Land Evaluation Site Assessment (LESA)


A Land Evaluation and Site Assessment (LESA) is a rating system created by the United States Department of Agriculture Natural Resources Conservation Service (USDA NRCS) to determine whether land is prime for agricultural use.The USDA developed the system in 1981 and released a Site Assessment Handbook in 1983 as a model for counties to use to preserve agricultural land. On October 21, 1985, Story County adopted its own LESA system. 

Agricultural land is a finite resource that is necessary for the production of food in Story County, Iowa, and across the world. The LESA system impartially determines the value of agricultural land and is used in Story County to maintain high-value agricultural land in agricultural production. Specifically, in Story County, a score is assigned to a property through a LESA to determine if it qualifies for an exemption to the 35-acre minimum lot size required for dwellings in the A-1 Agricultural Zoning District and to allow rezonings to non-agricultural zoning districts and certain conditional use permits. 

As part of its 2019 work program, Story County Planning and Development Department was tasked with the review and update of the LESA system. From the review, the Department found that LESA continues to be a valuable method for identifying prime agricultural land. As part of the review, the Planning and Development Department is working to provide more information and increase understanding of how a LESA Score is conducted.


Introduction to Story County’s LESA System

LESA is a point system that evaluates a site’s suitability for agricultural use in relation to soil productivity and locational, economic, and governmental factors. LESA consists of two parts:

Part 1: Land Evaluation

The land evaluation (LE) rates a property’s soil productivity for use as cropland. Point values are assigned to each soil group present on a site based on a range from 0-100. The values are based on USDA NRCS Soil Survey data and Crop Suitability Rating (CSR). A weighted average of the values is calculated for a site on a range between 0-100 points. For most properties in Story County, the LE score is calculated by an automated script that uses the CSR data and parcel boundary data in a Geographic Information System (GIS) to determine a score for each parcel. 

Part 2: Site Assessment 

The site assessment (SA) accounts for additional factors, such as surrounding land use, which can contribute to the quality of a site for agricultural use or compatibility with non-agricultural development. Points for a variety of factors are assigned and summed to calculate a site’s SA value, which may range between 0-200 points. A maximum total score of 300 points is possible when combining the LE and SA scores to determine the overall LESA score. The higher the point value a site receives, the may be better suited a site is for agricultural use. 

To learn more about the scoring process and the factors considered, a sample LESA score worksheet with explanations of the factors and instructions is available here

How A LESA Score is Used

It is the intent of Story County’s LESA system that land with a high LESA score is encouraged to remain in agricultural use. Non-agricultural development is strongly discouraged for sites with high LESA scores.  

A-1 Agricultural Zoning District

If the parcel is evaluated by LESA and identified as being low-to-moderate value agricultural land for both the site assessment (SA) score and the total LESA score, as defined in Table 86-1 (see below), a minimum lot size of one acre (net) for single-family dwellings may be permitted in the A-1 Agricultural District (when property is located within the Ames Fringe Area Plan, this exception only applies if the property is designated Agricultural and Farm Service). Typically, a 35 net-acre minimum lot size is required. 

Table 86-1

SA ScoreLESA ScoreMinimum Lot Area
0-1720-266One net-acre 

Conditional Uses

It is not intended to permit certain uses in the A-1 District where the LESA score for the subject parcel is 267-300. Refer to Table 90-1 – Table of Conditional Uses for specific information on impacted uses. 


In areas where the petition to rezone requests a change from A-1 Agricultural District or A-2 Agribusiness District to another district, lands scoring 267 or above for total LESA score shall not be approved. Further, It may be necessary to rezone land scoring 267-300 points based on the Land Evaluation and Site Assessment (LESA ) System to A-2 Agribusiness, although this shall be avoided where possible. 

Kelcy Gatson