Letter to EPA leader outlines need to support nationwide community stormwater projects to safely replenish their groundwater supplies.

(WESTERVILLE, OH — October 29, 2020) The National Ground Water Association (NGWA) and the Groundwater Protection Council (GWPC) are calling on the U.S. Environmental Protection Agency (EPA) to support funding for communities needing assistance in managing their water resources and stormwater reuse programs. Both organizations are urging that stormwater reused to recharge aquifers utilize stormwater infiltration design that protects groundwater quality.

In a letter sent to EPA Administrator Andrew Wheeler and Assistant Administrator for Water David Ross, NGWA and GWPC report that groundwater quality can often be vulnerable to contamination from untreated stormwater. Communities across the country need funding and guidance from the EPA for appropriate steps to protect their groundwater supplies. In particular, small systems relying on groundwater and having limited resources as well as larger water systems with groundwater wells for back-up supply need adequately engineered stormwater infiltration solutions.

The Clean Water Act National Pollutant Discharge and Elimination System’s Municipal Separate Storm Sewer System (also known as MS4) permit process requires municipalities to control their stormwater to keep its pollutants from streams and surface waters. The EPA has promoted infiltration of stormwater to the subsurface as a key stormwater pollutant disposal means [1]. The EPA plans to evaluate communities’ capabilities to finance stormwater controls. NGWA and GWPC argue that by not properly addressing funding issues to create the infrastructure needed to address stormwater contamination of groundwater, the EPA is creating risk for concentrating pollutants in groundwater, potentially encouraging new and uncontrolled nonpoint pollution sources, and potentially increasing the cost of additional groundwater treatment methods to communities and private well owners.

Nationally, there are more than 34 million people who rely on groundwater from private wells and 73 percent of community water systems serving 10,000 or fewer people also rely on groundwater as their primary water source. A review of most of the over 7,000 MS4 communities suggests that at least 22 percent of the MS4 communities (nearly 1500 communities nationwide) may be groundwater-supplied, potentially affecting at least 36 million people. Some MS4 communities have more than one groundwater supplier or have adjacent communities that are groundwater-supplied, potentially adding up to 300 water systems and populations they serve, as well as nearby homes on private wells. Fifteen states have from 31 percent to 100 percent of their MS4 communities that may be supplied by community groundwater systems. Sixteen percent of the MS4 communities that are groundwater-supplied are served by small systems having 3300 or fewer customers. These small communities may also need financial support to maintain stormwater controls. These figures may be underestimates as location matching using the stormwater and drinking water databases [2] was difficult for some systems and EPA had not added all the small MS4 municipalities and jurisdictions to the 2009 survey list used to compile these results.

An example of the problems presented by stormwater infiltration affecting groundwater quality from the effects of stormwater collected by infiltration ponds is the Glendale Wellfield in New Castle County, Delaware. High chloride concentrations in infiltrated stormwater from winter road salt use has changed the geochemistry of groundwater, causing radium to come into solution at concentrations above the EPA drinking water maximum contaminant level of 5 pCi/l [3]. Other contaminants potentially carried by stormwater include dissolved metals, fertilizer, organic chemicals, pesticides, and pathogens [4]. Subsurface infiltration design alternatives should provide adequate pretreatment before infiltration and/or sufficient attenuation and degradation underground before water reaches an aquifer used for water supply.

“Financial assistance to communities should include consideration of appropriate design and treatment of stormwater control measures that address protecting groundwater from contamination. Small water systems will likely need financial assistance for both groundwater-protective stormwater infiltration construction and maintenance,” said Chuck Job, NGWA regulatory affairs manager.

[1] U.S. Environmental Protection Agency. 2019. Implementation of Integrated Planning in Accordance with the 2019 Water Infrastructure Improvement Act (WIIA); memorandum from Sally Gutierrez, Acting Director. Water Permits Division, to Water Division Directors, Regions I-X, dated December 3, 2019.

[2] U.S. Environmental Protection Agency. 2020. Government Performance Results Act Drinking Water Tool. GPRA [Drinking Water] Inventory Report. https://obipublic.epa.gov/analytics/saw.dll?PortalPages; U.S. Environmental Protection Agency. 2014. National Pollutant Discharge Elimination System Inventory of Phase I and Phase II MS4 permittees in 2009. File: TEMP-All MS4s_6-5-14 2014.

[3] Rambo, Douglas. 2018. The Unintended Risks to Underground Sources of Drinking Water from Stormwater Infiltration Practices. Presented to the American Geophysical Union Annual Conference, December 12, 2018, Washington, DC.

[4] U.S. Environmental Protection Agency. 2016. Underground Injection Control (UIC), Stormwater Drainage Wells. https://www.epa.gov/uic/stormwater-drainage-wells

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The National Ground Water Association is a not-for-profit professional society and trade association for the global groundwater industry. Our members around the world include leading public and private sector groundwater scientists, engineers, water well system professionals, manufacturers, and suppliers of groundwater-related products and services. The Association’s vision is to be the leading groundwater association advocating for responsible development, management, and use of water.