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The map to
the right shows the location
of the wells and streams used
by the USGS to monitor water
conditions in Maryland, Delaware,
and the District of Columbia.
In May, water levels in streams
and wells were normal except
for two wells and Antietam
Creek in Maryland, and White
Clay Creek in Delaware, which
remain above normal.
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Precipitation
Preliminary rainfall
data from the National Weather Service
shows that rainfall ranged from
below normal at Washington National
Airport (2.98 inches) to above normal
at Baltimore (5.06 inches) across
the region in May. Normal rainfall
for May is about 3.8 inches.
Chesapeake
Bay
Monthly
mean streamflow into the Chesapeake
Bay during May averaged 69.5 bgd
(billion gallons per day), which
is 9 percent above normal. In 2004,
flow to the Bay has been near average.
This is in contrast to May 2003
when flows and the corresponding
amount of nutrients and sediment
were near record high levels.
The
USGS just completed estimates of
nutrient and sediment loads to the
Bay for 2003. The graph to the right
shows that in 2003, more than twice
the amount of river flow (86. 7
billion gallons per day) entered
the Bay than in 2002 (37.7 billion
gallons per day). 
This
was the third highest amount since
1937, when the USGS began keeping
records to compute estimates of
the total flow to the Bay. Nutrient
and sediment loads in 2003 were
influenced by near-record river
flow to the Bay. In 2003, nutrient
and sediment loads to the Chesapeake
Bay from its major rivers were the
second highest since 1990. The increased
nutrient and sediment loads resulted
in less light in Bay waters, which
contributed to a decline of submerged
aquatic vegetation (SAV). The increased
nutrient loads also contributed
to the low dissolved oxygen levels
in the Bay during the summer of
2003.
Loads
from the nine major rivers entering
the Bay in 2003 
were
much higher than in 2002, and contained
about 3 times the amount of nitrogen,
5 times the amount of phosphorous,
and 11 times the amount of sediment
(see graphs below). The loads were
higher due to both the near-record
river flow and an increase in nutrient
and sediment concentrations in the
rivers. The increased nitrogen concentrations
were a result of increased erosion
of sediment and high amounts of
nitrogen being flushed from the
land and streams.
In
2004, flow to the Bay has been near
average—therefore, sediment
and nutrient loads could be less
than in 2003. For more information
on sediment and nutrients loads
entering the Chesapeake Bay in 2002
and 2003, visit: http://chesapeake.usgs.gov/chesbay/featureflowandload.html.
Additional information on the Chesapeake
Bay can be found at: http://chesapeake.usgs.gov.
Streamflow
Streams
in Maryland and Delaware were flowing
at normal levels in May, except
for Antietam Creek in Maryland and
White Clay Creek in Delaware, which
were above normal. Current and historical
streamflow data can be monitored
on the web at: http://waterdata.usgs.gov/.
Five-year monthly streamflow hydrographs
from the USGS stream-gaging network
can be viewed on the USGS website
at http:/md.water.usgs.gov/surfacewater/streamflow/.
Daily
streamflow on the Potomac River
near Washington, D.C. averaged 10.7
bgd in May, which is 13 percent
above normal for the month of May.
More information on the Potomac
River is available at: http://md.water.usgs.gov/monthly/poto.html.
Groundwater-Unconfined
or Shallow Aquifers
Groundwater
levels dropped in most of the wells
used by the USGS to monitor unconfined
or shallow aquifer response to climatic
conditions in the bi-state region.
However, all were in the normal
range during May except for wells
in Baltimore and Washington Counties
in Maryland. Five-year hydrographs
of groundwater levels for the climatic
indicator wells can be viewed at:
http://md.water.usgs.gov/groundwater/.
Groundwater-Confined
or Deep Aquifers
Groundwater-Confined
or Deep Aquifers
Water is plentiful at the surface
(streams, reservoirs, and shallow
groundwater reserves are full),
however some of the water levels
in the deep confined aquifers used
for water supply by many people
living in southern and eastern Maryland
and Delaware continue to decline.
The decline is caused by pumping
at greater rates than the rate at
which deep groundwater is recharged,
and because the confined aquifers
are deep, water levels in confined
aquifers take longer to respond
to climatic conditions than water
levels in shallow aquifers. Confined
aquifer wells can be viewed at http://md.water.usgs.gov/groundwater.
Real-time water-level data collection
can be viewed at: http://waterdata.usgs.gov/md/nwis/gw
Reservoir
Storage
Contents of the
Baltimore reservoir system remained
at 100 percent capacity. Storage
in the Triadelphia and Duckett Reservoirs
on the Patuxent River, which serve
Montgomery and Prince Georges Counties,
has dropped to 98 percent of capacity.
Water
Monitoring
The
USGS has been collecting National
streamflow data for 120 years, since
1884. Regular streamflow monitoring
began in Maryland on the Potomac
River at Point of Rocks, Maryland
in 1895 and continues today. Streamflow
and groundwater levels are used
to assess the current water conditions
and can be used to predict the potential
for flooding and drought conditions.
These USGS data have been provided
to State and local water resource
managers and are critical for making
appropriate decisions on water regulation.
For more information on streamflow
and groundwater levels in Maryland,
Delaware, and the District of Columbia,
visit WaterWatch at: http://md.water.usgs.gov/waterwatch/.
The
real-time streamflow stations used
in this analysis are operated in
cooperation with the Maryland and
Delaware Geological Surveys, the
Maryland State Highway Administration,
the U.S. Army Corps of Engineers,
the Maryland Department of Natural
Resources, the Maryland Department
of the Environment, Baltimore County,
Baltimore City, and other agencies.
The observation wells used in this
analysis are operated in cooperation
with the Maryland and Delaware Geological
Surveys and the Interstate Commission
on the Potomac River Basin. The
real-time wells are operated in
cooperation with the Maryland and
Delaware Geological Surveys, the
Interstate Commission on the Potomac
River Basin, and Calvert County,
Maryland. The USGS publishes data
for 137 streamflow stations and
389 observation wells across Maryland,
Delaware, and the District of Columbia.
USGS
Reports
The
USGS Maryland, Delaware, and D.C.
District publishes reports highlighting
recent scientific work done by this
office. Fact sheets and other publications
are available online from the Publications
section of the District homepage
at: http://md.water.usgs.gov/publications/online.html.
Nitrates
and Pesticides are Common in Delmarva
Peninsula Ground Water and Streams
Many different chemicals
from human sources, including nutrients,
pesticides, and volatile organic
compounds (VOCs), are found in the
shallow ground water and streams
of the Delmarva Peninsula, according
to a recent study by the USGS. With
the exception of nitrate, most of
the chemical concentrations are
below existing water-quality standards,
but many of the chemicals detected
do not have such standards or guidelines.
According
to Judy Denver, USGS hydrologist
in charge of the multi-year water
quality study, “Nitrate in
domestic wells is of concern because,
unlike public-supply wells, most
domestic wells are not monitored
regularly and many homeowners are
unaware of potential water-quality
problems. Drinking water with high
nitrate concentrations can cause
health problems for infants.”
And, as Denver notes, “There
is little information about the
potential additive or synergistic
effect on human health and aquatic
life of low levels of multiple compounds
in streams and drinking water.”
USGS technician Deb Bringman collects
ground-water sample for chemical
analysis. A
news release based on this report
can be accessed at: http://chesapeake.usgs.gov/chesbay/.
The report, "Water Quality
in the Delmarva Peninsula, Delaware,
Maryland, and Virginia, 1999-2001,"
can be accessed on the World Wide
Web at http://water.usgs.gov/nawqa/nawqa_sumr.html.
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