A nearly seven-decade-old agreement between the U.S. and Mexico over water sharing has people in the Texas borderlands upset, claiming that Mexico has not been giving its share of water.

The agreement signed in 1945 obligates Mexico to share 350,000 acre feet of water per year from the Rio Grande with the U.S., in exchange for water from the Colorado River in the U.S., according to The Washington Post.

Mexico is 380,000 acre feet of water behind, an amount that is more water than the 1.5 million people in the Lower Rio Grande Valley in the U.S. use in one year. Mexico says it's not trying to withhold water from the U.S., there's just not enough water.

"The U.S. gets angry: Why aren't you giving us water? Well, how can we when there is no water?" said Mexican Engineer Roberto Enriquez de la Garza. "I can't do anything. It's not raining."

The treaty stipulates that in the event of extreme extenuating circumstances - like a dam failure or extraordinary drought - the water quota can be made up over the next five-year period. Mexico claims that it's been facing extraordinary drought.

"We have had a prolonged drought since 1994 until now. It has been difficult for Mexico to give this water," said Ignacio Pena Trevino, Mexico's representative on the International Boundary and Water Commission. "There isn't rain like there was in the past."

But water officials in Texas say that in recent years the Mexican drought hasn't been as bad as it was.

"They haven't been in any sort of significant drought conditions since March of 2012," said Carlos Rubinstein, chairman of the Texas Water Development Board. "That excuse, pardon the pun, doesn't hold water."

Texas has also seen an improvement in drought conditions since 2011, when all the state's 254 counties declared a drought. But certain parts of the state are still facing sever drought.

Texas A&M University released a study that Mexico's inability to share water from the Rio Grande has cost $229 million and 5,000 jobs, all relating to agriculture.