Spillover Leads to Another Gunpowder River Flood: From Unfishable to Unfathomable

To say that the river is unfishable at these levels is a gross understatement. It’s dangerous, and not just for anyone trying to fish this holiday weekend. Anyone planning on using the river responsibly, (kayakers included) should give it a few days to settle down. Tuesday the Gunpowder River was flowing at a gauge height of 2.35 FT and 203 CFS. Today, the river peaked at 7.2 FT and 1, 690 CFS. The United States Geological Survey, (USGS) measures the Gunpowder River in feet and flow at the Falls Rd gauging station in Parkton, MD.
Gunpowder River in Flood Expressed in Gauge Height in Feet
The top hydrograph shows the dramatic, sudden and dangerous effect that rainfall has on the Gunpowder River when Prettyboy Reservoir is managed by Baltimore City at full pool, (during hurricane season no less) and spillover occurs. The rise in river levels on the top graph is expressed in feet.

Floods caused by spillover are disruptive not only for any recreational users interested in spending a day afield but for the wild fish in this nationally recognized tailwater fishery that have been clearing redds in earnest to spawn the next generation.

At first glance, during a flood of this magnitude, the river is full of water and mud. Upon closer inspection, the spillover and accompanying high flows that cause dangerous river levels upstream in Gunpowder State Park accelerate erosion by undercutting and destabilizing banks and effect the degradation of downstream waters.

The concurrent sediment loading into Loch Raven Reservoir, ignores the 2006 Environmental Protection Agency Total Maximum Daily Load, (TMDL) for Phosphorous and Sediment in Loch Raven. TMDL’s are described in the document as;

A TMDL reflects the total pollutant loading of the impairing substance a waterbody can receive and still meet water quality standards. TMDLs are established to achieve and maintain water quality standards. A water quality standard is the combination of a designated use for a particular body of water and the water quality criteria designed to protect that use. Designated uses include activities such as swimming, drinking water supply…

As it relates to water supply designations, Loch Raven reservoir delivers drinking water to approximately 1.5 million Baltimore metro area residents. However, the protocol that allows severe flooding via spillover not only has the potential to degrade downstream waters but is also counter to The Reservoir Watershed Management Agreement of 2005, Which states in part, under Program Goals that;

The broadest and most fundamental goal of the Reservoir Program is to ensure that the three reservoirs and their respective watersheds will continue to serve as: (a) Sources of high-quality raw water for the Baltimore metropolitan water-supply system; and (b) Areas where the surface waters will continue to support existing environmental, wildlife-habitat, and aesthetic purposes, as well as beneficial recreational uses.

The rise in river levels on the bottom graph is expressed in CFS, (cubic feet per second). For perspective, triangles in the lower quadrant of the graph express daily median flows calculated over the past ten years. Today’s triangle represents a median flow of 49 CFS.
Gunpowder River in Flood Expressed in CFS
The agreement Penned by then Mayor, now Governor, Martin O’Malley and the City Council of Baltimore; Baltimore County, Carroll County; the Maryland Department of the Environment, the Maryland Department of Agriculture; the Baltimore County Soil Conservation District and the Carroll Soil Conservation District; the Reservoir Watershed Protection Committee; and the Baltimore Metropolitan Council is being ignored to the detriment of the river, its biological communities, recreational users and the residents of the Baltimore City Metro Area which depend on the Gunpowder River for their daily drinking water needs. If you’re still reading and are interested in this matter please contact us via email keeper@gunpowderriverkeeper.org

Related post: Prettyboy Spillover leads to Gunpowder River Flooding Mayhem