Managed Recharge
Trend or anomaly, fact or fiction?
It’s a fact that the global temperature has been on the rise, according to the Goddard Institute for Space Studies (GISS). Nine of the 10 warmest years have occurred in the 21st century with 2011 as the ninth warmest in the GISS analysis.
It’s also a fact that the finite limitations of surface water has forced water users to seek other hydrologic solutions. Tapping into subsurface aquifers has been the answer but now the aquifers are showing the stress and fatigue from too many users depleting nature’s underground storage system.
Now, combine a trend line of warming temperatures with the National Weather Service’s prediction that the U.S. seasonal drought outlook will persist or intensify throughout the Great Plains and the Intermountain West into 2013 and water conservation becomes increasingly important.
Water resource management has come to the forefront in the water wars being waged throughout the Intermountain West. One possible means to alleviate the diminishing pool of water available is managed recharge of aquifer systems.
David Tuthill, founder of Idaho Water Engineering, LLC. and a former director of the Idaho Department of Water Resources, is a vocal proponent for managed recharge in Idaho and an advocate for private funding of new water projects.
Rising temperatures translate into an earlier spring thaw in Idaho, resulting in snowpack melting earlier and storage reservoirs filling to capacity earlier in the season in the Upper Snake River.
According to Tuthill more than a million acre feet, on average, flow downstream over the Milner Dam during the spring runoffs in Idaho. That’s a million acre feet that Tuthill believes could be put to better use upstream recharging the Eastern Snake River Aquifer.
The amount of water going over Milner is unbelievable.” Tuthill said, “The opportunity for recharge is unbelievable.”
“There are two opportunities for managed recharge,” Tuthill said. “One is in existing canals and the other is in addition to that through new canals.”
In years when snowpack is ample, Tuthill would like to see canals open up a month early for the sole purpose of managed recharge of the aquifer.
“I see the managed recharged aquifer as additional to surface reservoirs,” Tuthill said. “We’re moving beyond just conjective administration, which is the delivery of water. We’re moving beyond to conjective management, which is optimal management of our water system.”
Tuthill is representing Recharge Alliance, a group of water providers made up of irrigation districts and canal companies. In the fall of 2011 the Recharge Alliance released 30,000 acre feet in a managed recharge into the Eastern Snake River Aquifer. According to Tuthill some of the recharge bleeds out downstream but based on a calibrated computer model the water providers still have 14,000 acre feet in the aquifer.
An additional benefit from aquifer recharge is water is not lost through evapotranspiration as happens to surface water storage systems.
Tuthill envisions the use of managed recharge to serve as mitigation for future appropriations of the aquifer and to avoid curtailment of water rights in the future.
Tuthill employs the term “additionality” in the course of discussing managed recharge. Additionality is a notational measurement of an intervention, when the intervention is compared to a baseline and doing something different, something additional to what’s been done in the past.
“So we’re using this term, this concept of additionality, to provide additional aquifer recharge, managed recharge that will enable, we think, those in the Eastern Snake River Aquifer to move forward with development,” Tuthill said.
The best time for managed recharge of the aquifer is during the spring flows but the current canal systems cannot handle the million acre feet and more that flows over the Milner Dam in good snowpack years.
That is why Tuthill would like to see a large canal that diverts springtime high flows into the desert to percolate into the Eastern Snake River Aquifer.
Tuthill doesn’t see state funding for this water project being appropriated anytime soon but that’s not to say private investors might not come in and build a diversion canal for managed recharge.
“In the future we’re moving towards less plenty so we have to be more careful managers of the resource,” Tuthill said. “The value of water in Idaho is increasing to a point where it makes it affordable to better manage the water.”
