Updated

Twelve-foot-high earthen berms stretching 100 miles along the Rio Grande in South Texas were built decades ago to protect the region's irrigated farms and citrus groves from floods. But now a four-county region known as the Valley, with a growing population of 1.3 million, risks flooding again because of levee erosion.

Age, drought and poor maintenance are part of the problem, but locals blame the U.S. Border Patrol for the worst damage. Agents drive along the tops of levees, often dragging tires behind to wipe out footprints of illegal immigrants so fresh ones will be more noticeable.

"The levees were not designed to have that sort of traffic flow on them," Cameron County Judge Gilberto Hinojosa said. The agents are "just doing their job, but it has had an effect on a system that was designed to protect us."

Irrigation drains once encased in dirt now have several feet of cement base exposed.

Mario Villarreal, assistant chief for U.S. Customs and Border Protection's Rio Grande Valley sector, said he was unaware of concerns about agents driving on the levees because farmers and other law officers do it, too.

"Our agents are on the levee; they're on the lower river road. We have a responsibility to protect the nation's border and it is critical that our agents move laterally," he said.

Hinojosa told a state Senate Committee on Transportation and Homeland Security in July that the federal government should take responsibility for levee repairs.

U.S. Rep. Ruben Hinojosa (news, bio, voting record), who is unrelated to the judge, got $6 million added to a House appropriations bill in June to repair the levee, which is about three times more than the annual $2 million allocation for maintenance. The bill is still pending in Congress.

Carlos Marin, acting commissioner of the federal International Boundary and Water Commission, which oversees the U.S. side of the Rio Grande and its levees, said $6 million is not enough to protect against a flooding disaster. He estimated $125 million was needed for repairs, but said south Texas is a low priority after Hurricane Katrina.

"Everybody basically in the country is now concerned about levee systems, so we're competing with other places, like New Orleans," he said.

Afraid that Washington won't act quickly enough, local officials put a $100 million bond referendum on the November ballot for flood drainage projects.

Pete Leal, 61, fears the levee won't withstand another major storm if repairs aren't made soon. In 1967, Hurricane Beulah dumped three feet of rain on the Valley. Flood water surged about 200 yards past the riverbank and lapped the top of the then-sturdy berm.

"If anything like that happened now, I'd say it would wipe out Brownsville," Leal said.