Small Watershed Action Plan for Rural Lower Gunpowder Falls

Baltimore County , Maryland

In an effort to meet anticipated NPDES permit requirements for impervious area restoration and Chesapeake Bay TMDL compliance, KCI’s water and natural resources team assisted the Baltimore County Department of Environmental Protection and Sustainability to prepare watershed management plans. These assessments identified problem areas, potential improvements and outlined new treatment options and upgrades. Engineers and scientists completed a comprehensive GIS analysis, characterized the watershed, took field measurements and used a variety of models to analyze pollution loading.

Our team was responsible for work performed for two of the upland assessments: the Hotspot Site Investigation (HSI) and Neighborhood Source Assessment (NSA). Field crews assessed pollution-producing behaviors in commercial and industrial areas for the HSI, and conducted a survey of residential subdivisions to evaluate pollution sources, stewardship behaviors, and restoration opportunities for the NSA. The HSI evaluates six common operations at each potential hotspot: vehicle operations, outdoor materials, waste management, physical plant, turf and landscaping, and stormwater infrastructure. Neighborhood assessments were performed to identify residential behaviors that contribute to stormwater quality problems.

KCI reviewed publicly available deterministic, statistical, and stochastic water quality models that incorporate water temperature simulation and provided a summary for DEPS staff with a recommendation for the model to be used, then used the recommended models for several scenarios, varying parameters such as discharge, shading from forest buffer, upstream impervious area, and upstream forest cover.

Bill Frost, PE, D.WREWatershed Planner

Bill Frost, PE, D.WRE

KCI developed a pollutant load model to assess nutrient and sediment improvements. Existing conditions were analyzed using Chesapeake Bay pollutant loading rates for land uses and BMP pollutant removal efficiencies. The model was used to calculate reductions from the proposed urban and agricultural restoration actions in comparison with TMDL requirements. The rural gunpowder falls watershed included a pilot study to identify sources of temperature pollution within one of the sub-watersheds.