Stormwater Management Program

Stormwater runoff occurs when precipitation flows over the land and impervious areas such as paved streets and parking lots. Storm drainage systems are designed to decrease flooding by carrying stormwater runoff through drains and underground pipes to nearby streams and eventually the ocean. Storm drainage systems generally do not provide treatment of stormwater runoff so it is important to keep pollutants out of our stormwater before reaching surface waters, such as our rivers and ocean.

The County of Maui works in many ways to protect stormwater and surface waters from pollutants that could negatively impact surface water quality. The County’s goal is to work with community individuals, businesses, large landowners, and State and Federal agencies to foster joint responsibility and positive action to protect our precious surface water resources. 
Stormwater Program

The County’s MS4 NPDES Permit


The 2010 US Census identified Kahului-Pā‘ia as an urbanized area (UA) based on residential population. The boundary of the UA generally includes all of Kahului and Wailuku extending south to Waikapū and from Wai‘ehu to Pā‘ia along the windward coast. The UA designation triggers a requirement for a municipality to obtain a National Pollutant Discharge Elimination System (NPDES) permit for discharge of stormwater from their Small Municipal Separate Storm Sewer System (MS4). The County received their Notice of General Permit Coverage (NGPC), File No. HI 14KE360, for discharges from the MS4 in the UA from the State Department of Health (DOH) in April 2014. This NGPC expired at midnight, December 5, 2016 because of the expiration of DOH’s NPDES General Permit for Small MS4s (Appendix K). The County submitted a Notice of Intent (NOI) to DOH for the Renewal of the NGPC. DOH granted an Administrative Extension to the County’s current NGPC until DOH issues a new General Permit.

National Pollutant Discharge Elimination System (NPDES) Permit


Storm Water Management Program (SWMP) Plan for the Kahului-Pā‘ia Urbanized Area


The County submitted their Storm Water Management Program (SWMP) Plan in August 2014 to the DOH. The SWMP Plan was revised in December 2015 to reflect information gained during initial implementation of the program. The purpose of the SWMP is to implement programs and practices to control polluted stormwater runoff from the County’s regulated MS4.
SWMP Components
  1. Introduction
  2. Public Education and Outreach
  3. Public Involvement / Participation
  4. Illicit Discharge Detection and Elimination
  5. Construction Site Runoff Control
  6. Post-Construction Runoff Control
  7. Pollution Prevention/Good Housekeeping
  8. Tables
  9. Figures
  10. Attachments A-F

What You Can Do


We can all do our part to protect stormwater and our valuable surface water resources by evaluating our own everyday activities and taking precautions to prevent pollution from entering storm drains. Click through the following documents for information and tips to keep our island beautiful.
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Storm Drain Stenciling 


Storm drain stenciling is one way to help educate others to prevent pollution from ending up in our streams and ocean waters. Click on the link below for more information about storm drain stenciling and how to get permission from the County of Maui to conduct a storm drain stenciling volunteer effort.

Resources for Teachers and Parents


We all depend on water every day and yet many of us don’t know where it comes from or the possible routes stormwater can take from our homes to the ocean. Knowledge of stormwater can increase our appreciation of the watershed we live in and the impact we have on it. Teachers and parents can use these fun lesson guides for their students and children to help them broaden their knowledge of stormwater and the simple acts we can take to prevent pollution.

Construction Guidance


Stormwater Concern Reporting


Illicit discharge is any disposal, either intentional or unintentional, of material(s) or waste(s) that can pollute stormwater. You can report illicit discharges or spills to stormwater or surface waters in any of the following ways:
  1. Fill out the Complaint Reporting Form
  2. Contact the Department of Public Works Highways Division (808) 270-7869; 
  3. Via Email  or;
  4. If you see illegal dumping or large spills that could contaminate surface waters or threaten public health, dial 911.
** Please provide as much information as possible, including location, cross streets, type of discharge, water body threatened, nature of the release, and a photo if available.