Human development leads to a decline in stream health

Streams across the United States are suffering a decline in health, as human development alters stream flow and pushes pollutants into the water.

Between 1993 and 2005, scientists with the U.S. Geological Survey (USGS) sampled the algal, macroinvertebrate and fish communities in thousands of streams across the nation. According to a report released by the USGS National Water-Quality Assessment Program, the health of at least one of these three aquatic communities was altered in 83 percent of the streams assessed.

Healthy streams are critical to our communities. Streams provide drinking water, control floods, support commercial and recreational fisheries, and bring aesthetic value into our lives. But stream flow that is altered by human activities can impact native fish, and excess pollutants can alter plant and animal communities.

According to the USGS, tens of thousands of dams and diversions have contributed to the modification in stream flow of 86 percent of the waters assessed in this study. Excess nutrients have altered algal communities, while excess pesticides have had an adverse affect on macroinvertebrates, many of which can be harmed by the toxins found in insecticides.

But one in five streams in urban and agricultural areas was found to be in good health. This finding suggests that green development, on-farm conservation and other best management practices can help us maintain healthy streams alongside continued development.

Read more about the The Quality of Our Nation’s Waters.