In his May 2 Guest Opinion, Roger Batt, director of the Treasure Valley Water Users Association, worries that the Bureau of Reclamation, by releasing water from the three Boise River reservoirs to limit flooding, may overdo it and leave the Valley short of irrigation water in late summer. Anyone inclined to share Batt’s anxiety should wait a month or so. The safe bet is that there will be more than enough irrigation water in the reservoirs this year.
History shows that when the federal government releases water for flood control — which happens only in wet years — reservoirs end up about 98 percent full on average. This is better than dry years when there are no flood control releases and, on average, the reservoirs end up about 73 percent full.
If the problem in a wet year like 2017 is not a lack of water, what is the issue? It’s that Batt’s irrigation districts believe the federal government should have discretion to fill the reservoirs not just once each year, but twice, even if this takes water from other water right holders. They are unhappy that the Idaho Department of Water Resources allows the feds a “second fill” only if doing so causes no harm to other Idaho water rights. For decades, the department has followed this principle and irrigators have always ended up with all the water they needed in flood control years.
A more productive discussion about the Valley’s water future focuses not on flood release policy, but on the billions of gallons of river water the irrigation entities still allocate to non-irrigated areas such as shopping centers, offices, parking lots, streets, patios and rooftops. An April 23 Statesman article reported that Boise State University professor Jodi Brandt found that 156 square miles of farmland (about 100,000 irrigated acres) “were lost in Ada County from 1974 to 2012.” That seems a shocking number — and it doesn’t even include the Canyon County figures or urbanization since 2012 — until one reflects on our Valley’s prodigious growth.
Urbanization means overall irrigated acreage, and thus demand for irrigation water, is shrinking in our Valley. Yet, irrigators continue to divert Boise River water as if ag-to-urban development had not occurred.
I don’t think anyone has studied where the diverted but unused water goes, but much of it must be flowing out of state. To some, the loss of large amounts of irrigated farmland may seem short-sighted, even if it is driven by free market forces. But the diversion of surplus irrigation water to non-use should be even more troubling.
This practice makes it difficult for communities to implement water-wise policies, it probably pollutes the river with heat and contaminants, it keeps us from moving water to other uses, and it could prevent us from recapturing this water in the future. Diverting unused water in Idaho may be a windfall for the new agricultural and commercial development occurring in Oregon and Washington, but it should be a source of actual worry in our state.
Mark Hill, of Boise, is an aquatic ecologist with 40 years of consulting experience on water issues throughout the West and internationally.