The Maine Stormwater Law

and Rules: Some Basic

ConceptsMarybeth Richardson

Director, Southern Maine Regional Office

MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTIONProtecting Maine’s Air, Land and Water

Chapter 500 – A Brief History

• 1995 – Maine Storm Water Management Law

• 1997 – Chapter 500 Stormwater Management Law Rules 

• 2006 ‐ Stormwater Management Rules last updated 

• 2009 – Stakeholder group discussions

• 2015 – Major revisions

MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

Chapter 500 – 2015 Revisions• New changes effective 8/12/2015

• General standards – options when 95% and 80% treatment levels can’t be met

• Redevelopment standards

• Innovative treatment measures

• Clarification of treatment standards for Site law redevelopment projects

• Rainfall table updates

• Voluntary low impact development credit

MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

Redevelopment

MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

• Treatment requirement based on the pollutant discharge that would occur if stormwater went untreated

• Pollutant ranking based on Table 2 – land uses• Calculate treatment level based on existing 

land use vs. proposed condition• Priority for treatment given to areas with 

highest pollutant ranking to maximum extent practicable

• Developed area must be treated to the level required based on pollutant ranking in Table 3

• Department may allow equivalent treatment or mitigation on an off‐site parcel as alternative if treatment of developed area is impractical

Recertification Requirement

MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

• Submit documentation within 3 months of every 5‐year interval from date of permit issuance

• Inspection of BMPs• Maintenance log for erosion 

control• Proprietary systems – evidence 

of maintenance• DEP may waive if MSGP or 

MEPDES program requirements can be substituted

New Rule: Chapter 501• Allows for payment of 

compensation fees or mitigation through reduction of existing pollutant sources

• Compensation fees only in towns with a “CFUP”

• Mitigation projects can be on‐site or off‐site

• Effective date 1/13/2015

MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

Maine Construction General Permit • Introduced in 2003• Licenses discharges only from construction activities

• Expired in 2008, but coverage continues 

• Threshold activities similar to Stormwater Permit‐by‐Rule

• Applicants who are applying for stormwater or Site Law permits are automatically covered

MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

MCGP Proposed Changes• Definition changes

• Construction in Long Creek watershed

• Emergency‐related construction activities

• Non‐stormwater discharges

• Changes reviewed with EPA

• Draft currently under review

MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

• Increase erosion control where a 50‐foot buffer to surface water cannot be maintained.

• Install sediment barriers downgradient of, and divert runoff to, soil stockpiles.

• Minimize tracking of sediment off the site.• Adequately protect storm drain inlets.• Design sediment basins to provide storage for a 2‐year, 24‐hour storm and remove sediment to maintain at least half the design capacity of the basin.

MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

MCGP: Other potential changes

LID: Low-Impact DevelopmentSite planning and designstrategies intended to replace or replicate predevelopment hydrology through the use of source control and relatively small‐scale measures integrated throughout a site to disconnect impervious surfaces and enhance filtration, treatment, and management of stormwater runoff as close to its source as possible.  

MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

LID continued…• Encourages innovation 

and creativity• Voluntary LID credit• Can be structural or 

non‐structural• LID strategies should 

be agreed upon by DEP early in review process

MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

Stormwater and Climate ChangeDEP Adaptation Toolkit:• Centralized source of information for many stakeholders

• Developed with other state agencies

• Will continue to be updated over time

http://www.maine.gov/dep/sustainability/climate/adaptation-toolkit/index.html

MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

Contact:Land Bureau Licensing Unit

Southern Maine Regional Office207.822.6300

www.maine.gov/dep