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Idaho Clean Water Protections

A trout fishing stream.

Idaho’s rivers, lakes and streams support wildlife such as native trout.

Robert Cicchetti / Shutterstock

What’s at Stake

Idaho, at the behest of its phosphate industry and others, asked the U.S. EPA for permission to discharge polluted water into state waterways. The EPA agreed to this proposal, endangering some of the state’s most pristine waters. Earthjustice sued under the Clean Water Act.


This case challenged the U.S. Environmental Protection Agency’s approval of weak Idaho state water pollution rules that didn’t adequately protect Idaho’s cleanest rivers, lakes and streams including cold-water streams that support native trout. These are waters that are the cleanest and best suited to support fisheries and recreation.

In July 2013 the U.S. Environmental Protection Agency announced an about-face on Idaho's request to skirt environmental regulations on its highest-quality waters.

States are allowed to make and enforce their own rules preventing water pollution as long as they comply with requirements of the federal Clean Water Act. But Idaho’s new rules failed to do this, even though the EPA gave its blessing to them.

The Clean Water Act requires limits on individual discharges of pollution into waterways; for instance, pipes dumping sewage into a river or lake. It also requires rules that protect water quality from being degraded by the cumulative effect of many legally permitted pollution sources whose combined pollution may harm the river or lake.

Under Clean Water Act regulations, the quality of these waters must be protected unless degradation is necessary for “important economic and social development” in the area. In these limited situations when degradation is allowed, a state is still required to fully protect the water body’s existing uses. Idaho’s rules fail to ensure that polluting actions undergo review to determine the actions are actually necessary, which will allow more degradation of Idaho’s high-quality waters than the Clean Water Act allows.

The Greater Yellowstone Coalition served as co-counsel on this case.

Case ID


Case Updates

August 4, 2013 | In the News: Seattle Post-Intelligencer

EPA reverses course, nixes Idaho pollution rule

The U.S. Environmental Protection Agency has rejected a rule written by Idaho’s Department of Environmental Quality that would have allowed polluters to dump new pollution into the state’s waterways without review. The rule, which exempted activities such as mining from critical oversight, could have produced serious health risks by permitting polluters to discharge toxic chemicals that accumulate in the environment and in food chains.

July 25, 2013 | Legal Document

EPA Letter, TSD Enclosure

EPA strikes down Idaho's Clean Water Act de minimus program, says not protective enough of Idaho's most pristine waters