State Water Resources Research Institute Program

Project ID: 2007WA193B
Title: Lacamas Lake and other Northwest Reservoirs as Bioreactors: How do Dams Affect Downstream Nutrient Transport?
Project Type: Research
Start Date: 3/01/2007
End Date: 2/29/2008
Congressional District: Washington 3rd
Focus Categories: Hydrogeochemistry, Water Quality, Nutrients
Keywords: eutrophication; reservoirs; nitrogen; phosphorus; denitrification; rhodamine
Principal Investigator: Harrison, John
Federal Funds: $ 24,000
Non-Federal Matching Funds: $ 48,275
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 globally. Dam construction and reservoir impoundment is believed to exert an important control on downstream transport of N and P through watersheds, both within Washington State and beyond. However, the effects of individual reservoirs can be quite variable, with some reservoirs decreasing downstream N and P transport and some increasing downstream transport of these nutrients. In general, the within-reservoir processing of nutrients and the factors controlling this processing are not well understood. We propose to use Lacamas Lake in Camas, Washington as a model system to elucidate the mechanisms influencing the seasonal patterns and magnitudes of N and P storage (and removal) within a seasonally stratified, eutrophic reservoir. Located in Clark County, WA, just 20 freeway miles from WSU-Vancouver, Lacamas Lake is a 303d-listed reservoir that currently experiences high rates of N and P input. As a highly impacted (hypereutrophic) system where nutrient processing signals are likely to be large, Lake Lacamas provides an excellent study system to test established theories and gain new knowledge related to N and P retention and dynamics in eutrophic reservoirs. It also provides an excellent springboard for a broader study of reservoir impacts on nutrient transport through watersheds. We will carry out a program of targeted observation combined with dye addition experiments to gain insight into patterns and controls of nutrient cycling in Lacamas Lake, with specific attention to the role of lake stratification on nutrient export. In addition to our focused study of Lacamas Lake, we will also mine existing data from literature and other data sources for information about reservoir nutrient storage and removal. This information will be compiled into a new database containing information on reservoir characteristics and on water quality upstream and downstream from reservoirs as well as within reservoirs. We will use this dataset to examine potential relationships between N and P storage and independent variables such as lake depth, residence time, nutrient loading rates, and trophic status. The work outlined in this proposal directly addresses a water quality issue with direct relevance to ecological and human health. In addition this project will provide crucial new information about how reservoirs process nutrients in watersheds. It also addresses each of the Water Resources Research Act (WRRA) 104B program's goals for training and outreach.

Progress/Completion Report, 2007 PDF

Progress/Completion Report, 2008 update PDF

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