Below are EPA's National Pollutant Discharge Elimination System (NPDES) municipal separate storm sewer system (MS4) final permit and supporting documents for the Ada County Highway District (ACHD) in Idaho.
- Permit number: IDS028185
- Effective date: February 1, 2021
- Permit expires: January 31, 2026
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NPDES Stormwater Permit, Ada County Highway District MS4, #IDS028185 (PDF)(62 pp, 649 K,
December 8, 2020)
Final stormwater permit.
Appendix B1: Stormwater Management Program Template, MS4 Permit #IDS028185 (PDF)(25 pp, 1 MB)
Optional template for creating or revising Stormwater Management Program (SWMP) document.
Appendix B2: Annual Report Form, MS4 Permit #IDS028185 (PDF)(21 pp, 848 K)
Format for annual report. Due no later than December 1 of each year.
NPDES Permit Fact Sheet for Ada County Highway District MS4, Canyon Highway District No. 4 MS4, and Idaho Transportation Department District 3 MS4 (PDF)(65 pp, 2 MB,
Technical basis for NPDES stormwater permits: #IDS028185, #IDS028134, #IDS028177.
Response to Comments on Draft NPDES Permit for Ada County Highway District MS4, Idaho, #IDS028185 (PDF)(15 pp, 3 MB,
EPA's responses to public comments on the September 2020 draft permit.