Using Conservation Easements as a Water Quality Protection Tool in the Goose Creek Watershed, Northern Virginia

by Hamm, Tracy

Goose Creek was placed on Virginia’s list of impaired waters in 1998 for its failure to attain the standards for both primary contact use and aquatic life use due to fecal coliform and sedimentation, respectively. The Middle Goose Creek Subwatershed is dominated by large parcels and is covered by a mosaic of forest and agriculture. It is also immediately upstream of the rapid development pressures of Loudoun County, Va. One particularly comprehensive tool for encouraging and implementing water quality protection is to place a parcel under conservation easement. The objectives of this project are as follows: (1) develop and utilize a prioritization scheme for targeting parcels to be placed under conservation easements, (2) compare the existing easements with this prioritization, and (3) make management recommendations as to which priority parcels remain to be targeted for easement and which existing easements need to be strengthened.

The prioritization scheme is based on four metrics: runoff potential, buffer potential, forested streambank, and agricultural streambank. The top five highest ranking parcels of each metric were overlaid to produce a total of 14 priority parcels. Despite 43% of the land in this subwatershed already being under conservation easements, only six of the 14 priority parcels were already under easement.

My recommendations are to target priority parcels not yet under conservation easement to be placed under easement and to amend existing easements on priority parcels to strengthen riparian buffer requirements. I suggest first focusing restoration efforts on those “source” parcels identified as having the greatest potential to contribute sediment and fecal coliform bacteria to Goose Creek, then shifting to preserving those “sink” parcels which have the greatest potential to decrease levels of sediment and fecal coliform. I have thus developed a flexible framework for prioritizing a landscape with the goal of maximizing water quality and using conservation easements as the tool to accomplish this protection. This methodology can be used by organizations with limited resources to focus efforts most efficiently.