Issues Of The Environment: Mitigating Phosphorus Levels In Area Lakes And In The Huron River
Phosphorus runoff and stormwater overflow have been creating problematic issues in waterways in the Huron River Watershed. While progress has been made, a Washtenaw County Circuit Court ruling will require further regulation to hasten future improvements. In this week's "Issues of the Environment," WEMU's David Fair gets the details from Ric Lawson, watershed planner for the Huron River Watershed Council.
- The Washtenaw County Circuit Court recently decided to require the MDEQ (known since February as the Department of Environment, Great Lakes, and Energy (EGLE) to redevelop a policy implemented in the 1990’s that limits phosphorus discharges into the Huron River.
- The policy, known as the Total Maximum Daily Load (TMDL), aims to reduce the total phosphorus entering the Huron River upstream of and ultimately settling in Ford and Belleville Lakes. The first-of-its kind plan was implemented in response to fish kills and frequent harmful algal blooms in the lakes, fueled by excess phosphorus. Since 1990, the phosphorus concentration limits are set for Ford Lake (50 µg/l) and Belleville Lake (30 µg/l).
- The MDEQ translated these concentration limits into load allocations (i.e. pounds of phosphorus) for each phosphorus source upstream (i.e. WWTPs and for municipal runoff) in Michigan’s first nutrient TMDL in 1996. The WWTPs, affected municipalities, HRWC, and MDEQ formed the Middle Huron Partnership in 1999 to collectively plan for the 50% reduction in phosphorus load needed to meet the TMDL. The partnership continues to this day working on implementation strategies such as creek restoration projects and annual water quality monitoring.
- Since 1996, phosphorus loads going into the reservoirs have dropped by almost 40%. The original policy required a 50% reduction.
- In addition, Ford Lake dam management changes starting in 2008 reduced algae blooms significantly.
- The ruling this year was a favorable response to several municipal waste water treatment plants that had contested the MDEQ’s phosphorus limitations through the courts. After extensive negotiation, the WWTP agreed to honor MDEQ’s phosphorus limitations to receive a permit to discharge while their legal challenge continued. In exchange, MDEQ agreed to redevelop the TMDL.
- The WWTP authorities believed the challenge was necessary for two reasons. First, the TMDL limits were difficult to meet consistently and required expensive infrastructure upgrades at the WWTPs. Municipalities also invested millions of dollars in stormwater and non-point source treatment projects to reduce erosion and limit phosphorus concentrations in runoff. Secondly, in 2003, the University of Michigan’s Dr. John Lehman began studying the lakes’ ecosystem to evaluate phosphorus sources and movement and to determine if a lake management strategy could improve conditions. He concluded that, when lake oxygen levels fall to zero, in-lake processes lead to phosphorus releases from existing lake sediment, which leads to massive algae (or cyanobacteria) growth.
- In addition to cutting phosphorus effluent into lakes, the science in 2011 led the EPA to begin helping state’s enact nitrogen control plans. However, more recent studies have concluded that cutting nitrogen appears to have the opposite effect intended, and algae proliferates by fixing nitrogen form the atmosphere. Therefore, the most recent recommendations from the scientific community for preventing eutrophication in lakes is to limit phosphorus alone. This is much less costly as well.
- Ric Lawson, Watershed Planner for the Huron River Watershed Council, says the improvements to Ford and Belleville lakes have been substantial, but legacy problems remain an issue in meeting target goals.
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