District of Maui


Maui Stormwater laws & regulations

The District of Maui regulations are compliant with the National Pollutant Discharge and Elimination System (NPDES) permit requirements for the Maui District Municipal Separate Storm Sewer System (MS4). The Maui District MS4 spans all storm drains within the urbanized area of Kahului along state-owned roadways. The permitting and compliance program for the District of Maui is administered by the Department of Transportation, Highways division, Maui District (DOT-HWYS).

EXCERPT-Maui Storm Water Management Program Plan, December 2016

3.2.1 Examining Regulatory Issues

A request for a physical connection or permission to discharge surface storm water runoff to the Maui District MS4 is made by submitting two separate forms as follows. For both a connection permit and a discharge permit, the applicant (owner or authorized representative of the owner applying for the permit) shall submit a completed Application for A Private Storm Drain Connection and/or Discharge Permit to the State of Hawaii Highways Division Storm Drain System (see Appendix C.1).

For a connection permit, the applicant shall also complete and submit a Permit for Connection to the State Highways Drainage System (see Appendix C.2). For a discharge permit, the applicant shall also complete and submit a Permit to Discharge into the State Highways Drainage System (see Appendix C.3).

For each connection/discharge location, the applicant is required to submit information on the connection/discharge location, size, type of discharge, flow rate, and a Drainage Report, if applicable. In addition, the applicant is required to indicate whether the subject property or facility (project) generates storm water associated with an “industrial” activity. If so, the applicant must submit analysis of a storm water sample performed by a laboratory acceptable to the State within one year after the date of the connection/discharge. Owners of properties associated with certain types of industrial activities are required by 40 CFR 122.26(c) to obtain NPDES permit/permit coverage for industrial activities, which requires them to monitor storm water discharges that leave their property, regardless of whether the activity or facility directly or indirectly discharges into the Maui District MS4. Those property owners under NPDES coverage for industrial activities are required to report monitoring results directly to HDOH.

If the subject project disturbs one acre or greater, including construction sites less than one acre that are part of a larger common plan of development or sale that would disturb one acre or more, the applicant for a connection permit is also required to submit a permanent BMP plan with the application, including documentation for future maintenance. If a permanent BMP plan is not included, the applicant must submit documentation demonstrating that the project is either exempt from permanent BMP requirements or qualifies for a variance from permanent BMP requirements. (see Section 5.2.1, HDOT Highways Storm Water Permanent Best Management Practices Manual, Section 3—Appendix E.1.A, and HDOT Harbors Post-Construction Stormwater Management in New Development and Redevelopment, Section 1.2—Appendix E.1.B).

Applicants for both connection and discharge permits are required to disclose whether the subject facility, activity or property requires NPDES permit/permit coverage. If so, the applicant must attach a copy of the NPDES permit/permit coverage with the application. If the property does not have an NPDES permit, but Maui District finds based on information contained in the application that the property appears to be engaged in an activity that requires an NPDES permit/permit coverage, the applicant is referred to HDOH for consultation. A Maui District MS4 connection or discharge permit is not issued until either the applicant secures NPDES permit/permit coverage or a determination from HDOH that NPDES coverage is not required.

supplemental documents:

Maui Storm Water Website