-till farming. However, as better farm implements become available and awareness grows about the economics of conservation, growers in the area are slowly beginning to practice more BMPs. A number of efforts are being undertaken in the Alpowa Creek watershed to reduce the impact of farming on the ecosystem. No-till farming is becoming increasingly popular. This method of farming leaves the crop residual on the ground, helping to hold the soil in place and reduce erosion. Other efforts being employed in the area include terraces and buffer strips that help reduce erosion, increase cover for birds and small mammals, and trap nutrients before they reach the streams. In general, little forestry activity occurs in the Alpowa watershed. Timber harvest occurs on portions of the forested upper watershed, but this area is relatively small. As of 1981, only 3,882 acres had been harvested and 504 roaded (Soil Conservation Service et al. 1984). However, interpretation of aerial photos from the early 1990s by the Washington GAP Analysis project indicates that much of the forested land in the watershed continues to be disturbed by logging. Since timber production is not significant in terms of forest surface within the Alpowa watershed, statistics for timber harvest are only available for Garfield County (Table 2). In 1997, 5% of the trees cut were Douglas fir, 1.2% ponderosa pine, 40.4% true firs, 38% miscellaneous conifers, and 15.4% hardwoods. The proportion of products from old growth trees shows that 81% of the 1993 products were from old growth trees. However, this percentage declined sharply to 33% in 1994 and 51.6% in 1995. The variability results from Forest Service policies, because all old growth products came from forestlands under their administration. Products from private owners came only from young growth trees, indicating a lack of quality in forest resources (Washington Department of Natural Resources 1998). Clearcutting has been the usual harvesting technique in this zone, and considering its erosion potential, may contribute impacts to aquatic ecosystems within the Alpowa watershed. Statistics from 1991 to 1993 in Garfield County indicate that 48% of the harvested forestland was logged through the use of clearcutting, and 51% with all kinds of partial cuts. In any case, the total harvested surface was less than 2% of the total forestland of the county (Collins 1997). Deadman CreekHuman activities have significantly changed the terrestrial makeup of the drainage, which is mostly under private ownership except for small parcels allotted to the state of Washington and Bureau of Land Management. The economy of the watershed is based primarily on agricultural production with non-irrigated cropland farming and livestock production as the dominant agricultural enterprises. Table 2. Forest production in Garfield County from 1993-1996 in thousands of board feet (Washington Department of Natural Resources 1998).
The largest land use in the Deadman Creek watershed is crop agriculture (Figure 7). Approximately 97,465 acres or 45% of the drainage is farmed (Soil Conservation Service et al. 1984), with the vast majority of this land non-irrigated. Cropping systems most frequently used are winter wheat—summer fallow; winter wheat—spring grain—summer fallow; annual winter wheat; annual spring barley; and annual winter barley. Most of the irrigated cropland, located in bottomland areas along Deadman Creek and its tributaries are used for hay, small grains and some rotation pasture. Historically, bluebunch wheatgrass (Agropyron spicatum) and Sandberg’s bluegrass (Poasecunda) are thought to have dominated the arid grasslands of which the Deadman Creek ecosystem is a part (Tisdale 1961). These native grasslands were home to a variety of small animals, including white-tailed jackrabbit, sage grouse, and sharp-tailed grouse (Black et al. 1997). The vertebrate distribution model developed the Washington State GAP Analysis program indicates these species are no longer present in the Deadman Creek drainage. 
Figure 7. Land-use type in Deadman Creek watershed (Soil Conservation Service et al. 1984). Since 1900, 94% of the grasslands in the Palouse Bioregion have been converted to crop, hay, or pasture lands (Black et al. 1997). The Southeast Washington Cooperative River Basin Study found only 25% of the vegetation within the Deadman Creek watershed similar to the early seral ecological stage of the potential natural vegetation for the area (Heady and Child 1994). This same area was found to contribute more than 3.7 tons of sediment per year to streams in the watershed (Soil Conservation Service et al. 1984). The dominant vegetative patterns in the watershed as mapped by the Washington State GAP Analysis Project. A number of efforts are being undertaken in the Deadman Creek watershed to reduce the impact of farming on the ecosystem. No-till farming is becoming increasingly popular. Other efforts being employed in the area include terraces and buffer strips that help reduce erosion, increase cover for birds and small mammals, and trap nutrients before they reach the streams. Livestock grazing is the second largest land use in the watershed. A broad-scale analysis conducted by researchers at the University of Idaho on the changes in grass, shrubs, and forest cover types of the Palouse Bioregion illustrates the magnitude of the disturbance. The Deadman Creek ecosystem falls within the southern half of this bioregion, considered to be one of the most endangered in the world. Early settlers grazed their cattle and sheep in an area until they started to lose weight. Such concentrated grazing made possible the invasion of non-native annual species of cheatgrass (Langston 1995). The native perennial grasses were especially susceptible since they evolved without large herds of grazing mammals and the very low summer precipitation increased the grazing pressure at a time when the grasses were stressed (Tisdale 1961). Additionally, cattle selectively grazed the native bunchgrasses, further reducing their population. Once removed, native grasses had difficulty re-establishing without seed sources. Daubenmire (1970) suggested each period of overuse by domestic animals simply reduces the density of the large perennial grasses to a lower level than the preceding, and highly adaptive alien species claim the relinquished territory. Cattle are now grazed on approximately 93,500 acres, or 44% of the Deadman Creek watershed (Soil Conservation Service et al. 1984). This land use occurs predominantly in areas too steep, stony, shallow, or frequently flooded for farming. These same attributes can also make the growth of native vegetation precarious. Cattle are attracted to the succulent forage, shade, reliable water supply, and more favorable microclimate that riparian areas provide. Consequently, improperly managed cattle grazing can be a serious disturbance to riparian areas and thus the cause of deterioration to aquatic ecosystems. Maximizing grazing often involves withdrawal of stream flow or the drainage of wetlands to irrigate and increase available land. Cattle remove protective vegetation resulting in increased erosion, flood flows, and water temperatures (Bauer and Burton 1993). Selected consumption of the more palatable plant species reduces the complexity of the system and the diversity of habitats available to wildlife (Knutson and Naef 1997). Cattle waste reaching the stream increases the nutrient content of the stream sometimes resulting in aquatic plant and algal blooms, and introducing undesirable bacteria. Grazing along stream banks can cause collapse, introducing still more sediment to the stream and changing the channel morphology by increasing stream width, decreasing stream depth, and removing valuable fish habitat (Bauer and Burton 1993). There is direct evidence that cattle are damaging the riparian areas along Deadman Creek. Conditions indicate that the presence of cattle may be a contributor to the decline in aquatic habitat quality. For example, there is no documentation indicating that cattle are being prevented from entering the streams. Fecal coliform levels in Deadman Creek were above the Department of Ecology standard of 100 cfu/100 ml during every month that samples have been pulled. Therefore, it can be presumed that since cattle ranching is a primary land use in the watershed, livestock are able to access the riparian areas, remove vegetation, increase sedimentation, and deposit nutrients into the system. There is little documentation for the implementation of best management practices on the large percentage of private land used for grazing in the watershed. There has been considerable debate within the rangeland science community as to the practical definition of rangeland condition. The traditionally established classification is based on soil quality, forage values, wildlife habitat, and the present state of the vegetation in relation to the potential plant community. More recently, range management has shifted the focus to reflect the percent similarity between the current range site condition and its ecological condition within succession. Using this system, the overall condition of rangelands within the Deadman Creek watershed is rated as poor. |