Spring Lake Phosphorus Project

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Historically, field measurements of phosphorus concentration in watersheds have concentrated on the "external" loading of phosphorus. External loading refers to the nutrients contributed by point and nonpoint sources entering into a waterbody. Phosphorus being released by the sediments at the bottom of a waterbody, or "internal" loading, is often not measured. However, in highly eutrophic lakes such Spring Lake, internal loading can account for a substantial amount of the total phosphorus load. Many studies have shown that reductions in external load do not limit algal growth because of the counteracting release of phosphorus by sediments.

Restoration of lakes with high internal loading may involve the application of a chemical to bind the phosphorus to the sediments. Previous studies have shown that the application of alum (aluminum sulfate) can reduce internal loading and its effectiveness lasts about between 4-20 years, depending on lake conditions.

AWRI has been contracted by the Spring Lake - Lake board through Progressive AE to research the internal loading of phosphorus in Spring Lake. One experiment was completed in 2003, and two additional experiments were completed in 2004. Field application of alum to Spring Lake is taking place in October and November, 2005, and AWRI conducted an assessment of the effectiveness of the alum application in 2006.

See Project Information, Project Products, and Contacts for more details.