A new study shows less pollution in most New Jersey streams over the last four decades, but cautions that salt levels are rising in some places.
The study by the U.S. Geological Survey says the higher salt levels are probably due to the increasing use of road salt washing into waterways.
It found that levels of two key pollutants, nitrogen and phosphorus, either declined or stayed about the same at most of the 28 streams that were surveyed.
High levels can cause algae blooms and problems with drinking water. They also can cause low levels of dissolved oxygen in water, which harms marine life.
Tim Dillingham, executive director of the American Littoral Society, says water quality in places near heavy development tends to be worse than that elsewhere.