Hawaii Stormwater Management Law: Statewide Environmental Rules Rules (2026)

Key Facts

Threshold: 1+ acre disturbance
Authority: Hawaii DOH Clean Water
Statute: HRS Chapter 342D
Maximum fine: $25,000 per day

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.

Hawaii Stormwater NPDES Permit Requirements

Key Facts

Full Breakdown

Violations & Penalties

Frequently Asked Questions

Sources

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