Masters Thesis

Suspended sediment deposition in beaver ponds

Suspended sediment was investigated above and below beaver ponds in the Beaver Creek drainage in the south central mountains of Idaho near Idaho City from March 1979 through September 1979. The study was to identify the potential for beaver ponds as settling basins for suspended sediment in wildland watersheds. Two sampling stations were established above and below a beaver colony. The parameters measured included suspended sediment, stream discharge, and water temperature. Also, the beaver pond volumes and surface areas and beaver dam lengths and heights were measured. The data were collected weekly from March through September, except during May and June when sampling was more frequent to bracket the peak flow period. The data demonstrated that suspended sediment was deposited in the beaver ponds. The proportion of suspended sediment deposited in the beaver ponds averaged about 38 percent on the rising limb, 10 percent during the peak flow period, and 65 percent on the falling limb. The suspended sediment ratio was negatively correlated with stream discharge and positively correlated with water temperature. The relationship between the suspended sediment ratio and the stream discharge and water temperature was significant at the 0.05 level. The quantity of suspended sediment deposited in the beaver ponds during the study period was 78.2 tons, which was approximately 25 percent of the suspended sediment load transported through the above sampling station.