Daily Calculator

The Nerds Water Needs Calculator is specific to lawn irrigation in Kootenai and Spokane counties. Calculations are based on weather information collected at Agrimet stations in the region and averaged for the years 2015, 2016, 2018, 2019, 2020, and 2021. Evapotranspiration rate and growth stages of the crop (crop coefficients) are the key data used to calculate the average water needed for lawns (turf grass) from April 1 to September 30. It’s not necessary to water your lawn outside of those dates.

Soils may vary in appearance but in general the hydraulic properties are very similar throughout the region. For the Nerds Water Need Calculator we considered soils to be gravelly ashy loam.  This soil type is comprised of gravels of various sizes in a matrix of volcanic debris and organic bearing fine silt, with and without clays.