Total Maximum Daily Load

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Jennifer Lawson
Water Quality Manager
301 E Huron St., 4th Floor
P.O. Box 8647
Ann Arbor, MI 48107​
734.794.6430, x43735

​Federal and state laws mandate that all surface waters be protected for a full range of designated uses. These uses are:

  • Agriculture
  • Industrial water supply
  • Public water supply at the point of intake
  • Navigation
  • Warm water fishery (or cold water fishery, where applicable)
  • Other indigenous aquatic life and wildlife
  • Partial body contact recreation
  • Total body contact recreations between May 1 and October 31

When a lake or stream does not meet its designated uses, it is considered "impaired" and a Total Maximum Daily Load (TMDL) must be developed. A TMDL quantifies how much of a pollutant a water body can assimilate, or accept, without violating water quality standards. In addition, a TMDL establishes pollutant reduction targets necessary to restore and maintain the designated uses.

Huron River TMDLs

Many surface waters in the Middle Huron Watershed do not meet these designated uses. TMDLs for the Ann Arbor area include:

Ford and Belleville Lakes (Phosphorus)

Phosphorus is an essential nutrient for plant, algal, and animal growth that occurs naturally in the environment. However, in excess amounts, phosphorus stimulates high plant and algae growth, significantly reducing the aesthetic, recreational, and ecological quality of surface waters.

The City of Ann Arbor and other permit partners are working collaboratively to address the phosphorus TMDL. Excess phosphorus in Ford and Belleville Lakes, much of which comes from the upstream watershed, contributes to severe algal blooms during summer months.​

Argo Pond to Geddes Pond (E. coli )

Escherichia coli (E. coli) is a group of fecal coliform bacteria found in the lower intestine of warm-blooded organisms such as humans, wildlife, and domestic animals. The presence of E.coli in a ​lake or river indicates the water has been contaminated by fecal material from animals or humans.
A 2007 study by the Washtenaw County Water Resources Commissioner found that urban wildlife (namely raccoons) and pets (namely cats) are significant sources of E.coli to Geddes Pond. Based on completed sampling, it does not appear that illicit connections to the storm sewer are significant sources of E.coli.
Strategies for reducing E.coli inputs are included in the example strategies include: 
  • Identifying and eliminating cross connections between sanitary sewers and storm sewers through the illicit discharge elimination program.​
  • Encouraging pet owners to clean up after their animals through public education, signage, and placement of pet waste disposal bags in city parks.
  • Modifying habitat to discourage urban wildlife. For example, establishing tall grasses, shrubs, and trees makes ponds less attractive to Canada geese.

Malletts Creek (Biota) 

The biota TMDL for Malletts Creek specifically addresses warm water fish and macroinvertebrates, or aquatic insects. Malletts Creek does not support healthy fish or invertebrate communities due to excessive storm water runoff, streambank erosion, sedimentation, and unstable flows (i.e., very high and very low flows). High impervious surface in the creekshed contributes to the poor conditions observed in Malletts Creek. ​

Swift Run (Biota)​

The TMDL for Swift Run addresses macroinvertebrate communities. High imperviousness in Swift Run creekshed contributes to flashy flows, bank erosion, and sedimentation problems in the stream.​

How are the TMDLs being addressed?​

Middle Huron River Watershed partners submitted a TMDL plan (PDF)) as part of the watershed storm water​ permit. Monitoring is an important component of the TMDL plan. Partners are monitoring the river and its tributaries to:

  • Locate phosphorus sources as specifically as possible
  • Identify hot spots for pollutant loading
  • Understand nutrient dynamics in the tributaries
  • Prioritize projects throughout the basin.
This extensive monitoring will enable Middle Huron communities to target implementation activities for maximum benefit. The Huron River Watershed Council (HRWC) carries out much of the monitoring on the Middle Huron. More information, including monitoring reports, can be found on HRWC's Middle Huron Program website.​​

Additional Resources

Environmental Protection Agency (EPA)

Michigan Department of Environmental Quality (MDEQ)