In time for the hearings by federal agencies this week necessary to begin the Biden administration's amendments to the 2020 Navigable Water Protection Rule or the Dirty Water Rule, a new study highlights how critical non-perennial streams are important to ecosystems and society and how these streams are threatened by climate change.

These non-perennial streams or waterways that don't flow all year round have been examined in a new study published in Environmental Research Letters. Researchers found a widespread decrease in the flows of the streams.

READ NEXT: Interior Department Breathes New Life Into Climate Accountability, Social Justice

Scientists behind the study have warned that "stream intermittency is changing" across the U.S. and that those binary classifications used for the streams - "perennial," "intermittent," and "ephemeral" - as used in policymaking might not be valid since flow dynamics could also change over time.

In 2020, the Trump administration implemented the Navigable Water Protection Rule, informally known as the "Dirty Water Rule," and used these classifications to effectively eliminate clean water protections for more than 60 percent of the bodies of water in the U.S., including streams, rivers, lakes, and wetlands. 

This covers about 90 percent of rivers and streams in the Southwest, a mostly desert region. With the 2020 rule, most of the nation's waterways are left unprotected from pollution and development, especially those that do not flow year-round and those whose flows are declining due to climate change.

"Here in New Mexico 93 percent of the state's streams and rivers are intermittent or ephemeral," explains WildEarth Guardians Rio Grande Campaigner Tricia Snyder. She adds that these temporary waterways are important in arid environments, support plants and wildlife, affects water quality, and charging groundwater supplies. 

With the introduction of the 2020 Dirty Water Rule, these waterways lost federal protection, a condition she calls unacceptable. The new study comes at a critical time as the U.S. Environmental Protection Agency (EPA), and the Army Corps of Engineers are starting to revise the regulatory definition of "waters of the United States" under the Clean Water Act. 

Also, the most recent version of the rule, the 2020 "Navigable Waters Protection Rule," was vacated in a hallmark decision from the U.S. District Court for the District of Arizona.

The litigation was brought forth by environmental nonprofit Earthjustice on behalf of the Pascua Yaqui Tribe, Quinault Indian Nation, the Fond du Lac Band of Lake Superior Chippewa, Tohono O'Odham Nation, Menominee Indian Tribe of Wisconsin, and Bad River Band of Lake Superior Chippewa.

"The Dirty Water Rule was the biggest step backwards in the protection of our nation's waters since the Clean Water Act was made into law in 1972," the WildEarth Guardians campaigner added.

She noted that while they are happy that the Biden administration is working to undo what the Trump administration did, they were disappointed that it still had to go to the courts to put a stop to the misguided ruling that could've harmed communities, cultures, and the environment.

Over the past two weeks, listening sessions were held - involving various nonprofits like WildEarth Guardians, Rio Grande Waterkeeper, and Waterkeeper Alliance, together with other public health and environmental groups and concerned citizens.

Both the EPA and the Army Corps accepted written comments. Interested parties were encouraged to submit their comments at the U.S. Regulations Website.

READ MORE: Texas Officials Prepare Lawsuits Against Joe Biden's Proposals on Immigration, Environment