Study: Browner Water Might Be Good Sign

A study suggested a color change in some lakes and streams in Britain, eastern North American and southern Scandinavia might be a good sign.

For 20 years, some waterways have been increasingly stained brown and now scientists led by University College London and the U.S. Environmental Protection Agency have determined the change is indicative of a return to a more natural, preindustrial state following a decline in acid rainfall.

There have been numerous attempts to explain what’s happening, with everything from global warming to changing land-use cited as the cause, said Don Monteith, a University College London senior researcher. Some studies have suggested we’re seeing an unprecedented phenomenon as soils destabilize with unpredictable consequences for the global carbon cycle.

But John Stoddard of the EPA said: “By analyzing water chemistry records from over 500 sites across the northern hemisphere we’ve found the dominant factor in the whole process is not global warming. The most important driver has actually been the major reduction in acid rain since the 1970s.

In some ways we’re seeing waters returning to their natural, preindustrial state, said Stoddard. However, more research is needed into the implications for freshwaters.

The study appears in the journal Nature.