Aquifer at risk with district's proposed augmentation plan

By Valda Terauds, San Isabel Hydrologist

In response to the Upper Arkansas Water Conservancy District’s proposed augmentation plan, I submit that the community’s problem with this plan is not a “lack of understanding.” The problem is that the plan does not include protecting the local aquifer that provides water to many rural residents in the Wet Mountain Valley.

 The district’s plan is only concerned with protecting senior surface water rights; it does not “move water to wells.” It would facilitate increased groundwater extraction by augmented wells without providing a means for aquifer recharge or a means to address injury to local groundwater users, who may only have a well permit and not a decreed water right.

I suggest explicitly excluding exempt (e.g., domestic) wells from the augmentation plan and limiting groundwater structures eligible for augmentation to non-exempt wells and structures with decreed groundwater rights.

The concerted efforts of Custer County commissioners and residents from 2009 to 2011 defeated a similar augmentation plan. It is not clear why this second attempt at an augmentation plan is being made now. It has been stated that the district knew there would be local opposition and so was not interested in pro-actively working with Custer County to develop a plan that reflects our concerns.

The proposed plan will facilitate expanded pumping of wells in a shared aquifer. Existing, unaugmented exempt wells (limited to 15 gallons per minute) may experience excessive drawdown, a need to deepen pump settings or drill deeper wells as the local aquifer is affected by new augmented pumping. The burden of proof that no harm will come to existing water users lies with the district – until the plan is approved by the Water Court.

Once the plan is in place, the individual well owner has no relief through this augmentation plan and no standing in Water Court because well permits are not decreed water rights subject to priority administration. The burden of proof for injury will lie with the individual well owner, and it is unlikely the division engineer will offer tangible remedies, other than “drill deeper,” thanks to the expanded “augmented” pumping by your newor now full-timeneighbors.

To put some numbers on this issue, Colorado water planners typically estimate household indoor water use at 0.4 to 0.5 acre-feet per year. With augmentation, pumping by a domestic well could potentially be expanded to 24 acre-feet per year per augmented well (if the allowed 15 gallons per minute pumping rate is sustained year-round to support an irrigation allowance of 1 acre). Assuming a four- or five-month irrigation season, the increased potential pumping of about 10 acre-feet per year is still significant compared to indoor use only.

Without active groundwater management, our shared aquifer will continue to be drawn down without regard for recharge or long-term sustainability. Hydrologic studies are sorely needed in this valley to avoid arbitrary blue lines (like those on the augmentation plan map) that have no connection to geologic realities. Before a blanket plan is proposed for Custer County, a comprehensive basin study should be undertaken to understand the aquifer storage. It should include yield; aquifer-stream interactions; the margins of the alluvial and fractured aquifer systems; the basic aquifer characteristics of hydraulic conductivity, gradient, transmissivity; and valley circulation systems. 

A similar study was completed in 2011 by the U.S. Geological Survey for Chaffee County (SIR 2014-5095 available on the district website and partially paid for by Custer County and Round Mountain Water and Sewer District). We should expect no less. Some of the money contributed annually by Custer County would be better spent on a Custer County aquifer study.

Custer County residents should continue to say no to the augmentation plan. Ask the district to exclude exempt wells from the plan. Attend district board meetings in Salida. (Meetings are typically the second Thursday of each month.) Voice your opposition to exploiting our groundwater aquifer to the Division 2 engineer andstaff,theCountycommissioners,ArkansasBasinRoundtablerepresentativesandUpper Arkansas Water Conservancy District board members. Seek to better educate yourselves about the complex hydrogeologic and water law environment as it pertains to our shared water resources in Custer County.

Groundwater & Wells in Colorado

 

Janet Smith

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