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Hawaii Statewide Rule

Hawaii Stormwater NPDES Permit Requirements

Heavy RestrictionsApplies statewide across Hawaii (2026)

Key Facts

Threshold
1+ acre disturbance
Authority
Hawaii DOH Clean Water
Statute
HRS Chapter 342D
Maximum fine
$25,000 per day
Last verified: September 5, 2026Source: Hawaii State Legislature

Summary

Hawaii Department of Health administers federal NPDES stormwater permits statewide. Construction sites disturbing one or more acres and certain industrial activities must comply with state-issued permits and best management practices.

§342D-50 Prohibition. (a) No person, including any public body, shall discharge any water pollutant into state waters, or cause or allow any water pollutant to enter state waters except in compliance with this chapter, rules adopted pursuant to this chapter, or a permit, water quality certification, or variance issued by the director. (b) No person, including any public body, shall knowingly establish, extend, or alter any system of drainage, sewage, or water supply, or undertake any project in sewage outfall areas where there may be a possibility of alteration of currents depended upon for dilution without first securing approval in writing from the director.

Source: Hawaii State LegislatureView official code

Full Breakdown

Under HRS Chapter 342D and HAR Title 11 Chapter 55, the Hawaii Department of Health Clean Water Branch issues NPDES permits for stormwater discharges. Construction projects disturbing one acre or more must obtain coverage under the state's general construction permit and implement a Stormwater Pollution Prevention Plan. Industrial facilities and municipal separate storm sewer systems also require permits. Counties enforce local grading and erosion ordinances but must comply with state permit conditions. Discharges of pollutants into state waters without authorization are prohibited.

Violations & Penalties

Unpermitted stormwater discharges face fines up to $25,000 per day per violation under HRS 342D, plus potential cleanup orders.

Frequently Asked Questions

When do I need a Hawaii stormwater permit for construction?
Construction projects disturbing one acre or more require an NPDES general permit from the Hawaii Department of Health, plus a Stormwater Pollution Prevention Plan and best management practices.
Who enforces stormwater rules in Hawaii?
The Hawaii Department of Health Clean Water Branch issues and enforces NPDES permits statewide. Counties may enforce additional local grading rules but cannot override state permit conditions.

Sources

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