HARLINGEN — Spurred by memories of last June’s record rains, and the looming hurricane season, city officials from across the Valley met yesterday with the top official of the International Boundary and Water Commission to discuss rising concerns about flood control.
IBWC Commissioner Jayne Harkins and principal engineer Daniel Avila were in Harlingen to discuss a regional response to recent agency proposals for dredging the Arroyo Colorado and slashing vegetation choking its banks.
“The June flood that we experienced was such that we had several cities — Weslaco, Mercedes, us here in Harlingen — that had water damage in homes, we had several roads that were flooded causing damage to the roads, and it was extensive,” Harlingen City Manager Dan Serna told IBWC officials.
Serna said the damages totaled in the million of dollars, and pointed out that the arroyo was carrying 5,000 cubic feet per second and hit an elevation just below 24 feet at the flood gauge in Harlingen. IBWC engineers say the arroyo should be currently able to carry off 85 percent of its 21,000 cfs capacity.
“The improvements that were done in 2014, 2017, to remove some vegetation, was supposed to bring it back up to an acceptable level, about 85 percent (of capacity) I believe,” Serna added. “But what we experienced in 2018 with the flood was that at 5,000 (cfs) we were underwater in several areas at an elevation of 24. I believe the study from (IBWC engineer Apurba Borah) indicated that at 85 percent we can get to an elevation of what, almost 29 feet?
“At 29 feet, I don’t even want to imagine what that looks like,” he said.
The record rainfall of 16.85 inches in just 72 hours last summer in Harlingen has added urgency to efforts to find answers to what many say is a deteriorating flood-control system in the Valley.
The IBWC’s Harkin was appointed commissioner in November by President Trump. An engineer, she is former director of the Colorado River Commission of Nevada and is experienced on water and hydropower issues.
City officials doubt the Arroyo Colorado can reach 85 percent of its 21,000 cfs capacity IBWC engineers say it can. Years of siltation and vegetation growth have severely restricted flow rates along what is a crucial flood-control pathway for the Valley.
This month, the IBWC announced a plan to carve a 50-foot vegetation-free buffer along the arroyo banks beginning at 77 Sunshine Strip/U.S. 77 and extending downstream nine miles to the Port of Harlingen. Flood-plain vegetation would be trimmed back from 77 Sunshine Strip/U.S. 77 to the Union Pacific rail bridge No. 2 downstream.
The channel also would be dredged to a depth of three feet from 77 Sunshine Strip/U.S. 77 to Cemetery Road Bridge near the Port of Harlingen.
“What I didn’t like when we met two weeks ago at the IBWC office in Mercedes, when we asked about organizing the city and working alongside IBWC to improve what we’re just discussing today, we were told no, that’s something y’all have to do,” said Mercedes Mayor Henry Hinojosa. “I find that very disappointing. You would think that the feds would take the lead but they literally washed their hands. … That was very disturbing to us.”
IBWC Commissioner Harkins said she appreciated the mayor’s candid assessment of the meeting.
“I appreciate your comments, I wasn’t there,” she said. “I’m here trying to figure out what this is.”
City disputes plan
Harlingen officials disputed the claims IBWC engineers made at the meeting this month in Mercedes.
In a written rebuttal presented to Harkins and IBWC officials yesterday, city officials said clearing and removing choking vegetation along the arroyo will not provide the flow rate needed.
“The City of Harlingen questions the practicality of being able to implement the mitigation plan,” the document said. “Reduced rights of way, terrain with steep slopes and environmental protection regulations are a few factors that would restrict clearing the arroyo.”
The city document further stated that, while clearing vegetation and dredging the arroyo channel is well and good, the proposal by the IBWC doesn’t go far enough.
“The city supports a reduction of flows being routed through the arroyo by diverting waters to the North Main Drain and creating regional detention facilities at strategic locations throughout the arroyo,” the document concluded.
Who has responsibility?
What city officials in the Valley and the IBWC do agree on is the flood system needs further study.
“This is a system that was designed 70-plus years ago, and it was implemented 70-plus years ago when the region was primarily an agricultural economy, and that was it,” said Harlingen Mayor Chris Boswell. “And the economy has diversified tremendously, the region has grown tremendously, but we’re using a 70-year-old system that doesn’t work.
“No one should expect a 70-year-old system to be applicable after all the development,” he added. “We need to find and come up with a solution.”
Maintenance of the arroyo, such as dredging and trimming back vegetation, is the responsibility of the IBWC.
But as Harkins pointed out, the primary task of the agency is to oversee international water treaties with Mexico, and the agency’s priority is not necessarily flood control.
“Our agreement with Mexico and the state down here since Hurricane Beulah, which I think was a Category 5 … they were going to take so much water their way, we would take so much water in the United States in the North Floodway, and the Arroyo Colorado was supposed to take the United States’ portion of it,” she said. “We know that time has silted it in and you probably couldn’t get those volumes of water through.
“I think our authority would tell us I only need to pay or try to find or have the authority to get it to the design flows of what we agreed with Mexico,” she added. “I don’t know that there’s a priority of things but if you want … larger capacity for drainage flows, I don’t know that’s something our authority can do.”
Study, but where?
Municipal and IBWC officials agree the first step toward any solution to the Valley’s flooding issues begins with fresh data. But what to study and where, and who pays for them, remains undetermined.
“I don’t see how without data we can make the claim that 50 feet of vegetation is going to bring us back to 21,000 (cfs) when the (arroyo) was an open channel to begin with,” Serna said, referencing historical photos which show the Arroyo Colorado’s broad and deep channel that existed decades ago when that flow rate was determined.
“We’re willing to work with you guys, just tell us what it is you want us to do, so we can help ourselves,” he added.
Ron Garza, executive director of the Lower Rio Grande Development Council, offered his agency’s resources as a liaison with the IBWC to help pinpoint which studies are needed and where.
“We just created a formal advisory committee for regional water resources to just kind of do exactly what you want to do, gather information, so it could be a conduit for the cities,” Garza said.
Harlingen’s June flooding
75 — Number of roadways flooded
42 — Number of homes with damage
3 — Businesses flooded
$1.8 — Millions of dollars in damages
Source: City of Harlingen