Urban and suburban runoff is the single largest source of water quality problems in Massachusetts, according to the Department of Environmental Protection (DEP). Accordingly, DEP has now issued new storm water standards that apply to all projects over certain thresholds listed below. The policy consists of standards that will be applied during routine project review under the Wetlands Protection Act. Applicants must now submit a new Storm Water Management Form showing how the standards will be met. Projects to be affected include site preparation, construction, redevelopment, and ongoing operations of the following projects:

• industrial projects,
  
  
• commercial projects,
  
  
• institutional projects,
  
  
• residential subdivisions greater than nine lots,
  
  
• residential subdivisions with 5-9 lots that will affect a critical area, or four or less if a critical area is potentially affected, and roadway projects.

Any of the above projects are subject to the new standards if the project is otherwise subject to Conservation Commission review due to wetlands or other resource involvement. The standards are listed below. If one cannot be met, the applicant must demonstrate how an equivalent level of environmental protection will be provided or face disapproval.

Summary of the New Standards

• No untreated, direct storm water discharges to wetlands or waters are allowed.
  
  
• Post development peak discharge rates cannot exceed pre-development peak rates.
  
  
• Post development annual groundwater recharge should approximate pre-development annual recharge conditions.
  
  
• Developers must remove 80% of the average annual load of total suspended solids from new developments.
  
  
• An approved list of specific storm water Best Management Practices (BMPs) must be used for critical area discharges or discharges from areas with higher potential pollutant loads.
  
  
• Redevelopment storm water management systems must improve existing conditions and meet standards to the extent possible.
  
  
• Erosion and sediment controls must be implemented to prevent impacts during construction or other land disturbing activities.
  
  
• All treatment systems or BMPs must have operation and maintenance plans to ensure that systems function as designed.

Implementation of the new standards will be through the local conservation commissions or DEP under the Wetlands Protection Act. For remediation of existing discharges, DEP may use its authority under the Clean Water Act. More detailed information on pre-approved BMPs will be published in future technical briefs on this subject.

For more information on Storm Water Management Policy, contact us 800-725-2550.

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