About Honolulu's NPDES Permit and Storm Water Management Plan

The City and County of Honolulu's storm drain system is regulated under a National Pollutant Discharge Elimination System (NPDES) municipal separate storm sewer (MS4) permit. In 1990, the Environmental Protection Agency (EPA) issued rules that required all municipalities with a population of over 100,000 to obtain NPDES permits for their storm drain systems. The EPA has delegated permitting authority in Hawaii to the State Department of Health. The City first received its MS4 permit in 1994 for the five-year period from 1994 to 1999 and has updated and renewed the permit continuously ever since.

The most current permit, NPDES Permit No. HI S000002, was issued on January 16, 2015 by the Hawaii Department of Health to the City and County of Honolulu. The effective date is February 16, 2015 until midnightJanuary 15, 2020.

The storm water permit requires the City to develop and implement a storm water management program plan. The latest plan was submitted to the State Department of Health on June 22, 2012. The plan includes the following elements:

  1. Public Education and Outreach

    The City is required to implement public education and outreach programs to help the general public understand their role in reducing polluted runoff. The learning center provides information specific to homeowners, industries, and even how to educate the keiki (children) on how they can help prevent storm water pollution to storm drains and downstream waters. Also visit the photo gallery to view Adopt-A-Block and Adopt-A-Stream events that show how volunteers are helping make a difference in storm water pollution.

  2. Illicit Discharge Detection and Elimination

    The City is working to implement this program that detects and eliminates illegal connections and illicit discharges to the storm drainage systems by conducting field screening, investigations, enforcement, Spill Prevention Control and Countermeasure Plans (SPCCs) and Storm Water Pollution Control Plans (SWPCPs), while also training staff on illicit connections, illegal discharges, and spills. Additional information on types of illegal connections can be found here.

  3. Construction Site Runoff Control

    The City is working to continue implementing a construction site management program that helps reduce the discharge of pollutants from all construction sites by updating their drainage standards, updating the Best Managment Practices Manual, and conducting soil and erosion control inspections, while also enforcing and training staff on approved BMP plans.

  4. Post-construction Storm Water Management in New Development and Redevelopment

    The City is working to continue implementing a program to address storm water runoff from new development and redevelopment projects that result in a land disturbance of one (1) or more acres. The program includes going through a plan approval checklist that notes installation of permanent post-construction BMPs, reviewing the operation and maintenance plan for those BMPs, inspecting the sites, tracking those inspections through a database, and educating the inspectors along with the parties who apply for the permits.

  5. Pollution Prevention/Good Housekeeping

    The City is developing and implementing a plan to reduce pollutants from all City-owned facilities, roads, parking lots, municipal waste facilities, and the City’s MS4. BMP Program plans are setup for debris, chemical applications, erosion control, and municipal facilities.

  6. Industrial and Commercial Activities Discharge Management Program

    The City is developing and implementing an industrial and commercial discharge management plan to reduce the discharge of pollutants from all industrial and commercial facilities and activities that discharge into the City’s MS4. This includes creating an inventory and map of all facilities and activities, inspecting these facilities, enforcing the policies, and training and educating the inspectors.

Agency Responsibilities

The Department of Facility Maintenance owns, operates, and maintains the municipal separate storm sewer system, which includes street sweeping, storm drain cleaning, roadside litter pickup, and maintenance of City-owned streams, channels, debris basins, and other structural Best Management Practices or BMPs, including the Kaneohe Dam and Kahaluu Lagoon. The City's system has more than 670 miles of pipes and culverts, 20,000 catch basins, and 8,000 manholes.

The Department of Planning and Permitting issues and administers zoning and land use changes, as well as the following permits: building, clearing and grubbing, stockpiling, grading, and construction dewatering. DPP issues private drain connection licenses to the municipal separate storm sewer system and assesses the need for construction of permanent detention/retention and other engineering control structures in large developments on a case-by-case basis. The department  takes enforcement action against illegal grading or construction.

The Department of Design and Construction manages all capital improvement projects done by the City, including plan preparation, funding and administering consultant and construction contracts, studies, designs, and construction management of flood control channels and structures.

For more information, please use the online form under Contact Us.