EARLY HEARING DETECTION AND INTERVENTION VIRTUAL CONFERENCE
MARCH 2-5, 2021
(Virtually the same conference, without elevators, airplane tickets, or hotel room keys)
5/23/2019 | 3:00 PM - 3:15 PM | WHEN THE PROBLEM DOESN’T WASH AWAY: PHOSPHORUS BUDGET OF INTERNAL AND EXTERNAL LOADING STUDIES AND NUTRIENT BIOASSAY IDENTIFY WATERSHED RESTORATION GOALS | 254 B
WHEN THE PROBLEM DOESN’T WASH AWAY: PHOSPHORUS BUDGET OF INTERNAL AND EXTERNAL LOADING STUDIES AND NUTRIENT BIOASSAY IDENTIFY WATERSHED RESTORATION GOALS
Spring Lake is a drowned river mouth lake that historically has contained some of the highest phosphorus concentrations in western Michigan lakes. A 2005 alum treatment effectively reduced internal phosphorus loading in the lake, although water column concentrations exceeded restoration targets. Internal loading studies conducted in 2005, 2006, 2011, and 2016 suggest alum may be starting to lose effectiveness. Concern that high phosphorus loads may be entering the lake from the surrounding watershed prompted an external loading study of the main tributaries of Spring Lake. The results of internal and external loading studies, combined with work from earlier researchers, were used to estimate total load and generate an annual phosphorus budget for Spring Lake. The proportion of the total load contributed by tributaries more than doubled from 22% pre-alum application to 46% post-alum. A complementary nutrient bioassay in Spring Lake, with a control treatment as well as treatments of 10X ambient concentrations of nitrate, phosphate, and both nitrate and phosphate, indicated that changes in chlorophyll concentration were co-limited by nitrogen and phosphorus; future nutrient management must focus on both nutrients in the Spring Lake watershed.
- Eutrophication
- Watershed
- Management
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Presenters/Authors
Michael Hassett
(), Annis Water Resources Institute - Grand Valley State University, hassetmi@gvsu.edu;
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Maggie Oudsema
(), Grand Valley State University - Annis Water Resources Institute, oudsemam@gvsu.edu;
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Alan Steinman
(), Annis Water Resources Institute-Grand Valley State University, steinmaa@gvsu.edu;
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