Comparative examination of Lake Spokane groundwater for nutrient discharge by residential development influence
Date of Award
Master of Science (MS) in Biology
"The goal of this study is to support the implementation of the Total Maximum Daily Load regulation for the Spokane River and Lake Spokane area in Eastern Washington in partnership with United States Geologic Survey and the Washington State Department of Ecology. The influence of residential development along the north shore of the Lake Spokane reservoir in the Suncrest area was examined as a possible nonpoint source of nutrient contamination to shoreline groundwater and as a possible influence on algae growth in Lake Spokane. Surface water and groundwater samples from hand-driven piezometers were collected from three residential development categories. The three categories were distinguished by proximity to residential development and onsite septic systems in relation to the shore line of Lake Spokane: nearshore, terrace and undeveloped/reference. Samples were taken monthly from March through August 2015. Groundwater samples were analyzed for chloride, ammonium, nitrite plus nitrate and orthophosphate through the Washington Department of Ecology's Manchester Laboratory. Surface water samples and a subset of groundwater samples were analyzed for ammonium, nitrite plus nitrate and orthophosphate through Eastern Washington University. Groundwater from areas of residential development in March/April 2015 was significantly higher in nitrite plus nitrate and groundwater from nearshore residential development was significantly higher in orthophosphate in August 2015 (p-value 0.05). This indicates that residential development may be impacting groundwater nutrient concentrations. In conjunction with groundwater sampling, algae growth response to groundwater taken from the three development categories was compared using Anabaena sp. as a bioassay indicator for relative nutrient contents. There was significantly higher daily chlorophyll change in groundwater from the nearshore than reference development categories (p-value <Ì² 0.05)"--leaf 1.
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Plastino, Wyatt, "Comparative examination of Lake Spokane groundwater for nutrient discharge by residential development influence" (2016). EWU Masters Thesis Collection. 396.
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