Crews continue working on flood control

HARLINGEN — Work crews will continue flood-mitigation efforts by removing vegetation along the Arroyo Colorado from Business 77 to FM 509, city officials say.

The second phase of the brush removal will clear 16 acres along approximately four miles of the river’s banks. The first phase, completed in February 2015, cleared 29 acres.

International Boundary and Water Commission crews are responding to a request from Harlingen officials to reduce water flow from other sources into the arroyo to diminish flooding.

By removing excess vegetation, city officials believe storm water runoff will move more efficiently into the arroyo without the backups that cause localized flooding.

“We are very pleased that the IBWC will improve our storm water drain capacity through the Arroyo Colorado by removing several acres of obstructive vegetation,” City Manager Dan Serna said in a statement.

During Rio Grande flood conditions, some of the floodwaters are diverted into interior floodway channels in Mexico and the United States, including the Arroyo Colorado.

A hydraulic analysis by the IBWC has shown that growth of dense vegetation and accumulation of sediment along the Arroyo Colorado have caused water surface elevations to be higher than in the past. Data have indicated that under current channel conditions, the Arroyo Colorado could only convey 45 percent of the floodwaters it was designed to handle.

Crews are clearing overgrown vegetation and removing obtrusive trees on both sides of the channel, but leaving a corridor for the protection and movement of ocelots and other wildlife.

The work along the arroyo will begin after bird nesting season is finished, officials said.