In December 2014 the City of Baltimore released an ambitious management plan for reducing stormwater pollution from nearly 24,000 acres of pavement within City limits. Nitrogen, phosphorous, and sediments contained in this stormwater are responsible for recurring hypoxic “dead zones” in the Chesapeake Bay devoid of fish, crabs, and other aquatic life. Stormwater runoff from cites accounts for 10-20% of the load of these pollutants entering the Bay. Although efforts to control pollution from other sources are beginning to pay off, pollution from urban runoff is still growing. Baltimore’s Stormwater Management Plan (SMP) will play a role in reversing this trend.
The SMP was created to meet Baltimore’s obligations under the Clean Water Act and is based on implementation of a variety of best management practices (BMPs) designed to reduce runoff and filter out pollutants from at least 4,240 acres of paved surfaces. Major BMPs will include expanded mechanical street sweeping, stream restoration, bioretention ponds, artificial wetlands, and converting impervious pavement to open space and forest.
Many, including Maryland’s new Governor Larry Hogan (R) have expressed concerns over the costs jurisdictions like Baltimore will face implementing their SMPs and over the stormwater fees collected to pay for them. But from an economics standpoint, the point is not how much it costs but whether or not the benefits generated by these SMPs exceed costs and how they can be configured to maximize such benefits. CSE’s preliminary analysis of Baltimore’s SMP tackles these questions by using Baltimore’s Genuine Progress Indicator (GPI) as a framework. The results are encouraging. In particular, our analysis found that:
- The SMP has the potential to generate nearly $20 million in economic benefits each year with no special emphasis on GPI-enhancing design features. Major annual benefit categories include those related to ecosystem services of streams, wetlands, parks and open space as well as volunteering, employment, and water quality.
- If GPI-enhancing design features were added – features like local hiring preference, greater emphasis on green infrastructure, and location of BMPs in residential areas – then the SMP’s annual economic contribution would rise by 29% to over $25 million per year.
- Over a 20-year period, the SMP as currently configured is likely to generate over $22 million in net benefits with a benefit-cost ratio of 1.08 and a social return on investment of over 8%.
- With GPI-enhancing features added, net benefits could be substantially larger. Our analysis shows that 20-year net benefits could be over $107 million with a benefit-cost ratio of 1.40 and social a return on investment of nearly 40%. This underscores the importance of paying attention to design features of the SMP as it is implemented on the ground and recognizing that some design features will pay off far better from a social, economic, and environmental perspective than others.
As more precise economic data on both costs and benefits of projects and programs to implement the SMP become available, CSE’s preliminary analysis can also be refined and updated. So too can the list of GPI-enhancing measures. Doing so will help decision makers implementing the SMP to choose options that maximize its social and economic returns – an important goal recognized by the Environmental Protection Agency in its new Integrated Municipal Stormwater and Wastewater Planning Approach Framework, adopted last summer. That framework recognizes that communities can “manage stormwater as a resource, and support other economic benefits and quality of life attributes that enhance the vitality of communities.” As shown in CSE’s preliminary analysis, the GPI provides a useful analytical tool for achieving this goal.