A four-mile reach of the Gila River runs dry sometimes in hot summer months when irrigators divert water to irrigate pasture for cow-calf operations. Five native fish, two of which are rare and protected, can’t live without water and populations have declined.
One proposed solution to this problem is to build a $300 million dollar reservoir at taxpayers’ expense that would irreparably harm river health but could in theory release some water back to the river in dry months.
Stated another way, this solution proposes to kill a river to try to save a fish.
This plan is the latest justification pitched by the New Mexico Interstate Stream Commission for building the New Mexico Unit, a federal water project under the Arizona Water Settlements Act. The project would double current water withdrawals from the river for water supply, altering the natural flow of the Gila River, New Mexico’s last major, free-flowing river.
The variety of flows in a natural flowing river, like the undammed Gila, sustain the entire river ecosystem. Low flows provide adequate oxygen to fish, sustain the shallow groundwater table for vegetation and support insects that feed on material carried downstream.
Flood flows recharge the groundwater table, rewet wetlands, renew fish spawning habitat, germinate native riparian seeds and provide environmental cues to aquatic and other life to complete their life cycle, nest or spawn.
The proposed New Mexico Unit would take water from small and moderate floods and store it in a reservoir to release later to supplement the river in drier months.
While in theory this might sound like a good idea, it does little to protect native fish that rely on flood flows to increase food supply and improve spawning habitat. We would be robbing Peter to pay Paul by essentially trading beneficial flood flows to increase low flows to the detriment of fish and other plants and wildlife that make up the river ecosystem.
These impacts of lower habitat quality from the proposed diversion and reservoir would not just affect fish; the same story could be told for riparian and bird habitat and has been chronicled time and time again on rivers with federal dams and other infrastructure across the West.
This is not inconsequential for New Mexico’s last major, natural, free-flowing river which is currently renowned for one of the highest concentrations of breeding birds in the entire nation, the largest contiguous stretch of multi-aged cottonwood-willow forest remaining in New Mexico, and multiple fish and wildlife that reside on the endangered species list.
Someone, most likely taxpayers, will have to pay the cost of environmental mitigation if the New Mexico Unit is built.
But environmental impacts from the proposed New Mexico Unit are just one of the many bills New Mexicans will pay to build it to supply water to New Mexico. The other bill is the cost of constructing and operating the New Mexico Unit.
Yes, there is a federal subsidy, but it is unlikely to cover more than one-third of the costs. Two-thirds or more of the bill – estimated in the hundreds of millions of dollars – will likely be picked up by taxpayers or the end user whether water utility ratepayers or irrigators.
Local residents and water users within the Gila River, San Francisco and Mimbres River basins have identified cheaper, easier and more environmentally sustainable solutions to secure Southwestern New Mexico’s water supply than a federal diversion, reservoir and pipeline; solutions like water conservation, irrigation efficiency, effluent reuse, sustainable groundwater management and watershed restoration.
If New Mexico were to implement these non-diversion projects they could fill the gap, providing more water for a third of the cost. Federal funds are available to build these non-diversion water supply projects, create jobs and supply water at no additional expense to New Mexicans.
It is not too late. Non-diversion alternatives are currently being evaluated by the Interstate Stream Commission. If we select the non-diversion alternatives, we can do a better job protecting the fish, the Gila River and New Mexico’s water supply for future generations.