State Water Resources Research Institute Program

Project Id: 2010WA305B
Title: Developing a Novel, Interdisciplinary Approach to Understand Hot Moments in Reservoir Nutrient Transformation
Project Type: Research
Start Date: 3/01/2010
End Date: 2/28/2011
Congressional District: Washington 3
Focus Categories: Nutrients, Hydrogeochemistry, Water Quality
Keywords: nitrogen; phosphorus; reservoir
Principal Investigators: Harrison, John (WSU); Henderson, Stephen M. (Washington State University (Vancouver))
Federal Funds: $ 27,923
Non-Federal Matching Funds: $ 56,480
Abstract: Human-induced nitrogen (N) and phosphorus (P) over-enrichment of surface waters is an important problem in Washington State, throughout the Northwest US, and worldwide, leading to problems such as toxic and nuisance algal blooms, hypoxia, and drinking water degradation. A growing body of evidence indicates that artificial reservoirs play a disproportionately large role in processing of N and P. The reasons for this rapid N and P processing remain unclear, but observations from Lacamas Lake, a hypereutrophic reservoir in Southern Washington, suggest that N and P processing are particularly rapid during dam spills. Rapid processing has also been observed as the waters of Lacamas Lake stratify during late spring.

We propose an interdisciplinary measurement program to quantify and explain rapid nutrient processing in Lacamas Lake during a dam spill event, and during spring stratification. N and P removal will be quantified using lakewide geochemical balances (including novel application of N2:Ar techniques), and using flux-gradient techniques. The flux-gradient technique has not been applied in a freshwater context, and has great potential to resolve spatio-temporal flux variability that is difficult to measure using existing techniques. Strong chemical concentration gradients already measured in Lacamas Lake are consistent with the predictions of flux-gradient theories. To provide physical measurements required for flux-gradient estimates, and to investigate the role of physical processes in N and P processing, high-resolution current meters will measure the turbulent flows that transport N and P to the lakebed.

This project is significant because it is expected to improve our ability to measure, explain, predict, and (potentially) control N removal (and hence downstream N transport) as well as P dynamics in reservoir systems and watersheds more broadly. Clarification of the influence of dam spills on N and P processing would be of particular interest to reservoir managers. This project will also play a key role in strengthening a major NSF proposal on Lacamas Lake N and P processing, which fell just below the funding cutoff on first submission, largely owing to a lack of preliminary hydrodynamic measurements.

The project would address training and outreach goals by supporting the education of a graduate student, and the developing research programs of two junior water-resource scientists. Results would be incorporated into classes, and communicated through ongoing interactions with local stakeholders, including the Lacams Shores community organization and the Clark County Public Works-Water Resources Section. Scientific findings will be communicated through journal publications and a presentation at a major scientific conference.

Progress/Completion Report, 2010, PDF

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