The upcoming water recreation season in Michigan will be the first with a statewide total maximum daily load (TMDL) in place for E. coli — a bacteria that indicates pollution by fecal material.
The TMDL requires actions to lower E. coli levels in waters known to have excessive amounts of the bacteria. E. coli can cause problems ranging from diarrhea to kidney damage, if accidentally ingested. Health-related beach closures are often due to high E. coli levels.
"Routine testing has shown that E. coli levels in many areas in Michigan are above the surface water quality standard," said Molly Rippke, an aquatic biology specialist in EGLE's Water Resources Division. "When that standard is exceeded, the risk to human health while contacting or ingesting water is higher. The federal Clean Water Act requires Michigan to develop a TMDL to provide a framework for restoring water quality. Because this is a widespread problem, the statewide approach will be more efficient and allow EGLE staff to focus on fixing problems rather than writing TMDLs."
Sources of E. coli include failing septic systems, livestock, pets, and nuisance levels of wildlife. To meet the standards in the new TMDL, state regulators will require large livestock operations, municipal stormwater systems and others to reduce the amount of E. coli discharged to waterways.
The goal of the TMDL is to meet the E. coli water quality standard and the total and partial body contact designated uses in each water body. The daily targets are 300 E. coli per 100 milliliters (mL) from May to October and 1,000 E. coli per 100 mL the remainder of the year.
The statewide E. coli TMDL was approved by the U.S. Environmental Protection Agency in 2019 and applies only to waters known to have elevated E. coli levels. As new impaired waters are found, they will be proposed as new additions.
"TMDLs are a necessary first step in solving E. coli pollution problems," Rippke added. "The TMDL will allow EGLE to implement needed pollutant reductions from point sources. Addressing nonpoint source reductions to make our waters safer for residents and visitors will require cooperation from other agencies and the public."
Visit the statewide E. coli TMDL website for more information on the TMDL, EGLE E. coli website for general information, check out the E. coli factsheet and watch the MI EnviroMinute video on the subject.