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Michigan Modifies Groundwater-Surface Water Interface Pathway Evaluation Under Part 201

June 27, 2012
Environmental Alert

Governor Snyder recently signed into law Public Act 190 of 2012, putting into immediate effect significant reforms regarding how the groundwater-surface water interface (GSI) pathway is evaluated under Part 201 (Part 201) of the Michigan Natural Resources and Environmental Protection Act of 1994, as amended (NREPA). Act 190 is one of several expected substantive amendments of Part 201 that puts into effect recommendations from the Office of Regulatory Reinvention’s Environmental Advisory Rules Committee, which were issued in late 2011, and the Michigan Department of Environmental Quality’s (MDEQ) Collaborative Stakeholders Initiative, which convened in early 2012.

An evaluation of the GSI pathway traditionally has played an important part in many evaluations, investigations, remedial activities, and “facility” determinations under Michigan’s Part 201 soil and groundwater remediation program. In recent years, many property owners, consultants and attorneys have expressed serious concern that the MDEQ’s regulation of the GSI pathway was unduly conservative, leading to properties being unnecessarily considered contaminated (i.e., facilities) because of the unproven possibility that slightly contaminated soil or groundwater could result in contamination of distant surface water bodies, such as streams or rivers, via storm sewers, utility corridors or other routes. Despite previous attempts to address this problem during a prior statutory amendment, rulemaking and issuance of policy documents under Part 201, there remained widespread consensus that the GSI pathway was still an unwieldy impediment to redevelopment and closure under Part 201 at too many properties.

Act 190 addresses the concerns with the GSI pathway in many important ways, including:

Applicability of GSI Pathway:

  • The GSI pathway can be determined to be irrelevant under Part 201 based upon the application of 8 factors without always requiring the use of GSI monitoring wells, and the evaluation may also utilize fate and transport modeling.
  • Act 190 defines “surface water” for the purpose of Section 20e of Part 201 (i.e., for GSI purposes) to not include water in enclosed sewers, drainage ways and ponds used solely for wastewater or storm water conveyance, treatment or control, and subgrade utility runs and utility lines and permeable fill in and around them.

Evaluation Issues:

  • The quality of groundwater that enters a storm sewer that discharges to a surface water body, such as a river, now normally will be evaluated at the point of discharge from the storm sewer to the river, rather than at the point of entry into the storm sewer. Demonstration of compliance may also be made within the storm sewer, with back calculation now permitted.
  • If venting groundwater has no effect or only a de minimis effect on surface water quality, the MDEQ may not require response activity beyond a groundwater evaluation. A person who concludes that venting groundwater has no effect or only a de minimis effect on a surface water body is required to notify the MDEQ, which is allowed 90 days to disapprove the determination. Failure of the MDEQ to act within the 90 day period constitutes final approval of the conclusion.
  • The fact that the entry of contaminated groundwater into a storm sewer owned by an entity subject to the federal municipal separate storm sewer system regulations and a Part 31 permit for the discharges is subject to an ordinance prohibiting illicit discharges does not prevent compliance with the Part 201 GSI requirements.

Technical Issues:

  • A person is now permitted to include an ecological demonstration and modeling demonstration to show compliance with Part 201 requirements related to venting groundwater.
  • Natural attenuation of hazardous substances is now an acceptable form of remediation.
  • A technical impracticability waiver may be granted if compliance with GSI criteria is unachievable.


  • Wetlands are protected for the GSI pathway only if the particular designated uses under Part 31 of NREPA, which are specific to that wetland, would otherwise be impaired by contaminated groundwater venting to the surface water in the wetland.

Self-Implementation Issues:

  • A Part 201 liable party may self-implement a GSI evaluation and decide based on alternative monitoring points, an ecological demonstration, or a modeling demonstration to not take additional response activities, provided that the party notifies and seeks the approval of the MDEQ.
  • A party who is not liable under Part 201 may implement response activities that rely on a modeling demonstration, an ecological demonstration, or both, without notice to or approval by the MDEQ.

Retroactive Effect and Reopeners:

  • Act 190 has retroactive effect. A person subject to a judgment, consent judgment, order, consent order or agreement, or a remedial action plan or other Part 201 response activity plan entered or approved prior to June 20, 2012 may seek the benefit of any of the changes enacted in Act 190 by seeking court or MDEQ approval of the retroactive application of the changes enacted in Act 190. The MDEQ is prohibited from opposing or denying such a request.


  • Act 190 repeals Part 201’s Rule 716, which established GSI compliance requirements. Several of the former rule’s provisions are now enacted in the statute.

It is anticipated that Act 190 will lead to increased efforts to address and resolve more contaminated properties under Part 201 where previous efforts were stymied or avoided due to difficulties with the GSI pathway.