Arroyo Colorado, Rio Grande levees will hold

HARLINGEN - Even as the Arroyo Colorado overflowed its banks and the Rio Grande began to swell Thursday in the wake of Hurricane Dolly's deluge, officials said that the region's levees would hold and fears that they would fail were unfounded.

"We've had no problems whatsoever with the levees," said Sally Spener, spokeswoman for the U.S. section of the International Boundary and Water Commission, which is in charge of the region's flood control system. "We expect the river will continue to rise over the next several days, but we don't expect it will pose any problems for the U.S. levees."

The Rio Grande's water levels were rising throughout Thursday, according to IBWC's stream-flow gauges posted along the river. At the Progreso Bridge, water was rushing at 65 cubic meters per second Thursday afternoon, compared to 43 cubic meters per second the day before and the water level was inching up. The flow speeds up as the amount of water increases.

In Brownsville and near San Benito, the river's flow nearly doubled in 24 hours, according to IBWC data.

The Arroyo Colorado also rose rapidly during and after Dolly's strike - from about 7 feet in Harlingen Wednesday morning to nearly 25 feet by Thursday afternoon, according to the National Weather Service in Brownsville. The waterway also spiked rapidly near Mercedes.

None of these streams are considered to be in a flood stage, however, forecasters at the National Weather Service said.

Forecasters predict that waters will continue to rise until Sunday as rainfall upriver flows downstream. The Rio Grande should remain within its banks, though, meteorologist Alfredo Vega said.

Smaller arroyos and creeks could continue to rise, so residents should be on the lookout for minor floods, Vega said.

If needed, IBWC might divert some Rio Grande flows to floodways as the waters rise, but that's not yet certain, Spener said.

The heaviest rainfall in the storm occurred in northern Cameron County and southern Willacy County, which were soaked by about 14 to 16 inches of rain as of Thursday morning.

Other portions of Cameron and Willacy counties received about 6 to 8 inches, and Hidalgo County received an average of 6 to 10 inches, the National Weather Service reports.

The levees seem to be withstanding the increased flows, though, Spener said.

Several of the Rio Grande Valley's levees would be overtopped in a 100-year flood, IBWC officials have warned. The agency has struggled to obtain federal funding to repair the levees.

There is a 1 percent chance that a 100-year flood will occur in any given year.

Melissa McEver covers health and environment issues for Valley Freedom Newspapers. She is based in Harlingen and you can reach her at (956) 430-6252.