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 is covered under Hawai‘i Administrative Rule 11-55, Appendix K, NPDES General Permit Authorizing Discharges of Storm Water and Certain Non-Storm Water Discharges from Small Municipal Separate Storm Sewer Systems.

Stormwater Management Plan (SWMP) for the Kahului Pā‘ia Urbanized Area

The County of Maui, Kahului-Pā‘ia Stormwater Management Plan (SWMP) serves as additional NPDES permit conditions for the County of Maui, Kahului-Pā‘ia Small MS4 to regulate and impose water pollution control requirements on the discharge of stormwater and certain non stormwater discharges to receiving State waters, to meet the MS4 permit standard, and to protect water quality. 

The SWMP is intended to reduce the discharge of pollutants from the County of Maui, Kahului-Pā‘ia MS4 to the maximum extent practicable to protect receiving water quality and satisfy the requirements of the Clean Water Act. The SWMP focuses on the implementation of measures to prevent pollution from entering the County of Maui, Kahului-Pā‘ia  MS4. Many of the measures put in place to meet the requirements of the MS4 Permit will also benefit other areas of the County. These measures include ordinance revisions, rules revisions, guidance documents, and public outreach and education.

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.

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.