DELAWARE RIVER BASIN COMMISSION

Low Flow

Low streamflows were commonplace in the dry summer months of 1999. The impacts of climatic versus anthropological effects on low flows needs to be determined. Probably, primarily the result of the prolonged drought, some streams were further impacted by the loss of former, greater groundwater recharge, the source of flows in springs and seepages. Some areas have diminished low flows due to sewer bypasses. Aquatic communities become stressed. The riparian vegetation that protects the streambanks from erosion are also stressed as the soil moisture usually supplied by the stream is lost. Root zones dry out. The extent to which the riparian vegetation can survive such soil-moisture depletion needs to be investigated.

Stony Brook, east of Interstate Route 80, Knowlton Township, Warren County, NJ. A dry streambed on June 16, 1999

Oughoughton Creek, Lower Mount Bethel, Northampton County, PA.
View upstream beneath lowest downstream bridge, June 16, 1999.

Some streams low flows are enhanced due to manmade manipulations. The Delaware River is enhanced by augmented flow from the New York City reservoirs. Other examples exist in the Basin.

East Branch Perkiomen, Bedminster Township, Bucks County, PA. View looking upstream of the Point Pleasant Diversion near Elephant Road.

View downstream of the Point Pleasant Diversion. Note the significantly increased flow from the diversion. Photographs taken June 30, 1999.

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