COLUMBIA — The Environmental Protection Agency is prodding the state of Missouri to impose a stricter E. coli bacteria limit for 20,000 miles of water where people swim.
The current limit for these streams is more than twice the level the EPA recommends to protect public health.
These streams are classified for "whole body contact," or swimming, but the state says they are infrequently used. In some cases this is because they lack a year-round flow.
The new limit brings the level of E. coli bacteria allowed in these streams down to 206 colony-forming units per 100 milliliters of water. This level has the EPA stamp of approval and decreases the risk that someone might get sick from swimming. With this limit, the odds of a swimmer getting sick are 1 in 100, state Water Quality Monitoring and Assessment Chief Phil Schroeder said.
Robert Lerch, a soil scientist with the U.S. Department of Agriculture, said the new limit sounds stringent, considering some of these streams might not exist year-round.
"That is a pretty reasonable standard. It's pretty protective," Lerch said.
The new limit represents a balancing act between protecting public health and minimizing the cost to sewer districts.
Because of the new limit, 70 public wastewater treatment plants may have to disinfect what they discharge into streams. Schroeder estimates this will cost wastewater treatment plants in Missouri about $8.5 million to install disinfection systems and $4.7 million yearly to operate them. Dischargers would have up to three years to comply with new limits.
Tom Ratermann of Boone County Regional Sewer District said he doesn’t think the new limit will affect the district’s operations, because the district is already planning for major upgrades.
Funded by a $21 million bond issue approved by voters in April, the district plans to close about 25 treatment facilities, consolidate operations and add disinfection equipment to five facilities. The disinfection equipment costs about $2 million. The construction needs to be complete by Dec. 31, 2013.
“I think our plan is still sound,” Ratermann said.
John Ford of the Natural Resources Department said the new limit means the state’s 2008 list of impaired waters will see some changes. The list, which must be submitted to the EPA every two years, was drawn up using the old limit. A first draft of it was circulated in September. Ford said he hopes a revised version of the list that takes into account the new limit will be before the state's Clean Water Commission in March.
The state has been overhauling its water quality standards for the past three years. Last year it made changes to which streams it classified for whole body contact, making them subject to the stricter regulations. The new limit is another step in this process.
"The EPA has been after the state really for the past 30 years, since the Clean Water Act," Lerch said. "We are one of the last states to develop more rigorous whole body contact standards."
The state has also moved to a system of water quality standards based on the amount of E. coli bacteria in the water, not fecal coliforms. According to the EPA Web site, E. coli is a better indicator of pathogens that can make people sick, but some states still judge water quality by measuring fecal coliforms.
In Missouri, water quality standards dictate E. coli limits for the stream. But for now, sewage permits specify fecal coliform limits. Rattermann said he's concerned about changing the permit specifications from fecal coliform to E. coli.
“The big question for wastewater operators is how will our current and proposed equipment perform to achieve an E. coli standard?” Ratermann said.
Ratermann said there is more data on how equipment can reduce fecal coliform amounts in discharge rather than E. coli.
“Measuring E. coli requires more complex lab equipment. It becomes a bit of a capacity problem," Ratermann said. "At the sewer district, we've been outsourcing some of the lab work, and there aren't many labs in mid-Missouri that perform testing for E. coli."