The purpose of the agreement is to pave the way for future road projects between the county and the tribe, San Juan County Public Works Administrator Dave Keck said.
The two governments first entered an agreement with each other in 2007. They must vote to continue the relationship every five years.
"We call it an agreement to agree," Keck said. "It sets the framework for future agreements."
In the last five years, the only collaborative project between the county and the tribe was road-improvement in the southern portion of the county, Keck said. The tribe gave the county $800,000 to complete improvements on a tribal road.
By approving the agreement Tuesday, neither the county nor the tribe committed any funds. The commission and the tribe will have to approve any future work project that stems from the agreement.
Keck said that in the future the county and tribe may work together to replace a bridge near Huerfano. Paulson Chaco, the director of the Navajo Division of Transportation, said the tribe has already allocated $1.5 million to replace the Military Bridge on County Road 7150 near Huerfano.
He said the tribe will pay for the bridge replacement work.
The bridge is on a county-maintained road but it is primarily used by Navajo communities in the area, Keck said.
The agreement would allow for the tribe to contract county crews that would respond to reported problems or for the county to sell supplies to the Nation.
Commissioners unanimously approved the agreement.
"I hope this (agreement) will lead to great collaboration to get roads fixed," said GloJean Todacheene, a county commissioner who represents the Shiprock area. "Anytime we can work together for the good of the citizens it's a good thing."
Also on Tuesday, commissioners approved an increase in the per-day rate charged to municipalities when a resident spends a night incarcerated at the San Juan County Detention Center. Cities only have to pay for their residents' stays when the person is sentenced to jail by a municipal judge.
The rate increased from $67.79 per day to $70.13 per day.