Open Space Subvention Act

The Open Space Subvention Act (OSSA) was enacted on January 1, 1972, to provide for the partial replacement of local property tax revenue foregone as a result of participation in the Land Conservation (Williamson) Act and other enforceable open space restriction programs (Government Code §16140 et seq.). Participating local governments have received annual payment on the basis of the number of eligible acres, quality (soil type and agricultural productivity), and, for Farmland Security Zone contracts, location (proximity to a city) of land enrolled under eligible enforceable open space restrictions.

Open Space Subvention Payments

Open Space Subvention payments totaled more than $863 million between 1972 and 2010.  Despite elimination of OSSA payments since the FY 09/10 budget, information provided by counties and cities is critical in order to document the level of participation in the program and the impact the loss of OSSA payments is having on local governments.  It is the basis for the biennial Land Conservation Act Status Report, which provides information to the Legislature and general public on the status of the Program among counties and cities. ​Statistics are available in Appendix B of the 2016 Williamson Act Status Report.
The Department of Conservation continues to work with assessor offices and planning departments to document participation in the Land Conservation Act through the Open Space Survey of Participation.

Open Space Subvention Act Survey​ - Now Available

The 2019 Survey of Participation in the Land Conservation Act and Open Space Subvention Act (OSSA) forms are now available.  They have been posted in two formats, for your convenience​:​

The 2019 Survey in XLS format or the 2019 Survey in XLSM format​​.

Also, please note the mapping and additional reporting requirements associated with this process (PDF).  

Please see the instructions for completing and submitting forms and the recently added 2019 Survey of Participation FAQs​ handout for additional help.

Annual Survey of Participation forms are due to the Department of Conservation by October 31, 2019.   

If you have any questions or problems with the survey form, please contact Farl Grundy, Environmental Planner, at (916) 324-7347.  Or contact us via email at   

Thank you in advance for your assistance.  ​​​​