Last Updated 07/17/2026
The City of Anchorage has enacted a Stormwater Ordinance in order to establish minimum stormwater management requirements and controls to protect and safeguard the general health, safety, and welfare of the public residing in watersheds within this jurisdiction. The City of Anchorage is the permitting authority for all land disturbing activities and requires the land owner to maintain all on-site stormwater control facilities and all open space areas (e.g. parks or “green” areas) required by the approved stormwater control plan. The City of Anchorage will only provide construction permits to projects that establish a plan to manage stormwater runoff occurring during the construction process. The City of Anchorage, under the NPDES program, also has the authority to inspect properties for noncompliance and can issue a notice of violation (NOV) for any deficiency or infraction onsite. Property owners are responsible for the maintenance of any stormwater facilities or practices located on the property. The City of Anchorage has the authority to inspect stormwater facilities and practices in order to ascertain that they are properly maintained and functioning.
1. Introduction
MOA regulations regarding storm water pollution control are set forth in the Anchorage Municipal Code (AMC) Title 21. The AMC requires the development, implementation, and maintenance of a Storm Water Treatment Plan Review Guidance Manual (SWTPRGM). The AMC further requires anyone who constructs, installs, modifies, or operates a storm water treatment or disposal system to comply with the SWTPRGM regarding storm water runoff system plan requirements and plan reviews.
Developers of both new and redeveloped sites are required to prepare and submit a Storm Water Treatment Plan (SWTP) to the MOA for review and approval prior to the start of construction. This requirement applies to anyone who will disturb the ground or discharge or route storm water within municipal boundaries.
2. State Regulations
2.3.3 Municipal Separate Storm Sewer System (MS4) Permit
The MOA and the Alaska Department of Transportation and Public Facilities (ADOT&PF) are co-permittees under an MS4 permit issued by the EPA and now administered by ADEC. The MS4 permit allows the MOA and ADOT&PF, as operators of a MS4, to discharge storm water meeting specified requirements into waters of the United States. The MS4 permit requirements are implemented through the Storm Water Management Program and include a program substantially similar to the CGP program discussed above.
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In compliance with the MS4 permit, the MOA developed the SWTP program and associated guidances describing MOA storm water treatment requirements, reviews, and inspections. The SWTP program is the basis for this guidance document, which will continue to be updated periodically as EPA and ADEC regulations change or as the MOA revises its program. The MOA SWTP review requirements outlined in this manual apply to all land areas and land disturbances within the corporate limits of the MOA and / or served by the MS4, and refer to those portions of the MS4 that are owned and operated by the MOA or ADOT&PF, and that discharge to receiving waters.
3. SWTP Requirements Overview
Storm water treatment plan approval is required under AMC 21 prior to the commencement of land clearing or ground disturbing activities; the discharge of surface water (including meltwater from snow disposal sites); the construction, alteration, installation, modification, or operation of a storm water treatment or disposal system; demolition or utility work; connection to the municipal storm sewer system; work in waterways or watercourse; or dewatering activities. All construction, development, and maintenance activities shall be in accordance with the approved Storm Water Treatment Plan. The Storm Water Treatment Plan is a comprehensive report containing all of the technical information and analysis necessary for regulatory agencies to evaluate proposed BMPs and determine if minimum requirements will be met. Contents of the plan vary with the size of the parcel, size and type of proposed development, individual site characteristics, and activities and land use associated with the site.
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Frequently Asked Questions
What is a Storm Water Treatment Plan, and does my Anchorage property need one?
A Storm Water Treatment Plan, or SWTP, is a comprehensive report containing the technical information regulators need to evaluate a property’s proposed best management practices. Anyone constructing, installing, modifying, or operating a stormwater treatment or disposal system in the Municipality of Anchorage has to prepare and submit one for review and approval before construction starts. That requirement applies broadly to anyone who will disturb the ground or route stormwater within municipal boundaries, not just large commercial developers.
What activities in Anchorage require SWTP approval before they can start?
More than just new construction. Land clearing or ground disturbance, surface water discharge including meltwater from snow disposal sites, building or modifying a treatment or disposal system, demolition or utility work, connecting to the municipal storm sewer, work in waterways, and dewatering activities all require an approved plan first.
What determines how detailed my Storm Water Treatment Plan needs to be?
It scales to the project. The plan’s required contents vary based on parcel size, the size and type of development proposed, individual site characteristics, and the specific activities and land use tied to the site. A small commercial lot and a large industrial redevelopment won’t need the same level of documentation, but both need a plan on file before work begins.
Who administers Anchorage's stormwater permit, the city or the state?
Both, as co-permittees. The Municipality of Anchorage and the Alaska Department of Transportation and Public Facilities share MS4 permit responsibility, originally issued by the EPA and now administered by ADEC. That permit authorizes both entities to discharge stormwater meeting specified requirements into waters of the United States, and it’s what obligates Anchorage to run its SWTP program in the first place.
Does Anchorage's SWTP program apply to property outside city limits?
The review requirements apply to all land areas and land disturbances within the Municipality of Anchorage’s corporate limits, or anywhere served by the portions of the MS4 that the municipality or ADOT&PF own and operate and that discharge to receiving waters. In practice, that means the geographic reach follows the storm sewer system’s footprint as much as the city boundary itself.
Can Anchorage inspect my property's stormwater system for compliance?
Yes. Under the NPDES program, the city has the authority to inspect properties for noncompliance and can issue a notice of violation for any deficiency found on-site. Property owners remain responsible for maintaining any stormwater facilities or practices on their land, and the city can inspect those facilities directly to confirm they’re properly maintained and functioning.
How can AQUALIS help my property navigate Anchorage's Storm Water Treatment Plan requirements?
AQUALIS helps Anchorage property owners and developers prepare the Storm Water Treatment Plan documentation the city requires before construction, dewatering, or utility work can begin, and supports ongoing maintenance of approved BMPs to stay ahead of city inspections.
The information on this page is provided for general informational purposes only and is not legal advice. Regulations change frequently — AQUALIS makes no warranty as to the accuracy or completeness of this content, and any reliance on it is at your own risk. Consult a qualified professional or your local regulatory authority to confirm requirements applicable to your specific property.
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