[Editor's Note: This is part 2 of a multi-series of articles on the Oct. 3, 2017 New Mexico Central Arizona Project Entity regular meeting.]

By Mary Alice Murphy

After making a decision on the choice of an engineering firm, Occam Engineers Inc., to provide engineering expertise to members of the New Mexico Central Arizona Project Entity as they come closer to making a decision on a New Mexico Unit, board members discussed the previous week's AECOM report on the Potential components and alternatives of the New Mexico Unit.

The report preceded the release of the comprehensive 500+ page draft document, which was released on Oct. 6, 2017, and may be downloaded and viewed from this URL: http://nmcapentity.org/documents/reference-documents/57-version-2-nmcap-phase-ii-concept-development-and-selections-draft-final-100617 

NM CAP Entity Executive Director Anthony Gutierrez said the preceding week's report from AECOM "raised some questions. We can't forget that what AECOM is doing, they are doing with lots of on ground and hands-on experience. We can't forget that the engineering is based on what we have asked for in a New Mexico Unit. We want to make it more efficient for using the AWSA (Arizona Water Settlements Act) water, as well as the adjudicated water. The scope of work for AECOM is development of the AWSA water."

The board had determined the need for 3,000 acre-feet of additional firm yield water from the Gila River in the Upper Gila Valley and 1,000 acre-feet on the San Francisco River. "We have to take note that the design is related to those numbers," Gutierrez said. "This is not just a remedy for existing issues with the adjudicated system. It's a combination of on-farm storage ponds for direct delivery and for ASR (aquifer storage recharge). I know a lot of folks are not excited by ASR. We don't want all our eggs in the ASR basket. We've had questions about Ranney wells. We have to know the limits on them."

He said he appreciated Joe Runyan, who represents the Gila Farm Irrigation Association on the NM CAP Entity, "being active in thinking outside the box. We have to consider what is outside of our current scope. (Vance) Lee (representing Hidalgo County) talked with his constituents about on-farm storage in the Virden area. This is not in our scope."

Lee said in the previous week's special meeting, he had mentioned on-farm storage in Virden. "The answer was that it would be the same as on the Upper Gila. What would it take to make sure we are included in NEPA?"

"Currently you already have the means for diversion and delivery," Gutierrez said. "All parameters are in place. I don't see an issue including you in the proposed action. I presume we would need some additional data collection."

Lee said areas they have identified are not on-farm, but right next to farms. One area is on the north side of the river and was previously presented as potential storage. However, it had been determined not large enough. On the south side near the Lovett area, a parcel of land of about 20 acres has the potential to be much deeper than the north side one.

Hutchinson asked if Occam Engineers Inc., couldn't be doing that.

"I think there are restrictions," Gutierrez said. "Although Occam can do consultation, doing 30 percent design work is not in the RFP."

NM CAP Attorney Pete Domenici Jr. said Lee could talk to Occam to establish a range of depth. "That seems to be consultation."

"We have only a conceptual design," Gutierrez said. "I'm not too happy with the placement for the 35-acre storage ponds. I think other places are better."

Allen Campbell, representing the Gila Hot Springs Irrigation Association, said: "It's only a 30 percent design. Even on the Upper Gila, they have not set the actual locations. It's just an idea. We need the locations for NEPA, which are unknowns. We have unknown unknowns that we will run into. We have to locate the ponds later."

He said he had a question for all users to address. "From the beginning, we have to return the water to the river as far up as possible so is goes downstream. Isn't it allowable for the water to enter the river and go down to Virden?"

Gutierrez said the AWSA water can be stored up river, "but there are different restraints in the Virden Valley. We have to consider the losses, too. We have to measure the diversion and return and the second diversion."

Lee asked what would happen if not enough water is stored in the Upper Gila Valley.

Campbell said, if the CUFA (Consumptive Use and Forbearance Agreement of the AWSA) allows the storage, it becomes an engineering problem.

"We continue to talk about 30 percent," Gutierrez said, "but we're more at 10 percent. In speaking with Reclamation, they told me it is not uncommon for NEPA to start without all the analysis being done. We can do analyses in parallel with NEPA. We may find in NEPA that we may have to change things. For Virden, since they had a project earlier, they may have some analyses already."

Campbell said, if the water is released upstream in a wetter time Virden can pull it out to store during drier times. "Use the river as transport."

Gutierrez said CUFA will set the parameters.

Domenici said in the engineering contract with Occam Engineers Inc., No. 3 in the work order is the most important—consultation with the NM CAP executive director, with the board and with AECOM pertaining to the New Mexico Unit proposed actions. "The more precise the diversion, it keeps NEPA focused and cost-effective. We need the proposed action focused, but as broad as possible so as not to lose anything. We may have to eliminate some things. I think that's where we need Occam."

Kim Abeyta-Martinez, representing the Interstate Stream Commission as the no-voting member on the CAP Entity, said the task with AECOM is also to assist in preparing a letter to the Secretary of the Interior on the proposed action for a New Mexico Unit. "We don't want to duplicate AECOM and Occam tasks."

Domenici said a lot of discussion has talked about the on-farm storage ponds. "We can have lined ponds so we can store the water and pull it out for irrigation and to put into the river. It is different for those designed for infiltration, which will use wells to pull out the water from ASR. Can the ponds be used for both purposes to divert out of and also infiltrate from?"

AECOM's Paco Larsen, attending on the telephone, said the ponds could be used for irrigation. "We have studied them for infiltration. Those are not lined. Landowners can use the water, but I'm not sure how it affects their water rights."

"Is there a way to hold water and infiltrate more slowly?" Domenici asked.

"You may not be aware that fine particles will tend to fill the holes that infiltrate," Larsen said. "You will have to do maintenance to remove the silt."

Campbell said he had had experience trying to drain an infiltration pond, which under heavy flooding can "mud up. Taking a machine in when it's not dry, just makes it worse. You have to re-excavate. You are looking at a large cost to remove and haul a lot of material. If the pond is small enough, you can use a drag line. The problem with trying to use a pond as infiltration is that it will necessitate not taking water out in a flood."

Domenici asked if the board would get information on the different size ponds and different costs of Ranney wells and associated costs of those of less capacity.

Larsen said the sizing of the wells would meet design criteria for later phases of work.

NM CAP Entity Chairwoman Darr Shannon said she had received feedback that Ranney wells can plug up.

AECOM's John Sikora, also attending by phone, said Ranney wells are more efficient at transporting larger amounts of water if they are cased and drilled horizontally. Cost will be based on design and size. "If they are small enough it will keep out things that would block the well."

The next article will cover a discussion on a presentation by Jeff Riley of the Phoenix Office of the U.S. Bureau of Reclamation on gravity flow project components, gravity flow storage options, on-farm storage and other water information.