Project may help SLV retain water


ALAMOSA — When every drop of water counts, a local conservation district is proposing a creative way to keep more water in the area.

The Mosca-Hooper Conservation District proposes to use an imaging technique not used here before to determine how to better recharge the San Luis Valley’s aquifer system. They are planning to perform a pilot project on a portion of a township within the conservation district (Alamosa County) to see if this type of technology might help the Valley retain more of its water.

The district presented the proposal for the SLV Recharge Optimization Pilot Project to the Rio Grande Roundtable this week with a request for $43,100 in funding, or a little more than half the approximate $77,500 total for the project. The group will also receive some grant funding and in-kind donations. The roundtable board will act on the request during its October meeting.

Geologist Kate Ziegler of Ziegler Geologic Consulting LLC said she hopes the outcome of this project will be to become more efficient in getting water into the water table to help recover the aquifer. This is an important issue not only in the San Luis Valley but also in the entire western United States, she said.

“Lessons learned here can be transferred to other states and all over the western U.S.,” she said.

Ziegler said just as others will build on this project, she and other experts involved in this project are using existing information such as data compiled by Allen Davey, Davis Engineering, who is the district engineer for the Rio Grande Water Conservation District. She said she is not trying to undo or redo anything that’s already been done. She said Davey’s data provides a foundation and broad picture, while she hopes this project will zoom in to a microscale level.

The goal is to see if there is a better way to get water down to the water table to help recharge the aquifer through recharge ponds, ditches and other infrastructure, Ziegler explained. Hopefully the smaller scale of this project will show how a single pond or ditch might affect the water table, she added.

“How do we get water to where we want it go?”

The method for trying to answer that question is geophysical imaging, she added. This project will use Electrical Resistivity Imaging (ERI) technology to find out what is under the surface, for example if there is clay, fractures, sand, gravel or solid bedrock and where there is water in all of that.

The team will also use some shallow test holes to ground truth what it has been finding and compare the data, Ziegler explained.

Mosca-Hooper Conservation District Supervisor Patrick O’Neill said data exists for the top five feet and 40 feet and below, but there is a data gap between 5 and 40 feet, which is what he hopes this project will help fill in. (This project will take place in the unconfined or more shallow aquifer.)

“We believe this technology can inform us what is in the span of 5 feet and 40 feet because that’s what we have to try to get water into,” O’Neill said.

Ziegler said this type of technology has been used all over the world to determine locations of sinkholes, bedrock, old landslide areas, contaminant plumes, edges of landfills, caves, old pueblos and other features.

She said ERI has been used in California along with monitoring wells to see what a pond might do over time to the water table, and she said that would be the next step here — to see how a pond or ditch might make a difference in the water table. In California, it did affect the water table significantly, she added, when people had a better idea where to put a recharge pond.

“The idea is to start small, on the township scale,” she said. In fact the team will not map out an entire township but will place five or six arrays within a township.

Rio Grande Water Conservation District General Manager Cleave Simpson added that this pilot project on a small scale will help folks know if it provided valuable enough information to do something on a broader scale.

He said hopefully there would be some years when the runoff is good, and the Valley would need a place to put the water to recharge the aquifer.

O’Neill agreed when there is a greater volume of water, more rain and snow and runoff, it would be a shame not to be able to keep that water in the Valley and let it soak into the water table, and this type of technology could help the Valley do that.

“We would like to know when we have wet water where can we best place it,” he said.

The conservation district would like to start the project next spring.