Last Updated 08/11/2026
Hawaii stormwater laws & regulations
The State of Hawaii operates under the National Pollutant Discharge Elimination System (NPDES) program through state regulation Hawaii Administrative Rules (HAR) HAR 11-55. The stormwater management permitting and compliance program is administered by Clean Water Branch of the Hawaii Department of Health.
In order to determine if your facility requires a National Pollutant Discharge Elimination System (NPDES) Permit, compare your Standard Industrial Classification (SIC) code with the regulated SIC codes.
1.5.2. State Programs
In Hawaii, Small MS4s, industrial facilities, and construction activities greater than or equal to one acre are normally covered by general permits. However if such facilities discharge storm water into sensitive water bodies designated as Class AA marine, or Class 1 inland State waters, or areas restricted in accordance with the State’s “No Discharge” policy, then those facilities must be covered by an individual permit. Also, Small MS4s and industrial facilities could be covered under an individual permit issued to a Large MS4.
Regulatory emphasis is placed on pollution prevention by regulating “end of pipe” discharges in lieu of setting effluent limits. Prevention is accomplished through the development and implementation of plans such as the MS4 Storm Water Management Program Plan (SWMPP), Industrial Storm Water Pollution Control Plans (SWPCPs), and erosion control plans and Site-Specific BMP Plans (SSBMPs) for construction sites.
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Frequently Asked Questions
Which agency administers Hawaii's stormwater permitting program?
The Clean Water Branch of the Hawaii Department of Health administers stormwater management permitting and compliance under Hawaii Administrative Rules 11-55, the state’s implementing regulation for the NPDES program. Property owners and businesses working through a compliance question in Hawaii are dealing with a state-run program rather than a delegated county or city authority.
How do I know if my facility needs an NPDES permit in Hawaii?
Compare your facility’s Standard Industrial Classification code against the state’s list of regulated SIC codes. Small MS4s, industrial facilities, and construction activities disturbing an acre or more are generally covered under general permits, which simplifies the process for most typical commercial and industrial operations across the islands.
Does discharging near sensitive Hawaii waters change my permit requirements?
Yes, significantly. Facilities that discharge stormwater into waters designated Class AA marine or Class 1 inland, or into areas covered by the state’s “No Discharge” policy, can’t rely on a general permit and instead have to secure an individual permit. Given how much of Hawaii’s coastline and inland water carries these sensitive designations, it’s worth confirming a site’s specific classification early, since it can change the entire permitting pathway for a project.
What does Hawaii's stormwater program prioritize: pollution prevention or discharge limits?
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.
