In December 2015 United States Senator Sheldon Whitehouse (D – Rhode Island) asked the United States Government Accountability Office (GAO) to research the use of green infrastructure by municipalities to meet Environmental Protection Agency (EPA) stormwater quality permitting requirements. On October 30, 2017 the GAO publicly released a report of their findings. The report:

• Describes the extent to which selected municipalities are incorporating, and funding, green infrastructure in stormwater management efforts.
• Describes what challenges, if any, municipalities reported facing in incorporating green infrastructure into stormwater management efforts.
• Examines efforts EPA is taking to help municipalities use green infrastructure.

GAO obtained information about the first two items using a survey of 20 randomly selected municipalities with stormwater pollutant discharge permits (Table 1) and 11 randomly selected municipalities that have entered into consent decrees with EPA to mitigate combined sewer overflows (CSOs) (Table 2).  Both groups were randomized to include a wide range of sizes and geographic locations.

Table 1 – Surveyed Municipalities with Stormwater Discharge Permits

Table 2 – Surveyed Municipalities with CSO Mitigation Consent Decrees

GAO obtained information about EPA assistance efforts by conducting interviews of EPA officials and reviewing documents, web pages, and other references.

Here’s a list of the key findings from the report:

Use of Green Infrastructure: Of the 31 municipalities surveyed, 30 reported using at least one type of green infrastructure. While many reported using green infrastructure somewhere, the area within these municipalities that are served by green infrastructure is generally small. Twenty-seven municipalities provided information about how much of the areas subject to CSO mitigation of stormwater permitting drains to gray or green infrastructure.  Of these 27 municipalities, 15 reported that less than 5% of the relevant areas drained to green infrastructure facilities, 6 reported that between 5 and 20% of their area drained to green infrastructure facilities, and 6 reported that more than 20% of the relevant area drained to green infrastructure facilities.

Funding Sources: About three-quarters of the municipalities said that they fund green infrastructure through general revenues and stormwater fees.

Use of Green Infrastructure Deemed Challenging in Certain Ways: Municipalities were asked about how challenging it was to obtain land, estimate capital costs, estimate operations and maintenance costs, design installations, install facilities, afford implementation, be confident in the effectiveness of the installation, and secure political and public support when implementing either gray or green infrastructure solutions.  Municipalities most often listed the following aspects as more challenging for green infrastructure projects than for gray infrastructure projects:

• Estimate capital costs (22 of 30 municipalities)
• Estimate operations and maintenance costs (16 of 30 municipalities)
• Design installations (16 of 30 municipalities)

Greater Awareness, But Not Yet Institutionalized: EPA interviewees report that while many municipalities are aware of green infrastructure, many are not yet using it extensively to manage stormwater. EPA officials have concluded that green infrastructure approaches are not yet institutionalized in a similar fashion to gray infrastructure.

Long Term Planning Efforts Launched: EPA officials reported that they initiated a pilot project with 5 municipalities to develop long-term stormwater plans that incorporate green infrastructure over a 20 or 30 year implementation period, instead of the typical 5 year stormwater permit cycle. GAO recommended that EPA enter into a formal agreement with the five pilot cities to strengthen the collaborations, increase accountability, improve outcomes, and clarify roles and responsibilities, among other things.