New York Model Local Laws to Increase Resilience (Chapter 5: Stormwater Control Measures)
In June 2019, the New York Department of State published model local laws to increase resilience as part of its required actions under the State’s Community Risk and Resiliency Act (CCRA). The model laws are divided into chapters addressing land use and zoning, wetlands and watercourses, coastline protection, floodplain management, and stormwater control. The fifth chapter addresses stormwater control measures, including reduction of impervious surfaces and mitigation where reduction isn’t available, and includes model language local governments can adapt to that purpose.
The natural landscape traps stormwater runoff, filtering pollutants while allowing stormwater to dissipate or be absorbed into the soil. Construction decreases the land’s ability to mitigate stormwater, especially by covering the ground with impervious surfaces like pavement. Interfering with runoff processes creates flood concerns upstream due to impaired drainage and downstream due to increased erosion, while hindering natural filtration of pollutants in the runoff.
Some communities are designated by federal and/or state law as Municipal Separate Storm Sewer Systems (MS4s), and must establish stormwater management programs including discharge permitting requirements for certain operators. New York’s relevant discharge requirements are more stringent than the federal standard, which is reflected in the model laws included in this chapter.
Steep slopes are a common feature that require prudent management to reduce hazards related to stormwater management. Slopes with impervious surfaces or without vegetation can erode and become unstable. Stormwater allowed to run unmitigated off steep slopes can carry debris and pollution into downhill water bodies, or can washout downhill roads. Building on flatter areas helps prevent erosion and minimize runoff, and highly permeable soils can be used as nonstructural stormwater barriers. Regulation related to preserving slopes can protect vegetation, restrict impervious surfaces, and promulgate erosion control standards. The model includes three steep slope regulation examples, including an overlay district related to steep slopes.
Stormwater Management and Reduction of Impervious Surfaces
Municipalities can reduce the amount of impervious surface cover present by amending relevant zoning laws. Rural districts would require more restrictive limits on impervious surface coverage than would commercial or industrial districts. Municipalities can incentivize reduced impervious coverage by including impervious surfaces in calculations of site runoff. This would encourage developers to reduce the need for costly installations of permanent stormwater management features by reducing impervious ground cover instead.
Stormwater laws can also require green infrastructure planning on sites, including reduced impervious cover or preservation of natural features. Such green infrastructure can treat and reuse stormwater, preserve the natural hydrologic cycle of the site, and can aid flood control and air quality. Municipalities can complement state regulations by (for example) requiring green infrastructure in projects above a certain size.
Erosion and Sediment Control
MS4s are required under federal and state laws to adopt regulatory mechanisms to control erosion and stormwater runoff related to construction projects. To mitigate risks of flooding and erosion related to the disturbances these activities cause, municipalities are recommended to adopt similar legal mechanisms. A local permitting process can enforce best practices to reduce risks and protect local water quality. The Stormwater Management Gap Analysis Workbook for Local Officials, developed by New York State, can be used by municipalities to evaluate gaps in regulatory schemes related to stormwater and erosion. Updates on model law developed in conjunction with that Workbook, as well as additional approaches for non-standard cases, are modeled.
New York State’s home rule law allows municipalities to establish a stormwater utility in order to offset some or all costs associated with stormwater management. This allows a municipality to levy fees on property owners to pay for stormwater management as opposed to reliance on property taxes. In considering such an action, the utility should consider 1) the kind of fee to be charged, 2) what the rate will be, 3) whether credit is provided, and 4) public support for the measure. Fees are typically based on causal factors like the percentage of impervious surface coverage on the lot.
Including credits (fee reductions triggered when a permittee undertakes an action the utility wishes to incentivize) can promote best practices, such as by rewarding the use of porous or permeable surfaces or incentivizing the installation of rain gardens. Credits can incentivize maintenance of management structures by requiring annual follow-ups to ensure structures are still present and functional. Municipalities should weigh the value of the revenue with the benefits expected from public participation in the credit system when setting credit amounts. Some land uses, such as refraining from development (retaining 100% pervious ground coverage) can be excluded from utility-levied fees in order to incentive those uses.
The published model does not establish any legally binding standards, and should not be a substitute for a local government’s consultation with an attorney.
Publication Date: June 2019
- New York Department of State - Office of Planning and Development
- New York Model Local Laws to Increase Resilience (Chapter 2: Wetland and Watercourse Protection Measures)
- New York Model Local Laws to Increase Resilience (Chapter 3: Coastal Shoreline Protection Measures)
- New York Model Local Laws to Increase Resilience (Chapter 4: Management of Floodplain Development)
- New York Model Local Laws to Increase Resilience
- New York Model Local Laws to Increase Resilience (Chapter 1: Basic Land Use Tools for Resiliency)
- Best practice
- Policy analysis/recommendations