stormwater drain

Improving Water Quality By Updating Stormwater Ordinances

March 8th, 2017

from Policy Director, Mike Pisauro

As we built our communities with more and more concrete, asphalt and buildings, the need to address stormwater arose. Our thinking on how to address stormwater has evolved over the years. Until relatively recently, we thought the best was to deal with stormwater was to collect it and pipe it off our properties as quickly as possible. That old way of thinking, in conjunction with the rapid urbanization of New Jersey, has led stormwater to be one of the biggest threats to water quality in our state. According to a 2014 report from the New Jersey Department of Environmental Protection (NJDEP), over 98% of our monitored waters do not meet one or more water quality standards. NJDEP acknowledges that stormwater is a significant contributor to the degradation  of our water. Nationwide stormwater is sixty percent of the contributor to the overall pollution in our waters.

muddy water flowing out of a stormwater outfallThe old way of thinking is not doing enough to restore our waters. It was a good attempt, but in practice we are still falling short: while our current rules may have slowed the degradation of water quality, they have not stopped or reversed the problem. It is time for our approach to stormwater to evolve again.  While the statewide regulations and permitting process need to be updated, municipalities have the opportunity to create and enforce stronger rules.  

The Watershed is encouraging municipalities to better protect their water by enacting enhanced stormwater management ordinances. Jim Waltman, our executive director, presented the Watershed’s recommendations and rationale for improved ordinances to the Princeton Council on January 9th. You can view the council meeting with the presentation.

Reduce the size of projects that trigger the “major” development requirements under the Stormwater Rules.

Under the state regulations, a project only has to implement stormwater management if it is a “major” development, which means that it disturbs more than one acre of soil or adds a quarter-acre of new impervious surface. Under that definition, any project which does not either disturb more than one acre of soil or add a quarter-acre of new impervious surface does not have to address the stormwater that runs off its property. The Watershed suggests reducing the trigger point from one acre to a half-acre of soil disturbance and to reduce the threshold of one quarter-acre of new impervious to 5,000 square feet.  These recommendations will reduce the amount of stormwater flowing off properties and the amount of pollutants that go with it.

Require “minor” projects to address its stormwater.

Currently projects that do not meet the definition of “major” are not required to address any stormwater management on the property. This means these “non-major” projects contributed polluted runoff without any treatment or reductions. Therefore, the Watershed recommends that for every 250 square feet of new impervious cover the developer must capture and retain 500 gallons of stormwater. Five hundred gallons roughly equates to 3.2” of rain, or just under the amount of stormwater generated by the two-year storm in Mercer County. 

The Watershed’s recommendations:

  • Reduce the size of projects that trigger the “major” development requirements under the Stormwater Rules.
  • Require “minor” projects to capture their runoff.
  • Require stormwater management for re-development projects.
  • Require maintenance of stormwater systems.
  • Require a mitigation fee for instances where a project cannot meet its stormwater management requirements.
  • Emphasize nonstructural techniques and green infrastructure in managing stormwater.

Require re-development to address their stormwater.

Under existing rules, a site that does not disturb an acre of soil or creates a quarter acre of new impervious cover does not have to address its stormwater. If the site was built prior to NJ’s stormwater rules that means it is likely that it does not have any stormwater management. If it is redeveloped within the existing footprint there is no requirement for stormwater management systems to be installed. No improvements in the stormwater that runs off the site will occur. Our proposal would require a developer, when considering new and existing soil disturbance or impervious cover, that meets the new definition of “major” development to address its stormwater.

Require maintenance of stormwater management features.

Whether it is a detention basin, drywell, manufactured treatment device, or other stormwater management feature, the maintenance and repair of these systems are vital to their functioning. While maintenance is required under the current rules, we suspect that actual maintenance is the exception, not the rule. The Watershed recommends that municipalities institute a reporting requirement where the property owner is required to conduct quarterly inspections and report their findings to the municipality.  This is similar to a system already in place in Franklin Township.

Mitigation Fee

There may be circumstances where it is impossible or environmentally more damaging to address stormwater onsite. For example, the only place on site to address stormwater would be in a grove of mature trees or a wetland. We certainly do not want to sacrifice one environmental good for another.  The Watershed’s proposal is that in these instances the applicant would be able to obtain a waiver of all or part of their stormwater requirements and pay a fee. That fee would then be used by the municipality to address the stormwater infrastructure.

Emphasize green infrastructure and nonstructural techniques.

There are nine nonstructural techniques in the current rules. Developers are supposed to incorporate them to the “maximum extent practicable.” These techniques include: minimize impervious surfaces and break them up/disconnect them so that stormwater flows over pervious surfaces; protect natural drainage features and vegetation; minimize soil compaction, etc.   

Green Infrastructure is one of the nonstructural techniques. Green infrastructure is a method of addressing stormwater by using vegetation, soils and other elements to restore natural processes of land.  Two of the most recognizable examples of green infrastructure are green roofs and rain gardens. 

Mike Pisauro is the Policy Director of the Stony Brook-Millstone Watershed Association, a member-supported non-profit organization that works to keep water clean, safe and healthy in central New Jersey. For more information about the Watershed Association, including how to volunteer and donate to its efforts, visit or call (609) 737-3735.

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