Bear River in Idaho. Federal standards require no degradation of a state’s highest-quality waters unless it is economically and socially necessary. (FWS)

This case challenges the U.S. Environmental Protection Agency’s approval of weak Idaho state water pollution rules that don’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.

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 (CWA). But Idaho’s new rules fail to do this, even though the EPA gave its blessing to them.

The CWA 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 CWA 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 CWA allows.

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