New state regulations are forcing Maine’s most populated communities to step up efforts to reduce untreated stormwater runoff that carries litter, motor oil, road salt, fertilizer, pet waste and other pollutants into Maine waters.

Municipalities that contain what the U.S. Census defines as “urbanized areas” are now required to implement more stringent water quality testing procedures for stormwater and take actions to restore the water quality of “urban-impaired” waterways. By 2024, these 30 Maine towns and cities must also require developers to implement low-impact development practices for new construction and redevelopment projects that disturb an acre or more of land.

These requirements, among others, took effect July 1 as part of revised Clean Water Act permits for municipal storm sewer systems. The new permits include clearer standards and require communities to ramp up existing measures to protect seafood supplies, recreational resources and aquatic life from pollutants flushed into waterways. One visible result of stormwater pollution is green algae that bloom in ponds, lakes and on mudflats in Casco Bay, the result of nitrogen and phosphorous in soil that gets washed into waterways.

“This is one of the few really strong legal tools that we have to reduce stormwater pollution,” said Casco Baykeeper Ivy Frignoca of Friends of Casco Bay. Frignoca advocated for the permit revisions and said strengthening the permit requirements will help tackle an expanding problem. “As we continue to grow as a state … (we should) do it in ways that complement and protect our water resources.”

The costs of the new measures will vary depending on the municipality and what work is needed, said Portland Stormwater Program Coordinator Doug Roncarati. For example, he said, Portland will need to conduct studies on its urban-impaired streams before determining what needs to be done to improve the water quality. Increased costs can come from more staffing time spent on watershed management planning efforts and potentially hiring contractors.

“There’s a lot of unknowns because some of these things we find along the way,” Roncarati said. “And then we have to try to figure out what the actual problem is, and then go from there.”

Instead of relying only on visual inspections, permitted municipalities are now required to test any water being discharged from pipes or ditches during dry periods when there shouldn’t be stormwater coming out. Different types of tests can be done, including laboratory testing for bacteria, ammonia test strips and chlorine tests using handheld meters.

If contamination is found, municipalities will also need to resolve the pollution at its source.

“Sometimes what we’re seeing coming out is just plain old groundwater, but we will be looking at that more closely to make sure … it’s not something that shouldn’t be coming out of there, such as somebody dumping in there or cross-connection with the sewer system,” Roncarati said.

The 30 affected communities are also required to provide measurable standards in the ordinances they create for low-impact development. The specific requirements are still being developed by a statewide committee creating a model ordinance for municipalities, said Damon Yakovleff, environmental planner at the Cumberland County Soil and Water Conservation District.

“The way that the low-impact development ordinances are going to work, they’re going to affect several different municipal ordinances, including subdivision and site planning and then other zoning ordinances,” Yakovleff said. “So it’s going to be somewhat complicated to implement, and we’re providing as much support as we can.”

Low-impact development can refer to a wide range of techniques that encourage rainwater to naturally sink into the ground, filtering through soil instead of going straight into storm drains.

It could be “green infrastructure” such as rain gardens, which are essentially gardens sitting on top of filter mediums. It could be “gray infrastructure,” in which filter mediums sit underneath tiling designed for water to seep through cracks. Other techniques include vegetated rooftops, porous pavement that allows water to penetrate through and other infrastructure that directs water into soil instead of onto pavement.

Since the definition of low-impact development is broad and the extent to which it should be implemented is subjective, more specific language in the ordinances will help developers, engineers and planning boards better understand what the requirements are, said Dan Riley, vice president of engineering for Sebago Technics.

“The details come down to how much vegetation do you need to drain across and how steep can it be, and what does the vegetation need to look like. Those things right now are very subjective,” Riley said. “Sometimes applying a number to something makes it easier to demonstrate that you’re meeting a standard than some subjective standard.”

Education and outreach requirements in the revised permit are slightly more stringent as well. South Portland Stormwater Program Coordinator Fred Dillon said many people don’t know there’s a difference between wastewater, which gets treated before it gets discharged, and stormwater, which doesn’t.

“Just last week, I had two reports of swimming pools being emptied into the stormwater system,” Dillon said. “If there’s excessive chlorine concentrations, and that chlorine is directly discharged to a small stream, it could actually kill stuff in the stream.”

Climate change can worsen the issue of polluted water, whether from stormwater or sewage overflow.

As the climate warms, the Northeast region of the U.S. is expected to see increased annual rainfall and more extreme precipitation events. The decade from 2005 to 2015 was Maine’s wettest decade on record, according to the Maine Climate Office.

“Part of it is that there’s more moisture that’s available to fall as rain,” State Climatologist Sean Birkel said. “This process of increased heating increases evaporation, which in turn increases the humidity of the atmosphere.”

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