Date: November 16, 2021


  • Melissa Vatterott, Policy Director, Missouri Coalition for the Environment,, (314) 727-0600, ext. 111
  • Elizabeth Hubertz, Director, Washington University Interdisciplinary Environmental Clinic,, (314) 935-8760

St. Louis, MO: Today, the Missouri Coalition for the Environment (MCE) submitted a petition to the Missouri Department of Natural Resources (MDNR) requesting that Missouri’s Water Quality Standards be upgraded. MCE is requesting that MDNR establish water quality criteria for two cyanotoxins, microcystin and cylindrospermopsin, to protect the recreational use of Missouri lakes and reservoirs.

Cyanotoxins are toxic compounds produced by the microorganisms known as cyanobacteria. Under certain environmental conditions such as warmer temperatures, still water, and/or elevated levels of nutrients, cyanobacteria can rapidly proliferate to form harmful algal blooms, known as “HABs.” Exposure to cyanotoxins, which can occur through recreational activity such as swimming or boating, can cause significant adverse health effects on humans, pets, and livestock and in some cases is fatal. 

The federal Clean Water Act delegates to the states the responsibility of developing appropriate water quality standards. Missouri’s current water quality standards, found at 10 CSR 20-7.031, are inadequate to protect against the harmful effects of cyanotoxins and cyanobacteria in lakes and reservoirs. While the majority of states have quantitative water quality guidelines for cyanobacteria, cyanotoxins, or both, Missouri has only qualitative guidelines, consisting of presence/absence tests for the cyanotoxins microcystins and cylindrospermopsin, and no guidelines for cyanobacteria.

“Missouri’s abundant lakes provide many recreational opportunities. Unfortunately, HABs are a growing problem in Missouri and throughout the country. MDNR needs to act decisively to protect Missourians from getting sick from these potent toxins,” said Jared Opsal, Executive Director of MCE. 

In 2019, the Environmental Protection Agency (EPA) released water quality criteria for microcystins and cylindrospermopsin as guidance for states when establishing or revising their water quality standards. The EPA recommended a limit of or below 8 micrograms/liter (μg/L) for microcystins and 15 μg/L for cylindrospermopsin to ensure safe recreation involving water contact. Because Missouri’s water quality standards are lacking, MCE is petitioning for the adoption of the EPA’s criteria for cyanotoxins. 

Once a petition is submitted to the MDNR, the agency has sixty (60) days to issue a response.

MCE is a non-profit environmental advocacy organization based in St. Louis, Missouri. MCE is represented by the Washington University Interdisciplinary Environmental Clinic. Visit for more information.



View MCE’s Fact Sheet on Cyanobacteria here.