Small Site Permit Thresholds:

Any project meeting the criteria listed below will need a Small Site permit:

  • Shore Impact Zone Alteration

This includes any alteration to the structures, land, or vegetation within the Shore Impact Zone (one-half the distance of the required building setback from the Ordinary High Water level, i.e. 75 Structure Setback = 37.5 foot Shore Impact Zone)

    • Rip-rap: installation, repair, additions, or modification
    • Sand Beach Blanket: installation, repair, additions, or modification
    • Ice Pressure Ridge Repair
    • Vegetation Removal or changes, including trees, shrubs
    • Best Management Practice installation, changes, removal.
    • Land Alteration:  grading/filling, or any other activity which disturbs soil and has potential for erosion.
    • Impervious Surface: installation, repair, addition, or modification to any impervious surfaces (sidewalks, staircases, patio, sheds, etc.), small site stormwater management plan may be required
  • Bluff and Bluff Impact Zone Alteration

A bluff is defined as a land feature and rises more than 25 feet or more above the Ordinary High Water level and has a average slope of 30% or more.  A Bluff Impact Zone extends 20-feet behind the top of the bluff.  A permit is required for any activity that disturbs soil or vegetation within the Bluff Area or Bluff Impact Zone

  • Steep Slope Alteration

Defined as having an average slope of more that 12% over a distance of 50-feet.  Permits are required for any land alteration/disturbance or vegetation removal.

  • Impervious Surface Coverage

Impervious Surface coverage exceeding 25% total cumulative lot coverage, new/re-constructed and existing surfaces (see large site permit for more than 10,000 S.F coverage), small site storm water management plan is required.

 Small Site Storm Water Management Plan Requirements

Projects that require a small site storm water management plan will need to show that storm water from all impervious surfaces that require treatment are conveyed to an appropriately sized storm water Best Management Practice, BMPs (i.e. rain garden, underground infiltration basin, etc).  The size of the practice will need to be sized appropriately with the capacity to infiltrate a 1.1" rain event over the impervious surfaces that drain to it. 


Permits are issued for projects which meet or exceed certain thresholds.  These thresholds are based on the location of the project and the impervious surface coverage (size) of the project. The thresholds target activities that have a potential to could degrade water resource with increased runoff, pollution, and erosion.  Follow the guidance below to determine if a permit is required.

Large/Commercial Storm Water Management Permit Thresholds:

*Permit required for projects which include construction of new or reconstruction of existing impervious surfaces meeting the total cumulative lot overages below

Note:  Impervious surface coverage totals include new (or reconstruction) and existing impervious surface coverage

  • Commercial Project exceeding 25% impervious surface lot coverage
  • Project exceeding 10,000 S.F. impervious surface coverage within a Shoreland District (1,000 feet from a lake, 300 feet from a river)
  • Project exceeding 1 acres impervious surface coverage
  • Subdivision, Plats, Planned Unit Developments, Developments based on certified survey
  • Changes to, including construction or re-construction of storm water infrastructure, private or public highways, roads, streets, parking lots, Public Water Access, culverts, and inlets to Waters of the State
  • Temporary ground de-watering to Waters of the State

 Projects that meet or exceed the above threshold will require a storm water management plan.

 Please refer to the below Memo from the District Engineer for design of the Plan

Technical Memo for Permit Application Submittal -Best Practices for the Design of Storm water Management Systems (November 2018)

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