Frost Protection Regulation


Anyone who diverts water for frost protection from the Napa River between March 15 and May 15 each year is required to participate in a water distribution program, as described in Section 735 of the California Code of Regulations, and a 1976 Permanent Injunction issued by the Napa County Superior Court.

The water distribution program is administered by a Watermaster appointed by the State Water Board, based on the requirements outlined in the Permanent Injunction. The Department of Water Resources acted as the Watermaster until July 2019, but did not renew its agreement with the State Water Board to administer the program. As a result, the Division of Water Rights will administer the program on an interim basis until a new Watermaster can be appointed. The Division intends to administer the program by continuing the Department’s process from previous years in an effort to minimize any disruption to the existing participants for the upcoming frost season.

2023 Napa River Frost Protection Distribution Program Pump Charts

These pumping tables specify the maximum diversion amount and pumping duration allowed in each 24-hour period between March15 and May 15, relating to stream flow in the Napa River measured at USGS monitoring location 11458000 (Napa River near Napa, CA). Real-time flow values for this location can be found on the USGS website at:

Please note that the flow rate of the Napa River should be checked periodically while you are pumping so that you can make adjustments as needed to not exceed your allotment.

You may receive updated pumping information from the Watermaster via email, to the account listed on your Information Fact Sheet, during frost periods that last two or more days."

Subscribe to our Napa River Frost Protetion email list to receive notifications and the latest updates. After subscribing, you will need to check your email host for a confirmation email to complete the subscription.

Email Address: (required)
Your Full Name: (required)
(e.g. John Smith)

  Subscribe to our other email lists. See the "Water Rightssection.

Contact Us


Phone: (916) 323-0357