Stormwater monitoring and pollutant assessment in Mackinaw City, Michigan.

Abstract

Stormwater pollution has become an increasing threat due to increases in impervious surfaces, and the destruction of wetlands. Mackinaw City is a high traffic destination, located in the northern Lower Peninsula of Michigan, yet little is known about stormwater runoff in this area. In this study, we conducted stormwater monitoring to assess the concentration of pollutants entering the Great Lakes from stormwater monitoring. We quantified average impervious surfaces in the city using GIS. To conduct stormwater monitoring, we collected water samples for water chemistry from 6 sites (Chloride, sulfate, phosphorous, nitrate, chlorophyll-a) following a rain event on July 21, 2016. In addition, we measured physical parameters of the water (temperature, pH, dissolved oxygen, conductivity, and turbidity). Macroinvertebrates were also collected to indicate the degree of pollution at each outfall. Our sample area in Mackinaw City was 45% impervious surfaces, while Mackinaw City overall was 17% impervious surfaces. Overall, Mackinaw City showed signs of pollution that differed depending on apparent land use around each outfall. HBis from macroinvertebrate sampling suggested the water quality was poor in three sites, and likely nutrient polluted, although water chemistry data did not support this in the sites macroinvertebrates were sampled.