TMDL Development—Thumb Run

Case Study Under:  Policy & Planning Solutions         Location:  Virginia
The Case Study

TMDL Development for Thumb Run

The Situation

The Virginia Department of Environmental Quality listed a 7.41 mile segment of Thumb Run as being an impaired water due to the presence of these high fecal coliform counts.  The overall goal of this project was to develop a plan to restore the water quality in Thumb Run such that it is no longer listed as an impaired water in Virginia’s 303(d) Priority List.

The Solution

Under contract to the Rappahannock Rapidan Regional Commission (RRRC), GKY performed data collection, water quality monitoring, non-point source loading analysis, preliminary BMP project targeting, stakeholder involvement activities, BASINS/HSPF modeling, TMDL development, refined BMP project targeting and implementation planning.   GKY developed a watershed model (using BASINS) calibrated to available monitoring data.  Based on the modeling results, we developed an EPA-approved TMDL for fecal coliform for the impaired portion of Thumb Run.  The resulting TMDL will be used as a guide for refining target areas for future BMP implementation in the watershed.  Stakeholders were involved at appropriate points in the process to facilitate successful development of the TMDL.