Algae Blooms and Nonpoint Source Pollution

Algae Blooms and Nonpoint Source Pollution

The water quality of the Kalamazoo River has greatly improved since passage of the Clean Water Act in 1972 and subsequent implementation of sewage treatment technology.  Many communities and industries throughout the region have continuously worked to improve water quality by taking measures to reduce sources of pollution to the river. And yet there are still periodic problems with algae blooms and poor water quality during spring and summer months in reservoirs along the Kalamazoo River.

Nutrient enrichment of reservoirs along the Kalamazoo River is one of the major water quality problems in the watershed.  Lake Allegan is of particular concern and has been highly studied and scrutinized by state and federal authorities.  This 1,650-acre impoundment on the Kalamazoo River sits approximately 30 miles upstream of Lake Michigan.  It is considered extremely nutrient-enriched which causes problems like algae blooms, low dissolved oxygen, odor and aesthetic issues, difficulties for fish and wildlife, and ultimately impacts recreation. 

In the late 1990s, the State of Michigan conducted a study and set specific limits on nutrients that can be discharged into the river because of the algae and other associated problems caused by excess nutrients.  The main nutrient of concern is phosphorus, an essential element needed for plant growth, but too much of it can cause algae and other aquatic plants to grow out of control.  The program designed to address problems of nutrient enrichment is referred to as the “Total Maximum Daily Load” or TMDL.  The goal of the TMDL is to reduce common sources of phosphorus from getting into the river.  The most common sources come from waste water treatment plants, agriculture, and urban stormwater.  Community waste water systems and industries discharge treated water into the river that contains phosphorus.  Erosion and runoff from farm fields and feed lots can be a source of phosphorus to ditches, streams, and lakes.  And runoff from parking lots, driveways, lawns, and buildings washes phosphorus and sediment into storm drains and local waterways.

The phosphorus TMDL for Lake Allegan and the Kalamazoo River determined that an average in-lake total phosphorus concentration of 60 micrograms per liter for Lake Allegan from April-September would be necessary to improve water quality conditions.  Using average flows for the river, this translates to a phosphorus loading goal of 18,500 pounds per month from April-June and only 10,800 pounds per month from July-September.  (This is further broken down into waste load allocation for point sources set at 8,700 pounds per month from April-June and 6,700 pounds per month July-September.  The load allocation for all nonpoint sources is 9,800 pounds per month April-June and 4,100 pounds per month July-September).

Point sources in the watershed typically discharge at or below the waste load allocation.  It is the nonpoint source contribution of phosphorus that has yet to be controlled.  The Kalamazoo River Watershed Management Plan was created to develop strategies to address problems with nonpoint source pollution.  Residents and land owners are encourage to visit the River Wise page to learn more about what each of us do at our own home to reduce pollution to the river and in-lakes.

Learn how you can act on behalf of the Kalamazoo River Watershed Council today!