Mexican farmers protesting a 1944 water treaty with the United States have taken control of two dams, President Andres Manuel Lopez Obrador said on Wednesday.

The demonstrators on Tuesday closed the floodgates of the dams, located in Chihuahua state, which borders the U.S.

National Guard soldiers fired tear gas to disperse farmers armed with sticks who had gathered at La Boquilla dam in the municipality of San Francisco de Conchos, local media reported.

The soldiers finally left "to avoid confrontation," Lopez Obrador said.

He did not say which other dam was targeted by the protests.

The 1944 Water Treaty regulating the use of waters from the Colorado and Rio Grande rivers stipulates that Mexico hand the U.S. quotas of water.

The farmers argue that doing that this year would leave them without sufficient water for the agricultural season, following scanty rainfall.