Official Government Website

Modeling Resources

Evapotranspiration and Consumptive Irrigation Water Requirements for Idaho – This University of Idaho website can be used to determine evapotranspiration (ET) and net irrigation requirements (NIR) for crops throughout the state of Idaho.

ESPA Modeling Tools

The ESPA Modeling Tools provide to the water management community a common way to analyze the hydrologic impacts of new water right applications, transfers, and Water Supply Bank rentals within the Eastern Snake Plain Aquifer (ESPA). These tools enable users to evaluate the potential for a proposed transfer within the ESPA to affect flows in the Snake River. In the event that the ESPA Modeling Tools show that the proposal could injure prior rights, the spreadsheets will reveal the extent of the mitigation necessary. The applicant can then draft a mitigation plan which minimizes injury to senior rights and create an application which complies with the ESPA moratorium order. Changes to groundwater use in the ESPA can change the location of depletions in the river and in the tributary springs. An ESPA model analysis is necessary to quantify those depletions so injury to other water rights can be identified and avoided or, if possible, mitigated. This guide is a resource for completing groundwater modeling required for water right transfers in the ESPA.

How to use the ESPA Modeling Tools

  1. Locate and identify your grid cells.
    Use IDWR’s interactive map server to identify ESPA model grid cells for use in the next step.
  2. Run the model.
    The ESPA Model Transfer spreadsheet was designed for individuals with little experience using groundwater modeling software. Download the zipped folder, open the ETransfer spreadsheet, and then add your inputs to the Data Entry tab. Be sure to read the data entry notes in green before running the model. Once you run the model, copy the data at the bottom of the Calculated Effects tab and place the data into the Mitigation Analysis spreadsheet.
  3. Analyze the results.
    The ESPA Mitigation Analysis spreadsheet is compatible with the ESPA Model Transfer spreadsheet. Use the ESPA Mitigation Analysis spreadsheet to analyze depletions to 11 reaches of the Snake River. Compare the model results of your proposal with IDWR’s mitigation threshold values to determine of mitigation will be necessary.
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