Publication Summary

In September and October 2000, the Department of Ecology′s Stream Hydrology Unit conducted geologic and hydrologic reconnaissance and a synoptic-flow (seepage-run) study on the upper Dungeness River in Clallam County, Washington. The study reach lies between the U.S. Geological Survey cable-way gage at river mile 11.8 and the confluence with the Gray Wolf River at river mile 15.9. The study purpose was to evaluate the interaction between the upper Dungeness River and the underlying bedrock aquifer.

In September and October 2000, the Department of Ecology′s Stream Hydrology Unit conducted geologic and hydrologic reconnaissance and a synoptic-flow (seepage-run) study on the upper Dungeness River in Clallam County, Washington. The study reach lies between the U.S. Geological Survey cable-way gage at river mile 11.8 and the confluence with the Gray Wolf River at river mile 15.9. The study purpose was to evaluate the interaction between the upper Dungeness River and the underlying bedrock aquifer.

The synoptic-flow study, combined with the geologic and hydrologic reconnaissance, revealed an overall gain in the river discharge of 7.8 cfs across the four-mile study reach. The study also showed five intermediate gains and four intermediate losses within the study reach, indicating a complex relationship between ground water and surface water. The intermediate gains and losses are attributed to exchange of water within the hyporheic zone, rather than to permanent losses to or gains from bedrock. The overall gain (7.8 cfs) across the four-mile study reach is attributed to gradual (1.95 cfs/mile) ground-water discharge to the river from the bedrock and colluvium along the steep sides of the river valley.