The Clean Water Act (CWA) is intended to support the availability of safe water for all by making it illegal to dispose of pollution into streams. For historical reasons, the CWA is structured around “navigable waters” like rivers, but clearly anything that gets into a tributary or even the soils around streams can influence water quality. Where else would this pollution go?
Consequently, a source of concern and source of confusion has been what happens in non-naviigable headwaters, the small tributaries feeding into streams and rivers, and even ditches, themselves often recommissioned streams. The Clean Water Rule offers some specific guidance to what is included within the CWA. It stipulates that for a stream to be included, it needs to have moving water more than just during a rainfall event, and must show some sort of physical features indicating flowing water. This might be a streambed or bank or some other indication of high water. And then there is the issue of nearby waters, such as wetlands which are not obviously connected to a stream. The limit for those protections is 1500 feet. Ditches not replacing streams are not covered.
These types of clarification are beneficial because they will dramatically reduce the uncertainties of application that crop up when deciding whether the CWA applies. Environmentalists concerned about losses and water quality have gained clarity regarding protection of waterways that feed into navigable waters, and the agricultural industry knows more clearly what its limits are as well. It is important to note that there are a variety of exemptions for agricultural practices already within the Clean Water Act, and these are not altered.
Here are a couple of posts elsewhere on the topic:
1) from the EPA
2) from Healthy Lakes Healthy Lives