Irrigation and Water Management Survey

The target population for the Irrigation and Water Management Survey was composed of all farms irrigating in the reference year. From the Census of Agriculture, records are identified as belonging to the general U.S. irrigation population on the basis of having irrigation activity on their farm or ranch. The target population was expanded to include any operations that had irrigated land in the past five years. Institutional, research, and experimental farms were excluded from the total number of irrigators that reported in the census.

The sample was drawn at a State level for all 50 States. This sample design targeted a U.S. level sample size of 35,000. A certainty stratum, with farms selected with probability one, was included for each State to ensure that the major irrigators in each State were sampled. The remaining strata were sampled systematically by irrigated acreage. The stratification boundaries varied among the States and were dependent on the distribution of total acres irrigated within the State. The stratified design ensured that the sample was reflective of the survey population and achieved the appropriate coefficients of variation (CV) levels at both the U.S. and State levels.

Linking at an operation level over time cannot be accomplished using the Irrigation and Water Management Survey data due to the methodology used to sample the survey. E.g. the 2023 IWMS data cannot be linked to the 2018 IWMS data by operation. Operations responding to the Irrigation and Water Management Survey in one survey year can be linked to the Census of Agriculture data from the same Census cycle (e.g. the 2023 IWMS data can be linked to the 2022 Census of Agriculture data by operation). Linking IWMS data and Census data within the same Census cycle will result in many records that will not have a match due to reasons such as nonresponse and changes in operations.