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Cupertino, CA Environmental Rules: Stormwater Management (2026)

Heavy Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Key Facts

Governing chapter
Municipal Code Chapter 9.18
Enforcing official
Director of Public Works
Accidental discharge report
Immediate notice, written statement within 5 business days
Inspector compliance window
Up to 10 business days after violation noted
Illicit connection penalty
Up to $25,000 per day per violation
Violation classification
Misdemeanor under Chapter 1.12

Summary

Cupertino bans discharging anything other than stormwater into its storm drain system, watercourses, or San Francisco Bay under Chapter 9.18. The Director of Public Works administers the rule under the City's Municipal Regional NPDES Permit, and violators face misdemeanor prosecution plus civil penalties reaching twenty-five thousand dollars per day for illicit-connection discharges.

It is unlawful to cause, allow, or permit to be discharged to any public or private lands, any discharge not composed entirely of stormwater to the storm drain system or to surface waters or to any location where it would contact or eventually be transported to surface waters, including flood plain areas, unless specifically called out in the Municipal Regional Permit as an exempt or conditionally exempt discharge. ... City may, from time to time, by resolution of the City Council adopt supplementary policies, rules and regulations on discharge into any storm drain or watercourse which shall have the same force and effect as if set forth herein and for which the remedies herein for violation shall be applicable.

Full Breakdown

18 implements the Municipal Regional Stormwater NPDES Permit that the San Francisco Bay Regional Water Quality Control Board issued to the City on October 14, 2009. 040 makes it unlawful to discharge anything but stormwater into the City's storm drain system, surface waters, or any location where it would reach a watercourse, unless the Municipal Regional Permit lists it as an exempt or conditionally exempt discharge. The prohibition covers pool water, carwash water, sediment, stockpiled material, rubbish, and hazardous materials left where they threaten to reach a drain.

Categorically allowed discharges are limited to items such as natural spring flows, rising groundwater, and single-family foundation and footing drain water. 015, administers and enforces the chapter and may delegate that authority to other City staff. 070. 195. 260. Penalty funds are deposited into the City's Environmental Storm Management Account.

Violations & Fines

A first offense is a misdemeanor prosecuted under Chapter 1.12, and the City may also seek civil penalties up to $25,000 per day per violation for discharges made through illicit connections under Section 9.18.240, or petition the Superior Court under Government Code Section 54740 to recover those sums. Administrative citations under Chapter 1.10 and re-inspection fees also apply, and each day a violation continues counts as a separate offense.

Frequently Asked Questions

Can I wash my car in my driveway in Cupertino?
Washing water containing soap counts as a non-stormwater discharge under Section 9.18.040, and letting it reach the street, gutter, or storm drain is unlawful. The code specifically lists carwash water among the discharges that threaten the storm drain system, so runoff must be contained or directed to a landscaped area or the sanitary sewer instead.
Who enforces Cupertino's stormwater ordinance?
The Director of Public Works administers Chapter 9.18 under Section 9.18.015 and may delegate enforcement to other City staff. Inspectors monitor construction sites and businesses under Section 9.18.195 and can require corrective action before the next anticipated rain, and no later than ten business days after a violation is first noted.
What happens if I accidentally spill something into a storm drain?
Section 9.18.070 requires immediate notification of the Director of Public Works, followed within five business days by a written statement describing the cause and the steps taken to prevent it happening again. Notifying the City does not excuse you from civil penalties or the fines the City may owe the state under the California Water Code.

Sources & Official References

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