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Evan Branosky

How a Stormwater-Agriculture Nexus Provides Environmental, Social and Financial Benefits

On August 27, Conservation Innovation Fund announced approval of Kennett Township’s municipal stormwater compliance strategy by the Pennsylvania Department of Environmental Protection (DEP). Approval results from several years of work by Conservation Innovation Fund, Kennett Township, AECOM (the Township’s engineering consultant) and others to achieve requirements of the Commonwealth’s municipal stormwater permit and ensure progress toward improving water quality in the Brandywine and Red Clay Creeks in the Delaware River Watershed.


Why is DEP’s approval so important? Because Kennett Township’s compliance strategy is a two sector solution. It leverages the stormwater and agriculture sectors to improve water quality at a lower cost. Traditionally, legal and financial barriers have made such collaboration difficult. However, when those barriers are overcome, stakeholders can realize significant triple bottom-line environmental, social and financial benefits. 


Two Pollutant Sectors


The division of pollutant sectors is rooted in the Clean Water Act. Section 402 establishes the National Pollutant Discharge Elimination System (NPDES), which regulates the “point source” discharge of pollutants. Section 502(14) defines “point source” to include “... any discernible, confined and discrete conveyance.” In 1990 and 1999, the U.S. Environmental Protection Agency (EPA) required certain municipalities to obtain NPDES coverage for their municipal stormwater discharges. Thus, EPA’s approach regulates municipal stormwater runoff as a point source.


Notably, the Clean Water Act does not define “nonpoint source.” EPA’s website states that nonpoint sources are simply “... any source of water pollution that does not meet the legal definition of ‘point source’ in Section 502(14) of the Clean Water Act.” Thus, by omission, diffuse sources of runoff from intensive agriculture may be considered nonpoint sources.


Leveraging Sectors to Improve Water Quality


The NPDES program encompasses about 7,500 municipalities as census-defined Municipal Separate Storm Sewer Systems (MS4s). These MS4 municipalities are covered under individual or general permits that are developed and issued by delegated permitting authorities (states, other jurisdictions) or EPA. Municipalities weigh many considerations when establishing and determining their compliance strategies, including geographic locations for installing stormwater control measures (SCMs), ancillary municipal goals (combined sewer management, resiliency, employment) and, arguably most important, cost.


Traditionally, compliance strategies have focused on a limited set of actions and SCMs. To demonstrate progress in reducing pollutants from stormwater runoff, for example, MS4 municipalities could conduct urban nutrient management, install vegetated channels in urban locations, install urban infiltration or filtering practices, install wet ponds and/or dry extension basins, or install other SCMs that are demonstrated to remove pollutants of concern. These approaches are critically-important for urban wet weather management and to achieve water quality standards.


However, in certain contexts, agricultural best management practices (BMPs) could extend the options available to MS4 municipalities. For example, a municipality could desire to install bioretention to reduce the sediment and phosphorus delivery that impairs its local waterbody. Perhaps, the municipality only has legal authority to install such practices on public land. But if public land is unavailable in the watershed, and private, working agricultural land plentiful, agricultural BMPs such as cover crops could provide an alternative option to reduce significant loads of sediment and phosphorus. There are dozens of other examples where agricultural or conservation BMPs could provide geographic flexibility for land-constrained municipalities.


In addition to flexibility for siting practices, several studies conclude that agricultural BMPs are more cost-effective at reducing pollutants compared to traditional SCMs. In 2021, for example, Price et al. reviewed project data from counties regulated under the Maryland MS4 program and Maryland Agricultural Cost Share Program. For agricultural BMPs, median costs were $16 per pound total nitrogen (TN) and $489 per pound total phosphorus (TP). These values compared to $1,558 per pound TN and $9,639 per pound TP for SCMs. In 2012, the Chesapeake Bay Commission found even greater cost differences. Their estimated costs for TP reductions from agricultural BMPs ranged from approximately $375 to $1,700 per pound while costs for SCMs ranged from $9,000 to $95,000 per pound.


With such significant cost differences among sectors, impact finance funds like Conservation Innovation Fund are well positioned to generate returns-on-investment. The regulatory driver of NPDES permits establishes demand for pollutant reductions. Cost differences provide a sales opportunity. Conservation Innovation Fund structures investments to generate returns that pay for agricultural BMPs, provide incentive payments, and thus additional income, to farm participants, and additional revenue on transactions to offset overhead costs.


Triple Bottom-Line Benefits 


The environmental, social and financial benefits of stormwater-agriculture partnerships are clearly demonstrated by Conservation Innovation Fund’s project for Kennett Township.


  • Environmental: DEP requires Kennett Township to reduce its phosphorus load to Brandywine Creek by 7.83 pounds during a five-year permit term. Conservation Innovation Fund’s project reduces 9.38 pounds, which is 120% of the required reduction amount.

  • Social: When developing its compliance strategy, Kennett Township determined that Conservation Innovation Fund’s project provided the quickest option for achieving required load reductions and avoided construction and transportation impacts on residents.

  • Financial: Kennett Township considered an alternative compliance option, which included retrofits of three stormwater basins. These projects would have required additional site study, engineering and owner permissions. Conservation Innovation Fund’s project provided a four-times lower cost to the municipality, compared to the alternative path.


Currently, Conservation Innovation Fund is working in Pennsylvania and neighboring states to realize these benefits for additional municipalities, farms and residents. If you are interested in working with us, please contact me, Evan Branosky, Managing Director of Conservation Innovation Fund, for more information at ebranosky@conservationinnovationfund.org.  


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