By Tom Daniels, Professor

Department of City and Regional Planning

Weitzman School of Design

University of Pennsylvania

March 19, 2020

The hardest part of creating a successful stormwater management program is to get private landowners to green up their properties. But Prince George’s County, a suburban area with 900,000 residents, just east of Washington, DC, has been making good progress, thanks to innovative financing, willing property owners, local green infrastructure businesses, and a partnership with a Rhode Island-based company, Corvias Group LLC. 

The County covers about 500 square miles and has the second-highest population among Maryland counties. Prince George’s County is served mainly by municipal storm sewer systems (MS4s). The Anacostia River, which has a long history of impaired water quality, marks the western boundary of Prince George’s County and feeds into the Potomac River and the Chesapeake Bay.

In 2010, the US Environmental Protection Agency (EPA) set a Total Maximum Daily Load (TMDL) pollution diet for nitrogen, phosphorus, and sediment for all states within the Chesapeake Watershed and the District of Columbia with a 2025 deadline. In 2012, Prince George’s County adopted a Watershed Improvement Plan as part of the effort to raise the water quality of the Chesapeake. The plan features the design, installation, maintenance, and monitoring of stormwater management projects that will green up 4,000 acres of urban impervious surfaces over the next 30 years.

In 2013, the County created a stormwater utility fee, known as the Clean Water Act Fee, which was expected to produce $1.2 billion over 13 years to fund the greening up of impervious surfaces. The fee is based on three factors: a) the zoning of the property; b) the amount of impervious surface; and c) a flat per property fee. Property owners pay the stormwater utility fee as part of their property tax bill. They can reduce the fee by installing approved stormwater management devices and implementing best management practices. Prince George’s County offers Rain Check rebates for the installation of a variety of stormwater management projects, including: 1) cisterns; 2) green roofs; 3) pavement removal; 4) permeable pavement; 5) rain barrels; 6) rain gardens; and 7) urban tree canopy.

The county’s 2014 NPDES MS4 permit required more stringent stormwater management and consistency with the Chesapeake Bay TMDLs. In response, the County produced a storm water management design manual for property owners and green infrastructure businesses to follow.

Figure 1. Traditional Private Infrastructure Investment vs. a Public-Private Partnership Model. Source: Clean Water Partnership Program Goals. Corvias and Prince George’s County.

A Community-Based Public-Private Partnership

Prince George’s County and Corvias Public Private Partnership entered into a 30-year Clean Water Partnership in 2015. The county initially authorized $100 million to pay for the green infrastructure projects and Corvias’s management fee. The partnership adds to the County’s traditional capital improvements program approach to enable faster installation of best management practices, with a lower cost, and a greater likelihood of achieving the goal of greening up 4,000 acres of impervious surfaces. Figure 1 shows the difference between the traditional capital improvements program approach financed by public dollars and the community-based public-private partnership that relies on private funding.

The Clean Water Partnership, with Corvias as the coordinating manager, operates three programs: Community Outreach for education, Contractor Development to assist existing and new businesses in the procurement and installation and maintenance of green infrastructure (trees, plants, sod, and pervious pavement), and Compliance Programs to ensure that the green infrastructure is performing as required. In sum, the partnership aims to green up impervious surfaces while stimulating local economic development and jobs, especially among local and minority-owned businesses.

By the end of 2019, the Clean Water Partnership had installed 131 green infrastructure projects on 2,237 acres, more than meeting its initial goal of 2,000 acres.  In addition, more than 84% of the work was performed by local minority and targeted disadvantaged subcontractor businesses in Prince George’s County. A total of $132.2 million had been spent on the program, with $112 million going to local and minority businesses. On the cost side, the county saved more than 40% compared to the traditional capital improvements program approach.

Reducing Chesapeake Watershed Pollution

Figure 2. Walker Mill Middle School Micro-bioretention and Swale. Source: The Drop January 2020, p. 6. Credit: Patrick O’Connor Photography.

In its first three years, the Clean Water Partnership projects had decreased nitrogen loading by 32,614 pounds, lowered phosphorus by 3,269 pounds, and cut back sediment by 1,834,791 pounds a year. The County is expected to achieve its goal of 4,000 greened up acres within six years, which will further reduce pollutant loadings.


Prince George’s County has forged a successful public-private partnership with the Corvias Group to: 1) educate property owners about stormwater management options; 2) work with property owners to help finance the installation of green infrastructure projects through the Rain Check Rebate program; and 3) spur the creation of green jobs and support local businesses that design, install, and maintain green infrastructure to manage stormwater. Said Adam Ortiz, Director of the County’s Department of the Environment, “This wasn’t just about meeting a mandate and this wasn’t just about stormwater. This was about community development. So we tried to engineer this program to be an economic driver, to help build a new industry in Prince George’s County that can be used everywhere” (Clean Water Partnership 3rd Year Progress Report, p. 53).

In its first three years, the Clean Water Partnership has greened up more than the goal of 2,000 acres and at a substantial cost savings compared to a traditional public capital improvement program approach. In addition, a large majority of the green infrastructure work has gone to local businesses. In sum, the Clean Water Partnership is a model program of how to green up the impervious surfaces on the private property of current landowners.



Corvias and Prince George’s County. 2018. Clean Water Partnership Progress Report Year 3. Upper Marlboro, MD: Prince George’s County.

Prince George’s County and Corvias. 2016. Using a Community-Based Public-Private Partnership Business Model to Meet Regulatory Stormwater Management Requirements. Upper Marlboro, MD: Prince George’s County.

Prince George’s County and Corvias. 2020. The Drop, January 2020 Newsletter.


Tom Daniels is a professor in the Department of City and Regional Planning at the University of Pennsylvania where he directs the concentration in Land Use Planning and Environmental Planning. He is the author of The Environmental Planning Handbook and When City and Country Collide: Managing Growth in the Metropolitan Fringe and co-author of five other books. He first learned about the Corvias-Prince George’s County partnership while working on a grant from the EPA about stormwater management.