A lake is a passive collector that sits at a low point in the landscape and accumulates water and materials that flow into it. The water and materials are retained in the lake until they are discharged to a point lower in the landscape. As a result, waterbodies are heavily affected by runoff from their watershed. Stormwater runoff carries pollutants such as sediments, roadway grease, fertilizers and excess nutrients into bodies of water with little to no filtration. Stormwater runoff is one of the leading causes of poor water quality in lakes, rivers, streams, and ponds.

A watershed evaluation consists of identifying every single inlet to the lake, big and small, during a rain event. At each inlet, we record its size and flow rate and collect a water sample to test for nutrient concentrations. Looking at the amount of water each inlet carries, together with the nutrient concentrations of each inlet, we determine which inlets carry the highest nutrient loads. We then recommend actions for reducing nutrients in these problem inlets and oversee the rectification process.