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Colorado's public lands are faced with new challenges but water and land management depend on working together. Read about the relationship between water and land in Colorado and how Coloradans are converging to restore Colorado's public lands in the Spring 2018 issue of Headwaters magazine.

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Water Education Colorado

San Luis Valley Waits for Judicial Ruling and Mother Nature

By Ruth Heide

San Luis Valley residents are waiting and hoping.

They are waiting for a decision from District Judge O. John Kuenhold regarding proposed state rules governing new groundwater withdrawals in the Rio Grande Basin.

And they are hoping—for moisture.

Court Ruling May Take Time
No deadline is set for a ruling in the Colorado Division of Water Resources' San Luis Valley confined aquifer rules case. The nearly six-week trial was argued by a dozen attorneys earlier this year.

At issue is how much water, if any, is available to pump from the deep aquifers underlying the valley. And, if that water is pumped, how much should be returned to the system to prevent exhaustion of the aquifers over time.

Attorneys presented final arguments to the judge on March 24. Kuenhold gave each side until the first of May to file proposed findings of fact and conclusions of law, and he has since granted several extensions. The judge has not set a deadline for his own decision in the case. ‘It will take some time,’ he says.

The issue started building when the Colorado General Assembly passed House Bill 1011 in 1998 and Senate Bill 222 in 2004, recognizing the valley's unique hydrology, the need to protect existing water rights and the state's Rio Grande Compact delivery obligations to downstream states.

In response, Colorado Division of Water Resources State Engineer Hal Simpson promulgated rules on June 30, 2004, governing new groundwater withdrawals from the valley.

Arguing in favor of the state's rules at trial were attorneys from the Attorney General's office, Rio Grande Water Conservation District, Conejos Water Conservancy District and Rio Grande Water Users Association.
Objectors were led by attorneys representing Cotton Creek Circles, San Luis Valley Water Company and Colorado Association of Home Builders.

The proposed rules govern new groundwater withdrawals from the confined or deep aquifer system in the San Luis Valley. The rules are premised on the state engineer's conclusion that the Rio Grande Basin is over appropriated and new groundwater withdrawals will be detrimental to senior water rights and Rio Grande Compact deliveries.

Under the proposed rules, any new groundwater withdrawals should not cause fluctuations in the artesian pressure greater than the ranges which occurred between 1978-2000, a relatively stable period for the aquifer. Well pumping will only be permitted if an existing surface or groundwater water right equal to the amount requested is permanently retired or diverted. In other words, someone wanting to drill a new well under these rules would have to take an existing well out of production.

Rio Grande Water Conservation District Manager Steve Vandiver, RGWCD engineer Allen Davey, and hydro-geology expert James Slattery testified during the confined aquifer rules trial that the valley's water supply is overappropriated and the current level of groundwater use unsustainable.

Davey testified his studies reveal a long-term decline in the San Luis Valley's confined aquifer. Hydrologist Charles Brendecke testified that the aquifer declined at an average rate of 58,387 acre-feet per year from 1970 to 2002.
Peter Ampe, the attorney general's lead counsel, told Judge Kuenhold that Senate Bill 222 was enacted because the San Luis Valley aquifer systems are unique.

Like a great bowl, over geologic time, the San Luis Valley accumulated thousands of feet of what are called basin-fill deposits. The deposits form the valley's aquifer system.

In the northern portion of the basin, all streams flow into a closed basin, an internal drainage encompassing approximately two-thirds of the valley. In this area, streams such as the La Garita, Carnero, Saguache and San Luis flow into the closed basin and do not have a natural outlet to the Rio Grande.

Five main geological layers exist beneath the valley's surface, explained William Schreüder, the state's computer modeler. The unconfined or shallow aquifer lies in the first layer. Beneath a blue clay layer, which may be hundreds of feet thick in some places, are the deeper layers that make up the confined aquifer.

Attorneys protesting the rules argued that the San Luis Valley is not geologically or hydrologically unique; and the rules interfere with individuals' constitutional rights to appropriate water. They said that the rules are unnecessary because an ample supply of water is available. They argued the Rio Grande Basin inflow of 1.15 million acre-feet from precipitation and irrigation seepage greatly exceeds total pumping of 640,000 acre feet, and therefore the aquifer is not in danger.

Steven Bushong, one of the objectors' attorneys, told the judge the San Luis Valley's confined aquifer contains an estimated 1 billion acre-feet of water. If that is the case, he argued, the 1.5 million acre foot loss in the aquifer recorded by Davey in the last 30 years would still leave 99.8 percent of the water.

The objectors' computer modeling witness Bill Hahn said the effect of new withdrawals of 10,000 acre-feet per year over 100 years would be minimal.

Objectors' expert witness Bruce Lytle testified water can be appropriated in the confined aquifer without replacing 100 percent of new withdrawals if standard plans for augmentation are prepared to ensure sufficient water is available to fulfill senior surface water rights, or out-of-priority depletions.

The state plans to administer its proposed rules using the Rio Grande Decision Support System, a complex computer model developed under the authority of House Bill 1011 approved in 1998. The validity and accuracy of the RGDSS model was extensively argued throughout the six-week trial.

Hahn and expert hydrogeology witness Charles Norris testified the RGDSS is unreliable, poorly calibrated and unacceptable for predictive purposes.

Schreüder, who was responsible for developing the RGDSS and spent four days at trial defending it, testified the model is accurate and reliable for predictive purposes and can evaluate impacts of new withdrawals from the confined aquifer.

When Judge Kuenhold makes a decision, he may approve the state's proposed rules, modify them or send them back to the drawing board.

The Local Approach
Chief Deputy State Engineer Ken Knox testified the state will likely also develop rules for the valley's shallow or unconfined aquifers in the future. But, he testified, the state is first trying to work with irrigators.

The idea is to create groundwater management subdistricts to enable irrigators to reduce groundwater use in an organized manner, without state interference, while protecting senior water rights and other obligations. Landowners within the subdistricts may agree to fallow a certain amount of land.

Farmers who voluntarily take land out of production are then compensated by programs such as the federal Conservation Reserve Enhancement Program. In the end, this will help replenish the shallow aquifers, and protect those who have surface water rights.

Vandiver says five San Luis Valley subdistricts are currently in one phase or another of development. To be included, a simple majority of subdistrict landowners must sign petitions and present them to the Rio Grande Water Conservation District, the state engineer and the water court for approval.

Landowners participating in the Groundwater Management Sub-District #1, the closed basin sub-district, account for some 134,000 acres of farmland. Groundwater Management Sub-District #2, which is on its way to water court for approval, will encompass approximately 30,000 acres in the unconfined aquifer south of the Rio Grande.

Still in the process of collecting landowner petitions is the Conejos Special District No. 1, a sub-district within the Conejos Water Conservancy District's boundaries. Two additional subdistricts are still in their infancy: 1) a Saguache Creek drainage sub-district led by the Saguache Creek Well Owners; and 2) a subdistrict in an area between the Monte Vista and Alamosa Wildlife Refuges and between the Stanley Road on the north and Conejos Water Conservancy District on the south.

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