Tuesday, July 9, 2019

Water Science Institute Report Finds Legacy Sediment Floodplain Restoration Extremely Cost, Land Efficient

On July 8, the Water Science Institute released its report “Cost Effectiveness of Legacy Sediment Mitigation at Big Spring Run in Comparison to Other Best Management Practices in the Chesapeake Bay Watershed” which examines the cost benefits and land use efficiency of selected environmental BMP’s widely utilized in Lancaster County, Pennsylvania. 
The report, authored by Patrick Fleming, Associate Professor of Economics and Public Policy at Franklin and Marshall College, was commissioned as part of a larger WSI program to evaluate Legacy Sediment restoration opportunities in the lower Susquehanna River watershed.
The cost effectiveness analysis evaluated commonly prescribed low-cost BMP’s including forest and grass riparian buffers, cover crops and non-LS wetland restoration compared to the reduction benefits achieved at the Big Spring Run experiment site in West Lampeter Township, Pennsylvania. 
[Note: The Big Spring Run Project was done under the auspices of the PA Environmental Council to help establish Chesapeake Bay protocols for defining reductions in pollutant loads through individual floodplain restoration projects. The project was designed and completed by LandStudies, Inc.]
The report concludes that LS mitigation is a highly cost-effective method of pollutant abatement, particularly for sediment and phosphorus while cover crops were found to be the most cost effective practice for the reduction of nitrogen.  
LS mitigation was found to reduce sediment loading rates on a per unit cost basis of $.03 per pound or 5 to 21 percent of the cost of other commonly considered BMP’s. Phosphorus reduction costs for LS mitigation were approximately $18 per pound or 1 to 6 percent of the other compared BMPs. 
The analysis found that the cost-effectiveness of LS mitigation remained true under different agricultural land uses and geographic regions in the Chesapeake Bay Program Phase 6 water quality model as well as at different discount rates to convert practice costs in annual terms.  
LS mitigation was found to be cost competitive in per pound N reduction, but certain other practices are modeled to reduce N loads at slightly lower average costs.  
Cover crop per pound N reductions were $4.58 to $7.98 while LS mitigation was calculated at $13.27 to $14.80 per pound under average agricultural land uses in the Chesapeake Bay watershed.
The author noted that “Under various modeling scenarios, the cost-effectiveness of LS mitigation is consistently driven by the very high load reductions available in LS ‘hot spots” such as the BSR study site.” 
 “Hot spots” are high load areas defined and identified in Lancaster by WSI scientists and research associates using advanced mapping and modeling techniques developed for the program.  
The report also reviewed the land efficiency of various BMPs to achieve the same reductions and found that similar reductions of sediment to match the reductions at BSR would require 497-498 acres of forest or riparian buffer.
This report was funded by a USDA Natural Resource Conservation Service Conservation Innovation Grant award with matching support from the Steinman Foundation of Lancaster County.  
The Soil and Water Conservation Society Journal has published an article in its current edition on the applications of this analysis to the Mill Creek watershed in Lancaster County, Pennsylvania.
Click Here for a copy of the report.   Click Here for an overview of the Big Spring Run Floodplain Restoration Project.
For more information on programs and initiatives, visit the Water Science Institute website.
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