Water temperatures are increasing in streams and rivers around the country and that is having a huge impact on the dependent ecosystems, according to new research from ecologists and hydrologists from the University of Maryland and elsewhere.  

The research, published in the journal Frontiers in Ecology and the Environment, documents the statistically significant long-term rise in 20 major U.S. streams and rivers, including the Potomac in Maryland and others such as  the Colorado, Delaware and Hudson.

The annual mean rise was .02-.14°F a year. The water temperature increases also correlated to air temperature increases. And increases were more rapid in urban areas. There was a 3°F increase since 1939 in the Patuxent River, said David Secor of the University of Maryland Center for Environmental Science's Chesapeake Biological Laboratory.

“Warming waters can impact the basic ecological processes taking place in our nation’s rivers and streams,” said Sujay Kaushal of the University of Maryland Center for Environmental Science and lead author of the study. “Long-term temperature increases can impact aquatic biodiversity, biological productivity, and the cycling of contaminants through the ecosystem.”

The researchers believe development and global warming are a "one-two punch" particularly in the urban areas and are having a huge impact on ecosystem health. In the city there are "urban heat island effects” from all the buildings, roads, concrete and asphalt. 

The waterways could be helped by conserving riparian forests, reducing impervious surfaces, adopting “green” infrastructure practices and reducing greenhouse gas emissions, they researchers said.

Associated Press photo of the Potomac River