Over the past 10 years, nitrogen concentration trends are
downward at about half (16 out of 33) monitoring sites within
the Bay watershed. The trend results indicate that in many
locations, management actions, such as improved wastewater
treatment and nonpoint-source pollution controls (i.e. urban
stormwater runoff and agricultural runoff controls), have
reduced nitrogen concentrations in streams. In addition, in the
last 5 years, higher yields indicate a tendency to be located in
the northern half of the watershed, conversely. lower yields are
more numerous in the lower half of the watershed. The short-term
flow-adjusted trends and yields indicator is calculated, and
results and maps are published annually by the U.S. Geological
Survey as part of a larger effort to determine loads and trends
in nutrient and sediment concentrations and streamflow in the
Chesapeake Bay watershed. Date created: Mar 10 2011 / Download (
4.32 MB )