Judge approves well rules for R.G. Basin

ALAMOSA — Groundwater rules are officially in effect in the Rio Grande Basin.
Water Judge/Chief District Judge Pattie Swift on Friday approved groundwater rules that had been filed by the State Engineer in September 2015 and had been pending protests, which resulted in a trial to the court early last year. Judge Swift denied the protests and ordered that the rules be approved as filed with the court, effective immediately.
The rules govern the withdrawal of groundwater in Water Division 3 (the Rio Grande Basin/San Luis Valley) and set the criteria for the beginning and ending of the irrigation season for all irrigation water rights. The presumptive irrigation season is April 1 to November 1.
All non-exempt well users in the Valley are now subject to these rules.
Judge Swift in her March 15 ruling determined that the rules complied with statutory standards governing rules and regulations for groundwater withdrawals and establishment of the irrigation season.
After the State Engineer filed the rules in 2015, several organizations filed official statements in support of the rules, and several individuals or groups also filed statements of opposition protesting the rules.
The State Engineer subsequently reached stipulations with most of the protestors short of trial. Several stipulations acknowledged that refinement of the groundwater model was an ongoing process and the state would continue gathering and incorporating additional data to refine the model. The model is used to calculate stream depletions caused by groundwater withdrawals.
The court held a trial on the remaining protests from January 13 to February 14, 2018.
Remaining objectors included 2J Ranches Group, James Warner, Kelly Sowards and Karen and Colin Henderson, who testified during the trial.
Experts testifying on behalf of the rules included Division Engineer Craig Cotton, Eric Harmon, James Slattery, Assistant Division Engineer James Heath, Willem Schreu?der, Ph.D. and Deputy State Engineer Mike Sullivan. State Engineer Kevin Rein also testified. Expert witness on behalf of the protestors was Gregory Sullivan.
The court considered nearly 200 exhibits as well as testimony and arguments.
One of the 2J Group’s main objections to the rules was the use of the groundwater model, which they argued was not reliable at least in measuring the depletions they had suffered to their senior water surface rights as a result of well pumping. They argued that the model was not calibrated to Arroya/Diamond Springs or La Jara Arroya Creek, which they maintained had been essentially dried up as a result of well pumping. The State Engineer agreed the model had not been calibrated to these springs because there was not enough data to do so, and 2J argued that then there was not sufficient data to promulgate the rules because they failed to establish replacement requirements for groundwater depletions at those springs.
The state and division engineer have argued that well pumping is not the only reason for the diminished flow at Arroya/Diamond Springs, and the judge agreed. (For example, reduced precipitation in the Valley and changes in farming practices have contributed to the decline, the judge noted.)
The judge stated that it was a lack of reliable data, “not a lack of reliability of the model” that was the reason the model could not reliably predict depletions to Arroya/Diamond Springs. When more data is available — and the State Engineer is working on obtaining more data for this area — it will help the State Engineer determine how groundwater withdrawals are affecting the flows of the springs, the judge stated.
The judge stated that most of the rules were not challenged by anyone at the trial, and the burden to prove the rules invalid rested with anyone challenging them.
Judge Swift recounted the history leading up to the rules, namely that the aquifers in the basin were over appropriated and that the State Engineer had the right to adopt rules to administer groundwater and surface water in the basin in a way that protects senior water rights “with the minimum impact on existing vested groundwater rights.”
She also talked about the process the state went through to develop the current groundwater rules and the development of the Rio Grande Decision Support System, the groundwater model used to determine injurious groundwater depletions to surface water rights, which must be replaced. The court previously and again in this ruling agreed that the model was necessary and appropriate for that purpose.
In her ruling Judge Swift spoke extensively about how the model has been developed and refined, how it operates, how new information has been incorporated into it and how it will continue to be improved in the future. Some of those improvements are part of stipulations with protestors to the rules.
More than 50 pages of the 150-page ruling dealt with the model and “response functions,” a “simplified form of the output from the RGDSS Model” that can be used to calibrate stream depletions without running the entire model.
“The Division of Water Resources (“DWR”) is constantly improving the reliability of the data sets used in the RGDSS Model by improving the reliability of data collection, data processing, and data estimation and DWR is constantly improving the software packages used in the Model. Ultimately, all of this work improves the overall reliability of the RGDSS Model,” the judge stated.
She added, “no groundwater model is perfect and all can be refined and improved, but that does not mean the model is not an appropriate tool or cannot be used appropriately.”
The judge added, “The fact that the State Engineer and the modelers do not have all of the answers and have not been able to create a perfect groundwater model for Water Division No. 3 is not a reason for this court to disapprove the rules.”
She said when the State Engineer has more reliable information, specifically regarding Arroya/Diamond Springs, that information will be used to develop response functions for that area.
The judge stated that 2J Group had failed to carry its burden of proof regarding the rules’ validity.


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