It’s always interesting to see who, among western municipal water agencies, is considering paying top dollar for the next acre foot of water. Today’s episode comes from Tucson, where Tony Davis explains discussions of turning wastewater into drinking water. The usual “yuck factor” discussion of course is engaged, but the really interesting part to me is the price:
Wastewater recycling is a very expensive, at times controversial, process, costing many times more than the delivery of Central Arizona Project water to Tucson.
It could, for instance, cost anywhere from $1,500 an acre-foot to $3,300 an acre-foot to treat effluent for drinking, the city’s effluent recycling plan says. Pumping CAP water uphill for more than 300 miles from the Colorado River, by contrast, costs $146 an acre-foot for Tucson Water today, and could rise to $157 an acre-foot in 2015.
But as effluent’s use for drinking grows around the arid Southwest, it’s a water supply that many local officials say is inevitable, given the region’s ongoing drought and population growth. They see it as the region’s only sustainable, locally generated water supply, particularly given the strains on the Colorado River due to continued drought.
And as always, it’s important to remember that wastewater almost always isn’t really being “wasted”. It’s already going somewhere, being used for something:
The city of Tucson is entitled to take 21,000 acre-feet of that — enough to serve at least 50,000 homes if the water was drinkable — but it currently takes only about 13,400 acre-feet for turf irrigation or to recharge for future use.
The remaining 11,700 acre-feet of city-owned effluent rolls down the Santa Cruz River — a boon for cottonwood and willow trees that support bird life, to be sure. But Tucson Water’s recycled water master plan sees that differently: “A significant portion of the city’s entitlement left its service area as surface flow after it was discharged to the Santa Cruz River channel without further physical or economic benefit to the city.”