Monday, December 15, 2008

Iowa (IDNR) Antidegradation Policy - Potential Impacts on Stormwater Permits

The Iowa Department of Natural Resources (IDNR) is proposing changes to its “Antidegradation Policy”. The changes can impact any wastewater discharger in Iowa, but especially new permittees or existing permittees that may wish to increase their discharge in the future. The changes being proposed include:

  • Incorporate by reference the document entitled “Iowa Antidegradation Implementation Procedure,” which proposes an approach to assessing and minimizing degradation of Iowa’s surface waters,
  • Update antidegradation policy language with four tier approach,

  • Remove High Quality (Class HQ) and High Quality Resource (Class HQR) designated uses and add several waters to the newly proposed Outstanding Iowa Water (OIW) category.

Antidegradation policies can potentially have a significant impact on stormwater permitting requirements. Adding new stormwater discharge points, or increasing impervious area could be viewed as “new or expanded” discharge. This could result in extensive antidegradation reviews before proposed projects are allowed permit coverage. However, currently the IDNR is proposing to conduct antidegradation reviews for discharges authorized by general permits will occur for the entire class of general permittees when the general permit is issued. Although additional requirements may have to be met, individual projects would not need to conduct their own antidegradation review under the IDNR proposal.

The purpose of the antidegradation policy is to set minimum requirements to conserve, maintain, and protect existing uses and water quality for water bodies that currently meet their water quality standards. The department is required by Clean Water Act to develop and adopt a statewide antidegradation policy and to identify procedures for implementing the policy. Comments on the draft policy are being accepted through January 29, 2009.

Caltha LLP provides technical support to dischargers needing to evaluate and address their State's antidegradation requirements.

For further information contact Caltha LLP at
Caltha LLP Website

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