Experimental Agricultural Stormwater Management System Yields Promising Results

While stormwater runoff management is primarily perceived as an urban issue, Maryland’s agricultural community also faces stormwater management requirements under the Chesapeake Bay Total Maximum Daily Load.  A July 2 Star Democrat article reported on the recent and favorable findings regarding an experimental agricultural stormwater management system.

After implementing an agricultural stormwater cascading system on his farm near Chestertown in 2011, new data shows that Samuel Owings’s self-constructed system is fulfilling its purpose to reduce agricultural runoff from flowing into the Hambleton Creek, Chester River and Chesapeake Bay.  …

The cascading system is a series of four basins that are between 35 to 45 feet wide and 120 to 170 feet long. Using grass seed, starter fertilizer, curlex and natural vegetation, the system is placed in a grass waterway and drainage ditch and begins at higher elevations and moves toward lower elevations with the last basin placed at the edge of an existing wetland and pond.

With the assistance of grant funding, University of Maryland graduate student and research assistant Rosie Myers completed half of a two-year analysis of the effectiveness of Owings cascading system.  Myers derived her conclusions based on collected data from nine storm events (about 1/3 of last year’s storm events for the Queen Anne’s County region where Owings’ farm is located).

Looking at all nine storm events, Myers said 64 percent of the water that entered the system did not leave, and cited an 11 percent reduction in nitrogen and a 5 percent reduction in phosphorus. She then excluded the two largest storm events from her data, and the system showed over a 95 percent efficiency rate, which she attributed to the large washouts re-suspending and discharging sediment and nutrients captured from earlier storms.

“If it can reduce the washouts from the basins, this can be a very efficient system,” Myers said.  …

The cascading system brings many benefits to agricultural environments, Owings said, as it uses little or no tillable land; traps and filters sediment, nitrogen and phosphorus; provides instant gratification; uses simplistic materials such as grass seed and starter fertilizer; replenishes groundwater; is easily replicated by other farmers; creates wildlife habitation; creates top soil as a byproduct; and recycles phosphorus by spreading it back on farm fields.