New Storm Water Rules Take Effect in Minnesota

The state of Minnesota has adopted new storm water rules effective August 15.

These rules require permit coverage for municipally owned and operated industrial facilities, publicly owned and operated Municipal Separate Storm Sewer Systems (MS4s) located in urbanized areas, and construction activities that disturb one acre or more of soil or are part of a common plan of development that disturbs one acre or more.

The rules will follow the federal expansion of the conditional no exposure exemption, which allows industrial facilities to apply for exemption from permit coverage if they can verify that they have no industrial material or activities exposed to storm water.

The rules will allow the general public a method of petitioning to have additional small MS4s regulated under the municipal storm water general permit.

In addition, they will ease the process for one to five acre soil disturbances for emergency construction and feedlots to obtain permit coverage.

These rules also require municipalities with populations fewer than 100,000 that own or operate industrial type facilities, which were temporarily exempted under the federal 1991 Intermodal Surface Transportation Efficiency Act, to obtain permit coverage. Municipally owned or operated industrial facilities would include transportation and sand and gravel mining.

Minnesota's storm water rules now emulate federal rules and require about 200 Municipal Separate Storm Sewer Systems located in federally defined urbanized areas to be regulated under a National Pollutant Discharge Elimination System/State Disposal System (NPDES/SDS) permit.

The communities have been under permit coverage since 2003, as required by the original federal rules. Some of the fringe suburban communities had only part of their jurisdictional boundary within these urbanized areas. This rule now expands permit coverage for the entire city or township, not just the portion located in the urbanized area.

Publicly owned military bases, hospitals, prisons or correctional facilities, colleges or universities within an urbanized area with a potential average bed occupancy rate of 1,000 or more, are also required to have permit coverage.

The rules also require cities and townships to apply for permit coverage within 18 months of the effective date of this rule if their populations are 10,000 or greater or 5,000 or greater and may discharge storm water to Outstanding Resource Value Waters, trout lakes or streams, or impaired waters.

Communities that qualify at the time this rule was published may be found at:


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