Compliance with Delaware forest harvest law protects water quality

November 24, 2017

Delaware timber harvests achieved a 93 percent rate of compliance with best management practices designed to protect water quality and limit soil erosion, according to a new report. Recommended practices included: pre-harvest planning to properly locate access roads, avoiding stream crossings and wetlands, curtailing harvests during wet periods, and maintaining sufficient forest buffers near water.

Dr. Anne Hairston-Strang, a forest hydrologist with the Maryland DNR Forest Service, sought to assess the use and effectiveness of BMPs by surveying a total of 72 sites in Maryland and Delaware from 2014 to 2016. Selected sites were locations with waterway crossings and buffers with the greatest potential for water quality impacts. Effects were expected to be larger than normal because high rainfall during the 2014-16 period represented an increase of 20 percent above the 30-year average.

However, final data indicated that the average sediment delivery across all locations was less than one cubic foot per site, indicating that proper use of BMPs was successful at protecting water quality during harvest operations. The results are also important because a substantial part of western Delaware is located in the Chesapeake Bay Watershed, the largest estuary in the United States, and a critical natural resource area targeted for public and private restoration efforts. The report also offers evidence that Delaware's relatively flat coastal plain topography can help make the application of BMPs even more effective at preventing sediment deposits in waterways. Other key study findings are summarized below.

"Protecting water quality and the physical environment are of utmost importance during any forestry operation," said Michael A. Valenti, Delaware state forester. "Timber harvesters work closely with professional foresters to ensure adherence to Delaware's Erosion and Sedimentation Law. Utilizing a comprehensive set of best management practices since 1994, the forest industry has attained a very high level of compliance with this protective law. We are very pleased with these results and our goal, of course, is 100 percent compliance. The Delaware Forest Service will continue to work with operators to correct the few minor violations uncovered during this study in a cooperative effort to protect Delaware's water quality."


Forests are one of the best land uses for achieving high water quality. Trees act as natural filters to mitigate erosion, remove pollutants, reduce stormwater flow, and lower water treatment costs. Forests are also sustainable sources of valuable wood products and good jobs. As part of a comprehensive forest stewardship plan, activities such as pre-commercial thinning can keep forests healthy from overstocking and forest pest issues. Similarly, properly planned and well-managed harvests of working forests can help landowners capture economic benefits while also meeting important resource objectives such as water quality, wildlife, and recreation. Timber income can help owners keep their land as forestland, preventing its conversion to more developed land uses that contain greater impervious surface area with the potential risk of a corresponding decline in water quality. As part of its core programs, the Delaware Forest Service offers free management planning to forest landowners, including cost-share-assistance for activities such as reforestation, as well as property tax exemptions.

Best management practices for forestry operations include:

  • Planning harvests to avoid stream crossings, steep slopes and wetlands
  • Locating roads and skid trails on low slopes (usually less than 15 percent)
  • Timing harvest operations to avoid wet periods
  • Diverting water off roads and skid trails to infiltrate into the forest floor using earthen berm water bars, broad-based dips or other diverters
  • Stabilizing roads, landings and steep skid trails
  • Using bridges, culverts or temporary corduroy logs for water crossings
  • Crossing streams at right angles to minimize disturbance
  • Leaving buffers to shade waterways

Buffers along riparian areas are particularly important, but the buffer requirement need not be overly restrictive to commercial operators: harvesting can occur within the buffer zone but a minimum of 60 square feet of basal area must be left – usually over half of the trees in an area.