The Trump Administration has taken aim at the Clean Water Rule, which is a regulation designed to prevent the direct and purposeful contamination of small waterways and wetlands not covered by the Clean Water Act. This regulation was meant to supplement the Clean Water Act, which protects only navigable waters. It was perhaps an oversight in drafting the Clean Water Act that it did not recognize that larger streams are fed by smaller, headwater streams—what we call tributaries or first-order streams. Water that reaches the ocean in large rivers begins its journey in these tributaries and seasonal watercourses in the mountains and uplands.
The Clean Water Rule is also designed to protect the wetlands that line the shore of major waterways. These are often important for the removal of water pollution and as wildlife habitat. For example, much of the nitrate that is carried as a pollutant in stream water can be removed when those waters flush through streamside (riparian) wetlands, where denitrifying bacteria convert nitrate into nitrogen gas.
In New York State, it is illegal for me to “straight-pipe” my sewage into the Hudson River. It is also illegal to dump toxic industrial pollutants, such as PCBs and chromium into the River. Recognizing that the Hudson River is navigable, these contaminants are regulated by the Clean Water Act. The regulations of the Clean Water Rule would extend such protection to seasonal waterways and wetlands that drain into the Hudson River. For the purposes of maintaining water quality in the Hudson River, it shouldn’t matter if I dump my sewage or industrial waste into a small tributary or directly into the River.
The Clean Water Rule also applies to highly seasonal watercourses in the desert Southwest, where one would not want to dump contamination during the dry season, only to see it wash away with the next rainfall. Over the years, we’ve learned this the hard way, when toxic mine tailings have been allowed to spread into waterways.
Importantly, so as not to burden farmers, the Clean Water Rule does not apply to roadside and irrigation ditches and newly constructed waterways.
The Clean Water Rule, informed by the field research of hundreds of wetland scientists, says that tributaries, seasonal watercourses, and wetlands matter. We should protect them.
Doyle, M. W. and E.S. Bernhardt. 2011. What is a stream? Environmental Science and Technology 45: 354-359.
Environmental Protection Agency. 2015. Connectivity of Streams and Wetlands to Downstream Waters: A Review and Synthesis of the Scientific Evidence. https://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=296414&CFID=57703684&CFTOKEN=41807459
Citizen Scientist: http://blogs.nicholas.duke.edu/citizenscientist/what-makes-a-healthy-stream/
 Also known as Waters of the United States; Clean Water Rule: Definition of ‘Waters of the United States,’ 80 Fed. Reg. 37054 (June 29, 2015),