Our water table has changed

Our water table has changed.

Irrigation ditches and reservoirs raise the water table throughout Boulder.

Boulder's unconsolidated, rubble-y soil acts like a large sponge and soaks up water from ditches and reservoirs. Ditch companies figure on loosing a third of their water to seepage, and another third to "wetting the ditch".

This water is not "wasted." It recharges the groundwater, feeding deep-rooted trees and wells on its journey back to the creek, a journey that can take months or years.

How are you benefiting from a nearby ditch or reservoir?

  • Do you have a large tree whose roots extend down into the groundwater?
  • Do you use a well?
  • Do you enjoy trails on open space along wooded areas of the plains or along irrigation ditches?

New Mexico State University's Alcalde Sustainable Agriculture Science Center has studied the effect of ditches on groundwater. The graph on the right shows how the Alcalde Ditch directly affects the groundwater level, which rises in the monitoring wells after the ditch is turned on.

7 days after the ditch started, groundwater levels in the Alcalde monitoring wells began to rise. The groundwater levels continued to rise until mid-August when the ditch began to drop, and then generally declined until the onset of the next year's irrigation season.

Right, clockwise from the left:

Many people who live below ditches are familiar with ground-water changes.

Enjoying recreational trails, photo courtesy of Boulder Open Space and Mountain Parks.

Graph of Alcalde Ditch use, Source: Fernald, A.G., T.T. Baker, and S.J. Guldan. 2007. Hydrologic, Riparian, and Agroecosystem Functions of Traditional Acequia Irrigation Systems. Journal of Sustainable Agriculture. 30(2):147-171.

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