A full Baltimore City Reservoir and a Nor’easter that brought rain to the Hereford Zone last evening through today combined to create a spillover event at Prettyboy Dam. The Gunpowder River flow rose from 75 Cfs to over 1,190 Cfs. Water temperatures also moved up sharply from 56 to 66 F. This photo taken last night shows a full Reservoir while the storm approached the area. With relatively no freeboard (or buffer) at Prettyboy Dam, and heavy localized rainfall, spillover and related severe flooding occurred throughout the Hereford Area of Gunpowder State Park impacting the riparian habitat of the Gunpowder River.
For weeks the River level has been shin deep (at 29 to 31 CFs) through the Park, making it very difficult to float the River without dragging canoes and kayaks over exposed gravel bars. The USGS Hydrograph (read from left to right) illustrates River levels in cubic feet a second (Cfs) at close to median flows (in line with the triangles), low flows (below the triangles), and finally spillover and flooding.
That Baltimore City DPW manages Gunpowder River levels to maintain a full Prettyboy Reservoir during Hurricane Season is troubling. This practice has led to significant flood events in the fall of each of the past three years. (Please see related posts below). Impacts of flooding are at odds with both the Baltimore City Watershed Agreement that promotes “existing environmental, wildlife-habitat, and aesthetic purposes, as well as beneficial recreational uses” and the Loch Raven TMDL (Total Maximum Daily Load) which was established to “achieve and maintain water quality standards including designated uses” and protects the downstream drinking water supply reservoir from sediment and phosphorus pollution.
As with Hurricane Irene, Tropical Storm Lee and Hurricane Sandy, spillover from this Nor’easter is undercutting and de-stablizing river banks, accelerating erosion and reducing the capacity of Loch Raven Reservoir. These flood events are detriment to the river, its biological communities, recreational users and potentially to the residents of the Baltimore City Metro Area which depend on the Gunpowder River for their daily drinking water needs. Interested in this matter? Please contact us via email