The Rio Grande River is the lifeblood of South Texas agriculture.
The Rio Grande River is the lifeblood of South Texas agriculture.

Drought, whether political or natural, could cost the Texas Lower Rio Grande Valley nearly $400 million annually and 5,000 jobs.

Luis Ribera, an agricultural economist at the Texas A&M AgriLife Research and Extension Center in Weslaco, made that prediction, based on his analysis, according to a news release.

About half of the crops in the Rio Grande Valley rely on the Rio Grande River for irrigation.

Texas shares two reservoirs—Falcon and Amistad—with Mexico.

During recent droughts, Mexican has diverted more than its share from the reservoirs and has yet to repay the water.

"We believe the International Boundary and Water Commission has tools to compel Mexico to fulfill its obligations before the water debt becomes unmanageable,” Texas Agriculture Commissioner Todd Staples said in the release.

To determine irrigation water's value, Ribera calculated all crop production as if it were planted dryland.

Of the $820 million of crops grown in 2012, 81 percent—or $666 million—came from feed grains, cotton, sugarcane, vegetables, citrus and other crops. The remainder was from livestock and other ag-related production.

Without irrigation and the accompanying lower yields, the value of cotton, corn and sorghum would be reduced by $31 million.

Specialty crops, including citrus and vegetables, cannot be grown dryland and would be a total loss of $221 million.

Altogether, a lack of irrigation in 2013 would cost the valley about $395 million.

Indirect losses, including loss of jobs and infrastructure, were not factored in.