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Learning Center Homeowner Industry Specific Keiki Corner

Learning Center

Oahu is home to nearly one million residents who have a direct effect on our island environment and water quality both at home and at work.

Cycle of storm water

WHAT IS STORM
WATER?

Storm water suggests large quantities of water (from rain, flooding) at any one given time. Basically, residents should keep three things in mind: 1) Storm water that stays on their property and soaks in is a resource helping replenish our ground water; 2) What does run off should stay as clean as possible before making its way to the nearest storm drain; 3) Unlike the sanitary sewer system, anything dumped into the storm drain system usually flows directly into the nearest stream or drainage channel, usually without any treatment to remove pollutants.

WHAT IS A STORM
DRAIN SYSTEM?

A storm drain system is a series of street gutters, catch basins, ditches, pipes, and man-made channels that move storm water runoff to waterways. The main purpose of a storm drain system, also known as a drainage system, is to prevent flooding in developed areas.

WHERE DOES HONOLULU’S STORM DRAIN SYSTEM LEAD TO?
The City and County of Honolulu’s storm drain system is known as its Municipal Separate Sewer System (MS4). Storm water that is conveyed through the MS4 flows directly to streams and the ocean, and does NOT get treated or filtered.

The City’s MS4 is designed for storm water, not trash or pollutants, and is completely separate from the City’s sewer system.

Polluted Runoff

WHAT IS POLLUTED RUNOFF?
Because impervious surfaces (roofs, driveways, compacted soil, sidewalks, gutters, roads, parking lots, and other urban or developed land) do not allow rain to soak into the ground, the result is urban runoff. This runoff becomes polluted by litter, pesticides, fertilizers, sediment from construction, bare soil, oil, pet waste, grass clippings and leaves that it picks up along the way to storm drains. In addition to rain, various human activities like irrigation and car washing, can also be the source of polluted runoff. When polluted runoff reaches a water body, it can have a harmful impact on the plants and animals in and around the water. It can also affect humans who swim or fish in the water, or whose drinking water comes from the water body.

For more information about water quality, click here.
More information about the storm drain system, storm water pollution problems, and the relationship between the sanitary sewer and storm drain systems are listed in the Resource Library.

WHAT ARE BMPs?
Many simple yet effective methods can be used to help minimize individual runoff. These are called Best Management Practices or BMPs. Some storm water BMPs can be implemented when first planning and building the home and designing the landscape. Others are incorporated into daily activities. The cumulative impact from all residents in a watershed can have a big impact on water quality.

HOW IS STORM WATER POLLUTION REGULATED? The Clean Water Act was established in 1972 with the goal to make US waters clean enough to be swimmable and fishable. To do this, the Environmental Protection Agency (EPA) established the National Pollutant Discharge Elimination System (NPDES) program.

Since the City’s MS4 discharges directly to streams and the ocean, the City is required to obtain an NPDES permit from the State Department of Health. This permit requires the City to reduce the amount of pollutants discharged from the City’s MS4 in order to meet the water quality standards of the State of Hawaii to the maximum extent practicable.

Components of the City’s permit include investigating complaints of pollutant discharges, pursuing enforcement action against dischargers, and requiring licenses for all private storm drain connections to the City’s MS4.

For more information about the City’s NPDES permit, click here.

HOW CAN I HELP REDUCE STORM WATER POLLUTION?
You can make a difference by learning what causes storm water pollution, and doing what you can to prevent it.

Click the links below for more information that is specific to homeowners, industries, and even keiki (children) on how you can help.

     

WANT TO DO MORE?

Click here to GET INVOLVED to reduce the pollution in your community!  Volunteer at a cleanup event, mark storm drains, help give out information about pollution prevention, or just have fun at a community event!