WASHINGTON – Underground sources of potable water for about 40 million people in agricultural areas do not comply with drinking standards,according to a new national study by the U.S. Geological Survey.
The study shows that high concentrations of nitrogen and phosphorus,nutrients that in large amounts could endanger aquatic environments and human health,remained the same or increased in many streams and aquifers since the early 1990s.
“What we found is despite improvement in water quality made by reducing point sources of nutrients,our data show that sources of nutrients have resulted in concentrations of both of nitrogen and phosphorus far above the criteria recommended by the EPA,” said Neil Dubrovsky,USGS hydrologist and lead scientist on the study. Dubrovsky presented the survey's findings Friday in a Senate meeting room.
The study showed a lack of national-scale progress in controlling nutrient sources and movement over the last decade.
According to the study,high concentrations of nutrients are responsible for creating “dead zones,” which are portions of streams where algae grows heavily. When the algae plants decay,they absorb available oxygen,killing aquatic life.
Nutrient pollution remained as one of the top three causes of degradation in U.S. streams and rivers for decades,according to the U.S. Environmental Protection Agency.
Concentration of nitrates in groundwater wells was more significant in agricultural areas and shallow wells than urban zones with public drinking water supplies. In rural communities,one in five shallow private wells contained nitrate levels above the EPA standard for drinking water.
Streams in agricultural areas exceeded nitrate contamination levels in urban streams. This was particularly evident in in the upper Midwest,where use of fertilizers or manure is relatively high.