USGS Goes with the Flow


Whooosh!  Do you think that your favorite local river is flowing as free as can be?  Sorry to be the bearer of bad river news, but it probably is not, according to the U.S. Geological Survey (USGS).  Apparently 86% of rivers and streams that were assessed by USGS have significantly altered flows.  86%!!  That’s… almost all of them!  Yikes!

In a recent study (PDF), the USGS took a look at the frequency of stream flow alterations that have resulted from land and water management. They also examined the significant impact of these modifications on aquatic organisms, and the importance of flow to sustain and restore the health of the Nation’s streams and ecosystems. 

Researchers found that specific flow conditions can even impact water quality, recreational opportunities, and the maintenance of sport fish populations. So if you care about clean drinking water, or you like to pretend you are wrangling in a great white shark that looks a lot like a trout, you should pay attention to flow! In fact, those native “great white” trout require fast-flowing streams with gravel bottoms, but in cases where streams have severely diminished flow these fish are replaced by less desirable non-native species, such as carp. Oh carp!

Why would we disrupt the natural flow of a river?  Well, that is a complicated question.  Often water demand from many different sources (such as irrigation, flood mitigation, drinking water, recreation, energy production, and development) leads to the depletion of water or installation of dams. Maintaining suitable water flow and habitat for fish and other aquatic life is critical. In particular, high flows are needed to replenish floodplains and flush out sediment that can degrade habitat.

Understanding how stream flow influences the river ecology is important to help diminish impacts caused by the ever increasing demand for water across the country. Of course, in order to lessen water demand, we need to use our water more efficiently and consider the impact that increasing withdrawals will have on the flow of a particular river system. The smaller the stream, the more immediate the impact! 

More information from USGS on this study and other water resource issues across the nation is available on their website

Of course, American Rivers has a water supply program as well.  If you would like to read more about what we are doing to support natural river flows and water use efficiency, visit our Water Supply page!