Lawmakers will wait a month before considering controversial changes to Kentucky’s water quality standard for a substance called selenium.

Selenium occurs naturally in small amounts, but is released in heavier doses by some coal mines and can cause deformities in fish. There are currently two standards for selenium in water: one based on short-term exposure and another for long-term exposure. The proposal from the Kentucky Division of Water would essentially get rid of the first standard, and change the way the second is measured.

Department for Environmental Protection Commissioner Bruce Scott says many other states have already gotten rid of the short-term standard, because it’s been overturned by courts. He says the proposed changes will provide more protection for Kentucky waterways.

“Even EPA in all of its information has determined that water column toxicity for selenium really isn’t the issue,” he said. “You don’t necessarily have a water column concentration that leads to lethality of fish.”

Instead, the new standard will measure the selenium in fish tissue, rather than in the water. But environmental groups say the changes don’t make sense. Bev May is a member of Kentuckians for the Commonwealth, and lives near several surface mines in eastern Kentucky.

“If you look at the streams that are coming from mountaintop removal sites, you’re not going to see a lot of fish to test. They’re dead already,” she said. “So it seems to be a completely unworkable plan to me.”

May and others who spoke at the meeting of the Administrative Regulation Review Committee say the changes have been rushed and provide no transparency. Now, the decision is delayed for a month in order to get more public comment. If the new standards pass through that committee in March, the proposal will go before the Joint Committee on Natural Resources and the Environment. If lawmakers sign off on it, the new standards will become law in Kentucky—though the Environmental Protection Agency still will eventually have to approve the standard.