Part 2: Understanding the Residual Designation Authority (RDA)
In our last Spotlight on Stormwater we talked about the dangers of stormwater runoff from hard surfaces like roads and rooftops. It’s one of the biggest sources of water pollution in Massachusetts! The US Environmental Protection Agency (EPA) estimates that nationwide 10 trillion gallons of untreated stormwater runoff enters US waterways from city storm drain systems every year.
But there’s good news! Each of us can help clean up stormwater, and it starts with understanding the problem.
So we’re thrilled to bring you the second installment in our blog series on stormwater. Throughout this four-part series, we’ll explore the fundamentals of stormwater pollution; who regulates it, tools for tackling the problem, and how sewage overflows contribute to the issue.
Let’s keep exploring with our second installment on stormwater permitting; this time we’ll explore the Environmental Protection Agency’s Residual Designation Authority, or RDA. RDA represents a different way to keep too many stormwater pollutants from entering our water sources. It sounds complicated but it’s actually easy to understand!
Who regulates stormwater and how?
In the first part of our series, we reviewed the definition of stormwater, how it’s generated, and why it’s a problem. We also discussed how stormwater runoff is regulated in Massachusetts, through the MS4 permit system, which is jointly administered by the US Environmental Protection Agency (EPA) and MassDEP. Read the first blog post here if you missed it!
The EPA issues MS4 permits, which regulate discharges of stormwater by municipalities, under the authority of the National Pollution Discharge Elimination System (NPDES), which is part of the Clean Water Act. However, there is another part of the Clean Water Act called the Residual Designation Authority, or RDA. This section gives the EPA the power to regulate other kinds of stormwater pollution if they find that it is detrimental to water quality.
How was the RDA enacted in MA, and what will it do?
The Charles, Mystic, and Neponset River Watershed Associations, along with the Conservation Law Foundation, petitioned the EPA in 2019 and 2020 to use the EPA’s Residual Designation Authority to regulate stormwater generated by private entities in their watersheds. These organizations argued that the unregulated stormwater runoff from places like shopping malls was significantly reducing water quality in their watersheds. They provided evidence of high levels of phosphorus and bacteria in stormwater runoff from properties with large amounts of impervious surface. High phosphorus levels can cause toxic cyanobacteria blooms which are detrimental to human and ecosystem health, and bacteria and pathogens in stormwater can also make water unsafe for recreational use. The evidence provided by these organizations led the EPA to use its Residual Designation Authority to create a new permit system that will apply to certain private entities in the affected watersheds.
Once the permit is issued, each commercial, industrial, and institutional property with impervious surface of one acre or more within the Charles, Mystic, and Neponset Watersheds will have to apply for an individual NPDES permit. The NPDES permits will regulate stormwater pollution from each of these entities' properties. The responsibility for stormwater pollution from these properties will shift from the municipalities to the commercial, industrial and/or institutional entities generating the pollution.
If the new permit system goes into effect, the newly regulated entities, e.g. universities and industrial sites, will have similar requirements in their permits as municipalities do under the MS4 permit. Permittees will have to reduce pollutants in the stormwater runoff from their sites through structural or nonstructural practices. That means, permittees might install structures like permeable pavement and nature-based solutions like rain gardens to allow stormwater to filter into the soil. They may also comply by making sure their waste streams are stored properly, regularly sweeping debris from parking lots, or limiting salt use in the winter.
If you want to know if your property will be regulated under the permit, or find parcels near you that will be regulated, put your address into the EPA’s Residual Designation Authority (RDA) Parcel-Level Interactive Mapping Tool. If you’d like more information about the RDA in general or the CII Permit, you can visit this website.
What’s happening with the RDA now?
The new RDA-based permit (CII) for the Charles, Mystic, and Neponset Watersheds is being reviewed by stakeholders. The comment period for the Draft CII General Permit was supposed to close January 29th, but the EPA has extended the comment period until March 17, 2025. However, because Massachusetts stormwater permits are issued by the EPA, depending on the priorities of the new federal administration, the final permit may not be issued. In that case, the organizations responsible for obtaining the designation from the EPA will have the option to take further legal action to try to get the new permit issued.
The current Draft Permit is exciting because it gives us the opportunity to submit a comment letter that expresses our broad support for the use of the RDA and issuing of the Draft Permit. It also gives us the ability to give constructive criticism on which requirements of the permit we think could be strengthened to improve stormwater pollution elimination and ensure that new permittees are able to meet their permit requirements.
I’m in one of the relevant watersheds, the RDA sounds great! How can I help?
It is great! Since the EPA has extended the comment period until March 17th, we have that much more time to gather more support for the permit. Please help by:
Submitting a comment letter to the EPA saying how great and helpful you think it is for water quality. The Conservation Law Foundation has an easy and simple letter of support on their website that you can submit.
Attending the next public hearing on the CII Permit that the EPA is hosting. You can check this website to sign up for the meeting when it is scheduled.
Signing up for our bi-weekly e-newsletter to stay up to date on what is happening with the RDA permit!
I’m not in any of the relevant watersheds, why should I care?
Even though the RDA was only used to issue a general permit for the Charles, Mystic, and Neponset Watersheds, this designation has wide-reaching implications for the state of Massachusetts and the nation as a whole. There are many other heavily urbanized areas in Massachusetts, like on the South Shore and Connecticut River Valley, where the RDA could be instrumental in reducing stormwater pollution. If the CII permit is successfully implemented in the watersheds around Boston Harbor, it means the chances of it being used to benefit other parts of the state and the country are much higher. So even if you don’t live in the Charles, Mystic, or Neponset Watersheds, please still submit a letter of support for the CII Permit, attend the EPA public hearing to voice your support when it is scheduled, and sign up for our bi-weekly e-newsletter to get RDA updates and other information on stormwater pollution regulation and reduction around the state!
Even if it doesn’t feel like it, every little bit you do to support river health and advocacy is worth it. If the CII permit isn’t finalized, there is still plenty to be done on a state and local level to reduce pollution in stormwater runoff. And you can be involved in these efforts with Mass Rivers!
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