Monday, January 26, 2009

EPA Stormwater Antidegradation Requirements - New or Expanded Discharges

The US EPA Multi-sector General Permit promulgated in 2008 (“MSGP-2008”) includes antidegradation requirements that apply to new and/or expanded discharges of stormwater from regulated industrial sites.

[What is an Antidegradation Policy?]

EPA’s approach to antidegradation requirements is based on three categories of “special” waters – Tier 2, Tier 2.5 and Tier 3. [Read more about how Stormwater Antidegradation Tiers are defined]


Tier 2. For new or existing dischargers to Tier 2 waters, the discharger is required to notify US EPA prior to making changes at the site which “qualify the facility as a new source or that could significantly change the nature or significantly increase the quantity of pollutants discharged”. EPA may notify the facility that additional analyses, control measures, or other permit conditions are necessary to comply with the applicable antidegradation requirements, or notify the facility that an individual permit application is necessary.

Tier 2.5. Same requirements as Tier 2.

Tier 3. New or existing discharges to Tier 3 waters can not be permitted under the MSGP-2008.

Caltha LLP assists companies in addressing their requirements under State and Federal stormwater rules. Caltha specializes in developing cost effective corporate-wide SWPPP programs covering multiple facilities. Click here to request further information on Stormwater and SWPPP Services.

For further information contact Caltha LLP at
Caltha LLP Website

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