FARMINGTON — A proposal to conduct an annexation petition for unincorporated land southwest of Farmington received unanimous support from city council Tuesday evening.

The proposed area is about 1,138 acres along the southwest side of Farmington, roughly sandwiched between West Pi–on Street, the San Juan River, South Allen Avenue and the Upper Fruitland Highway.

The city already owns about 205 acres of land in the area, including a wastewater treatment plant and the current animal shelter, according to documents included with Tuesday's meeting agenda. About 25 acres in the area are owned by San Juan Regional Medical Center. About 27 businesses and 110 residences were located in the area in 2010.

If approved, the annexation would increase the city's land by 5.2 percent.

"Our cost-benefit analysis is favorable," said Mayor Tommy Roberts in a phone interview before Tuesday's meeting. "It appears that the revenue associated with annexation in the short-term and in the long-term would exceed the cost of providing services. This area is contiguous to existing city limits. The city-county line in that part of town doesn't make a lot of sense."

According to a Community Development Department cost-benefit analysis, annexing the area will cost $189,915 in annual expenses in the short-term and $110,500 in one-time capital costs. But it is expected to generate $10,178 in property taxes annually and $505,000 in gross receipts tax collections.

Over the long-term, the department study estimates that there will be $480,587 in annual costs, $650,000 in one-time costs, $32,152 in annual property tax collections and $1,204,006 in gross receipts tax collections.

In order to use the petition annexation method, the owners of the majority of land in the proposed area must give their signatures of support.

The city, however, was unable to get the required percentage of support to annex using the petition method, Roberts said.

Many property owners of large pieces of land in the proposed area have signed the petition, according to a Community Development Department report. However, the city is still short about 30 acres.

City council previously asked the department to meet with property owners to encourage them to sign the petition. But the city has still been unable to get the majority acreage, according to the documents.

"I'm supportive of it," said Councilman Dan Darnell in a phone interview before Tuesday's meeting. "We've been dealing with this for several years. We were looking at how much land the city had. We had land off of the Bisti (Highway). The power plant is out there."

Darnell, however, has his doubts about two other annexation methods proposed by the Community Development Department: arbitration and boundary commission.

"I'm not sure I can support (them)," he said.

Darnell said he spoke informally to some property owners.

"Some have told me that they haven't signed the petition, but that they're on the fence," Darnell said Tuesday evening. "It's their property. I want everyone to come away from this with a good taste in their mouth."

Greg Yee can be reached at; 505-564-4606. Follow him on Twitter @GYeeDT.