Glossary of terms

Lappin, J.L.; Clark, W.H.; 1985, Preliminary Assessment of Water Quality Impacts of Recreational Housing and Livestock Grazing in the Cascade Reservoir Watershed. Unpublished Report, Boise ID, 21 pp. A preliminary assessment of impacts on water quality in Cascade Reservoir from recreational housing and livestock grazing. Sampling sites were identified on streams along the southwest shores of the reservoir. Samples for nutrients and fecal coliform bacteria were collected upstream from the area of subdivisions (baseline), downstream of the subdivision areas but upstream of the grazing areas (human impact only), and at the reservoir, downstream of both the subdivision areas and the grazed areas (total impact). Samples were collected at time periods representing high human use (after holiday weekends) and both high (spring runoff) and low (late summer) flow volumes. The late summer sample was scheduled to be near the end of the grazing season. 60% of the spring runoff (May 1985) samples showed increased fecal strep and coliform levels at both the subdivision and reservoir levels (Table 1, Figure 2). The control stream sample showed no significant increase over baseline. All of the late summer (September 1984) samples showed increased fecal strep and coliform levels, including the control stream (Table 1, Figure 2). A detailed literature review is contained within this report which covers studies of both the Cascade area and other similar systems. A review of available literature on human and livestock bacterial contamination and transport through a variety of soil systems is also detailed. The literature findings support those of this study. Spring runoff samples also showed increased ortho and total phosphorus levels at both the subdivision and reservoir levels (Table 2, Figure 3). Observed increases are broken down by sample site and phosphorus state. Late summer samples also showed increases in both ortho- and total phosphorus (Table 2, Figure 3). Nitrate-nitrite and chloride levels did not increase over background at any downstream sites at either sampling period. Literature reviews of nutrient loading and transport from both human and livestock are detailed, and support the findings of this study. Findings showed a noticeable increase in both bacterial and nutrient concentrations from recreational subdivision impact, however; increases were greatest in areas impacted by grazing activities. The mitigation of grazing activities and evaluation of ground water contamination necessitating installation of a central sewage collection system are recommended. While limited in time and area, this study represents an efficient evaluation of water quality impacts and source delineation. Literature cited and reviewed is an excellent resource.