California Land Conservation Act

The California Land Conservation Act of 1965 - referred to as the Williamson Act - enables local governments to enter into contracts with private landowners for the purpose of restricting specific parcels of land to agricultural or related open space use. In return, landowners receive property tax assessments which are much lower than normal because they are based upon farming and open space uses as opposed to full market value. The Act is estimated to save agricultural landowners from 20 percent to 75 percent in property taxes each year. The California Department of Conservation is responsible for the interpretation of the Williamson Act, research of related issues and policies, and enforcement of Williamson Act provisions and restrictions. They have posted frequently asked questions and answers on their website.

The Williamson Act is a means to restrict the uses of agricultural and open space lands to farming and ranching uses during the length of the contract period. It was also envisioned as a way for local governments to integrate the protection of open space and agricultural resources into their overall strategies for planning urban growth patterns. The minimum term for contracts is ten years. However, since the contract term automatically renews on each anniversary date of the contract, the actual term is essentially indefinite.

Farmland Security Zone contracts offer landowners greater property tax reduction. Land restricted by a Farmland Security Zone contract is valued for property assessment purposes at 65% of its Williamson Act valuation or 65% of its Proposition 13 valuation, whichever is lower. The minimum initial term is 20 years. Like a Williamson Act contract, Farmland Security Zone contracts renew annually.

A landowner interested in enrolling land in a contract should contact the Public Works and Planning Department to obtain information and instructions.

There are several ways to tell if a parcel in Fresno County is in the Williamson Act:

  • Look on your tax bill for the breakdown of assessed value. In the box labeled "Land" there will be a notation of "OPEN SPACE" below the value.
  • The annual assessment roll has a column on the far right labeled "Tax Rate Area". Parcels in the Williamson Act will be notated with "OS" under the six-digit code.
  • Parcel maps are notated with "AP" and the Ag Preserve contract number if they are in the Act or "FSZ" if is enrolled in a Farmland Security Zone. If a notice of non-renewal was filed the notation is "NR" and the year the parcel is no longer in the Williamson Act. See our parcel map lookup.
Example parcel map showing notations of property in the Williamson Act
Example Parcel Map showing notations


Affect on the Assessment Roll and Taxes Collected

Graph showing Williamson Act values for the years 1993 through 2023
Williamson Act Values

The graph above shows the assessed value of parcels with Williamson Act contracts. You may see the impact on taxes due in Fresno County by viewing the Impact on Assessed Value spreadsheet(PDF, 157KB) .

Removing a Parcel From the Williamson Act

To end a contract, a "notice of nonrenewal" is filed with Public Works and Planning to start the 9-year nonrenewal period. During the nonrenewal process, the annual tax assessment gradually increases. At the end of the 9-year nonrenewal period (19 years for land in a Farmland Security Zone), the contract is terminated.

A taxpayer may request an immediate cancellation only in extreme and stringent situations, or where the public interest is no longer best served by continuing the contractual restrictions. The landowner may petition the Board of Supervisors or the appropriate City Council for Williamson Act contract cancellation. A notice of non-renewal must also be filed when the cancellation request is made. There is a cancellation fee of 12.5% of the unrestricted, current fair market value of the property in the Williamson Act or 25% if in a Farmland Security Zone.