Vertical Hydraulic Gradient at the Sediment-Water Interface in Upper Klamath Lake

Science Center Objects

"The goal of this project is to characterize the vertical hydraulic gradient at the sediment-water interface in Upper Klamath Lake."

Management of Upper Klamath Lake depends on adequate knowledge of inputs to the lake of both water and nutrients. Loadings of phosphorus and other nutrients to Upper Klamath Lake lead to dense, harmful algal blooms during the summer and degrade water quality and stress endangered fisheries. In 2002, The Oregon Department of Environmental Quality (ODEQ) established a total maximum daily load (TMDL) management model that targeted a 40 percent reduction in phosphorus loading to Upper Klamath Lake from external sources in the drainage. It is also recognized that flux through the lake’s sediment is a potentially important but as yet uncharacterized source of phosphorus loading to the lake (“internal loading) that may help trigger and sustain algal blooms. In order to manage and restore lake water quality it is necessary to understand the processes that contribute to internal phosphorus loading and their relative magnitudes.

The goal of this project is to characterize the vertical hydraulic gradient at the sediment-water interface in Upper Klamath Lake and identify any spatial or temporal variability.

We collected direct measurements of hydraulic head in the lake and in the lake sediments at 10 locations from May to October 2017. We use this data to calculate the vertical hydraulic gradient at these locations over the study period. The gradient data provided by this study will help refine estimates of the advective groundwater transport component of the overall water budget for the lake and internal phosphorus loading in Upper Klamath Lake.