Condition of the Watershed
The Little Hunting Creek Watershed was developed during a time when stormwater was treated by piping it off roads and yards and into the nearest stream as quickly as possible. For decades, Little Hunting Creek and its tributaries have functioned as giant storm sewers, and were damaged as a result.
About 92% of the watershed is developed, and 25% is covered by impervious surfaces, such as parking lots, roads, driveways, and roofs. During rain storms, such surfaces produce large volumes of runoff at high velocity that damage streams. To halt and reverse the damage, both the amount and velocity of stormwater runoff must be reduced.
Assessments conducted by Fairfax County and the Commonwealth of Virginia over the past 30 years have found streams in the Little Hunting Creek Watershed in poor condition.
Streambank erosion and sedimentation
Stormwater runoff resulted in an actively widening stream bed and unstable banks in the upper reaches of Little Hunting Creek and its tributaries.
Head cuts (highly eroded stream banks—see picture at right) are created by high volumes and velocities of stormwater runoff.
Sediment is carried downstream, and about 50% to 60% of the bottom of streams in the watershed is affected by sediment deposits.
Riparian (streamside) buffer loss
Over half the stream buffers in the watershed are deficient because they are too narrow, lack vegetation, paved, or covered with lawn.
Poor water quality
The 2005 Little Hunting Creek Watershed Management Plan found poor water quality in the creek due to:
Nutrient-enriched water—it contains too much nitrogen and phosphorus—and aquatic life is threatened by excessive algae in the tidal waters of Little Hunting Creek.
High levels of fecal coliform.
Low dissolved oxygen in the North Branch—at the minimum level needed to support aquatic life.
High levels of polychlorinated biphenyls (PCBs) in the tissues of fish taken from the creek, leading the Virginia Department of Health to issue a health advisory for fish consumed from the creek.
Chlordane in sediment samples from the tidal portion of Little Hunting Creek, above the level that threatens aquatic life.
Low biological health
As of 2005, stream habitat quality was rated as poor or very poor for 73% of the length of streams in the watershed, and fair for 27%. None of the streams had any portion rated as good or excellent.
Macroinvertebrate assessment ranking was very poor. Diversity was low and only pollution-tolerant species lived in the streams of the watershed.
Number of fish species in upstream sampling sites was moderate.
Sources
For more information about the condition of the watershed, see
The Little Hunting Creek Watershed Management Plan.