Planning and Development Services

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Planning and Development Services

Director: Dale Pernula

stormwaterStormwater Permitting

www.skagitcounty.net/stormwaterpermitting

Skagit County is subject to a National Pollutant Discharge Elimination System (NPDES) permit that can result in significant penalties upon the County and property owners if polluted water is discharged to ditches or streams. Stormwater management is governed by Skagit County Code Chapter 14.32, which received major revisions effective January 1, 2016. All land disturbing activity (except when vested before that date) must manage stormwater consistent with this chapter.

Key Concepts

NPDES Permit Area

The NPDES Permit Area is the area of unincorporated Skagit County defined by the Department of Ecology’s Phase II Western Washington Municipal Stormwater Permit, issued pursuant to the federal National Pollutant Discharge Elimination System. Whether your project is inside or outside the permit area is important to determining your stormwater requirements.

View the NPDES Permit Area map

Stormwater Management Manual

Skagit County has adopted Ecology’s 2012 Stormwater Management Manual for Western Washington, as amended in December 2014, as the Stormwater Management Manual for the entirety of unincorporated Skagit County. The manual, which is standardized across most Western Washington counties, consists of nine Minimum Requirements (MR).

County Stormwater System

The County’s stormwater system includes all of the natural and manmade systems that manage stormwater, including streams and creeks and other natural systems, and the County’s roadside ditches.

Nothing but stormwater may enter the stormwater system.

 

Application Requirements

Skagit County’s stormwater management requirements different depending on whether you’re inside or outside the NPDES Permit Area.

Stormwater Site Plan Requirement
When you submit your building permit application, you must show all the stormwater features you will construct to manage stormwater on your site plan. See the Site Plan Requirements handout for details.

If your project is subject to Minimum Requirement 1, you must prepare your site plan consistent with the Stormwater Management Manual; see Volume I, Chapter 3 for guidance.

Construction Stormwater Pollution Prevention Plan Requirement
All applications must include a Construction Stormwater Pollution Prevention Plan (“Construction SWPPP”) to ensure that clearing, grading, and other construction doesn’t cause erosion and release of sediment into the stormwater system. Your permit will require you to follow your Construction SWPPP.

Most applications may use our Simplified Construction SWPPP form. Review the form to see if you qualify, and submit the form with your application. If your project does not qualify, prepare a Construction SWPPP consistent with Stormwater Management Manual Minimum Requirement 2; see Volume II, Chapter 3 for guidance.

Projects that disturb one or more acres must have site inspections conducted by a Certified Erosion and Sediment Control Lead (CESCL).

Construction Stormwater General Permit
Construction site operators are required to be covered by a Construction Stormwater General Permit if they are engaged in clearing, grading, and excavating activities that disturb one or more acres and discharge stormwater to surface waters of the state. Smaller sites may also require coverage if they are part of a larger common plan of development that will ultimately disturb one acre or more. This permit is issued by Ecology, and it’s the operator’s responsibility to obtain it.


Stormwater Manual

Skagit County has adopted Ecology’s 2012 Stormwater Management Manual for Western Washington, as amended in December 2014, as the Stormwater Management Manual for the entirety of unincorporated Skagit County.

The manual, which is standardized across most Western Washington counties, consists of nine Minimum Requirements (MR). See the Stormwater Management Requirements handout for information on when these Minimum Requirements apply.

MR1 Stormwater Site Plan
MR2 Construction Stormwater Pollution Prevention Plan (SWPPP)
MR3 Source Control
MR4 Preserve Natural Drainage
MR5 Onsite Stormwater Management
MR6 Treatment
MR7 Flow Control
MR8 Wetlands Protection
MR9 Operations & Maintenance

LIDLow-Impact Development (LID)

Low-Impact Development techniques mimic natural processes to manage stormwater, and are frequently cheaper and more attractive than traditional stormwater management techniques.

When is LID required?
LID is the preferred approach to stormwater management countywide. Inside the NPDES Permit Area and the Special Flood Hazard Area, LID techniques are required unless the Administrative Official determines the techniques as not feasible.

LID Techniques

Read our Low-Impact Development handout (PDF) for an overview of required LID techniques. For specifics on implementing techniques, see the Low Impact Development Technical Guidance Manual for Puget Sound (2012, 18mb PDF).

Resources