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Bear Creek / Bear Lake (Muskegon County) Watershed Implementation (2) Project: Internal Phosphorus Loading
Current mean total P in Bear Lake = 44 μg/L
Target mean total P in Bear Lake = 30 μg/L
The Bear Creek/Bear Lake subwatershed is a part of the Muskegon Lake Area of Concern (AOC). Bear Lake appears on the Michigan Section 303(d) list of impaired water bodies for excess algal growth and elevated total phosphorus concentrations. These water quality impairments are known to impact both aquatic life and wildlife.
According to the 2008 Total Maximum Daily Load (TMDL), the current annual total phosphorus load to Bear Lake is ~ 3,387 pounds per year, which includes both external (54%) and internal (46%) loadings. The majority of external nutrient loads originate from residential and agricultural land uses within the Bear Creek sub-watershed. The Bear Lake TMDL calls for a total reduction of 56% in annual phosphorus loads, which need to be met via 1) a 50% reduction in external load, and 2) a 79% reduction in internal load to attain the target phosphorus concentration of 30 µg/L in Bear Lake.
The overarching project goal is to reduce nutrient loading to Bear Lake to attain TMDL phosphorus targets. This will be achieved by 1) implementing best management practices (BMPs) to address external nutrient loading and 2) studying internal nutrient loading within Bear Lake to develop a feasibility report for treatment options.
The Steinman Lab is conducting the internal loading portion of the project, which involves:
- Determining accurate internal phosphorus loading rates within Bear Lake, both through internal loading experiments and a modeling approach;
- Estimating seasonal and spatial variability of internal phosphorus loading in Bear Lake; and
- Exploring possible relationships between environmental conditions and internal phosphorus loading in Bear Lake.
Using this information we will evaluate different strategies to reduce internal loading to: 1) meet water quality standards, and 2) remove the eutrophication and undesirable algae beneficial use impairment for Bear Lake, which is necessary to delist the Muskegon Lake AOC.