The California Agricultural Land Evaluation and Site Assessment Model (LESA Manual) developed by the California Department of Conservation in 1997 and the Soil Survey, California published by the US Department of Agriculture, Soil Conservation Service (now the Natural Resources Conservation Service) in 1971.


In 1981, the federal Natural Resources Conservation Service (NRCS) known then as the Soil Conservation, released a system designed to provide a quantitative method or rating the agricultural suitability of land compared to demands for non-agricultural uses of lands.  This system became know as the Land Evaluation and Site Assessment  (LESA).  LESA and adopted as a procedural tool at the federal level for identifying and addressing the potential adverse effects of federal programs on farmland protection.  The formation of a California LESA Model is the result of legislation adding Section 21095 to the California Environmental Quality Act (Chapter 812, Statues of 1993).  This section directed the Resources Agency, in consultation with the California Office of Planning and Research to amend Appendix G of the CEQ Guidelines to “provide lead agencies an optional methodology to ensure that significant effects on the environment of agricultural land conversions are quantitatively and consistently considered in the environment review process.”  Section 21095 also required the California Department of Conservation to develop a state model land evaluation and site assessment system, which in turn could be adopted by the Resources Agency as its amendment to Appendix G.


In 1997, the California Department of Conservation published the California Agricultural Land Evaluation and Site Assessment Model.  Appendix G of the CEQ Guidelines, as revised in October 1998, includes the provision that “In determining whether impacts to agricultural resources are significant environmental effects, lead agencies may refer to the California Agricultural Land Evaluation and Site Assessment Model 1997 prepared by the California Department Conservation as an optional model to use in assessing impacts on agriculture and farmland.  The LESA model is useful to CEQ studies because it utilized several basic factors, which can capture much of the variability associated with the determination of the relative value of agriculture lands.


The LESA model uses a point-based approach to rate various factors related to agricultural characteristics that ultimately result with an overall score for the project wide.  This final LESA model score is a tool used by lead agencies to determine whether the conversion of farmland on a project site could be considered a significant impact.


The LESA model breaks project site factors related to agricultural suitability into two categories:  land evaluation factors and site assessment factors.  Two land evaluation factors measure inherent soil based qualities of the project site as they relate to agricultural suitability.  Four site assessment factors measure the social, economic, and geographic attributes as the relate or contribute to the overall agricultural value of the project site.  A separate score is determined for each factor.


The six factor scores generated from the land evaluation and site assessment evaluations are recorded on a final score sheet.  The six final scores are the weighted, summed and used to generate a single LESA score for a project site is used to determine the significance of the proposed conversion of agricultural land to non-agricultural use.


According the California Department of Conservation, the LESA model is designed to make determination of the potential significance of a project’s conversion of agricultural lands to non-agricultural used during the CEQA review process.  The scoring thresholds are based upon the total LESA score a swell as the component land calculation and site assessment sub scores.  The scoring thresholds are depend upon the attainment of a minimum score for the land evaluation and site assessment sub scores so that a single threshold is not re result of heavily skewed sub scores (i.e. a site with a very high land evaluation score, but a very low site assessment score, or vise versa).