Mililani stormwater is regulated under ROH Chapter 43 Article 11, which prohibits most non-stormwater discharges to the city's separate storm sewer flowing to Waikele Stream.
Honolulu's MS4 ordinance covers Mililani even though the community is inland. Section 43-11.12 governs connections to the separate storm sewer, and Sec. 43-11.22 bars discharging anything other than stormwater into the system. Administrative Rules Relating to Water Quality adopted under ROH 14-12 set pollutant thresholds and best management practices. Mililani's stormwater drains to Waikele Stream and ultimately Pearl Harbor, which has heightened pollutant concerns due to historic impairment. Typical residential issues include car-wash runoff, fertilizer and pesticide overspray, pet waste, and construction sediment.
Illicit discharges, construction BMP failures, or unauthorized storm sewer connections can bring significant civil penalties.
See how other cities in Honolulu County handle stormwater management.
See how Mililani Town's stormwater management rules stack up against other locations.
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