Two Years In, Drinking Water Project Delivers on Promises

Designed to preserve the Albuquerque area’s underground aquifer by employing renewable surface water as a drinking water source, the San Juan-Chama Drinking Water Project has produced some 20 billion gallons for the people of Albuquerque and Bernalillo County since operations began in late 2008. Today, more than 40 percent of the metro area’s water supply is provided by the San-Juan Chama Drinking Water Project.

The Surface Water Treatment Plant

Quality

Surface water must undergo a much more extensive treatment process than groundwater before it is safe to drink. The multistage purification process, which employs carbon filtration and ozone disinfection, has yielded excellent results in terms of water quality the first two years.

“All the water water produced by the Drinking Water Project has either met or exceeded the state and federal standards for clean drinking water,” said John Stomp, Chief Operating Officer for the Water Authority.  “Process testing occurs on an ongoing basis at our water treatment plant to ensure that quality requirements are met at all times.”

Unlike the groundwater in the Albuquerque area, the surface water contains little to no arsenic. By blending San Juan-Chama with groundwater, the Water Authority was able to bring its entire service area into earlier-than-required compliance with new federal arsenic standards.

Finally, the project has resulted in improved water quality downstream from Albuquerque, as surface water returned to the river after passing through the system is lower not only in arsenic but in total dissolved solids and radioactive trace elements known as radionuclides.

“This means a cleaner river for downstream irrigators, communities and wildlife species,” Stomp said.

Regulatory Compliance

Our use of San Juan-Chama water is closely monitored and regulated by the Office of the State Engineer, which requires the Water Authority to cease diverting San Juan-Chama water from the Rio Grande during periods of low river flows. The permit governing our use of the water also requires that native Rio Grande “carry” water (diverted from the river to enable full use of the San Juan-Chama water) be returned to the river downstream simultaneously with the diversions.  This way there is no net loss of native water downstream.

“San Juan-Chama water is diverted into the Rio Grande through a system of channels, tunnels and reservoirs,” Stomp explained. “As a community, we have purchased perpetual rights to that water. But we are careful to use only what belongs to us, and to return all native Rio Grande water to the river.”

In all, there are more than 18 permit conditions for the Water Authority’s use of San Juan-Chama water, and in the first two years of operation the Water Authority met or exceeded all of the stringent requirements placed on it by the state.  These include informing the State Engineer in advance of diversions and monitoring the amount of water in the Rio Grande prior to and just after the diversion and downstream of the wastewater return.

“The rate of flow in the river between the diversion point and the outfall of the wastewater treatment facility must be at least 122 cubic feet per second,” Stomp said.  “We plan and report our diversions in advance, and can curtail them if necessary, to ensure that everyone and everything that depends on the Rio Grande can continue to count on it as a resource and as a habitat.”

So far, he added, no curtailments have been necessary on the Water Authority’s part to maintain minimum flow requirements in the river.

San Juan-Chama water is diverted from the Rio Grande using an adjustable dam.  All diversions are planned and reported in advance to the Office of the State Engineer and can be curtailed if necessary to ensure sufficient river flows.

Aquifer Preservation and Recovery

Every gallon of San Juan-Chama water used is a gallon that doesn’t get pumped from our aquifer. Unlike the aquifer, which takes many years to recharge after being pumped, imported San Juan-Chama water is a renewable resource that originates as yearly snow-melt in the mountains of southern Colorado. 

“It makes sense to use this resource while keeping the aquifer as a drought reserve for those years when snowfall is not adequate to meet our needs,” said Art De La Cruz, Chair of the Water Authority Board. “Reducing our reliance on the aquifer also reduces the likelihood of soil sinkage due to over-pumping.”

The assurance of having an intact and healthy aquifer contributes to economic growth and stability (a $2 billion benefit, according to some estimates) and will mean water security for our children and grandchildren.  And after just two years of surface-water use, the aquifer is showing signs of recovery.

“In our observation wells monitoring the aquifer’s primary production zone on the east side of the Rio Grande, we are observing increases in the winter water levels, which are most representative of the condition of the aquifer,” said Doug McAda, Groundwater Specialist for the U.S. Geological Survey New Mexico Water Science Center, which monitors and studies the aquifer in partnership with the Water Authority. “This is consistent with the trends in water levels from our model simulations of reducing groundwater pumping in favor of using surface water.”

The increases in groundwater levels are a few feet at most, and vary from location to location. John Stomp of the Water Authority said any improvement at all is encouraging.

“The water-level trend had generally been downward through the early part of the decade,” he said. “To see that begin to reverse is a very positive development.”

Projections based on USGS model simulations indicate that continued use of San Juan-Chama water over the next 40 years could result in aquifer levels increasing by as much as 50 feet in the areas most impacted by pumping.

 Model simulations show the aquifer recovering over time as a result of reducted pumping

USGS Aquifer Recovery Model [520KB pdf]