Flooding in Texas, July 9 to 31, 2010

Incredible rainfall estimated to be more than 50 inches in around 10 days' time between June 30th and July 9th across the front range and peaks of the Sierra Madre Oriental in Coahuila Province, Mexico, ultimately flowed through the entire Lower Rio Grande basin for much of the summer of 2010.

The rare and extreme event rapidly produced major flooding along the river in southwest Hidalgo County, the result of planned dam releases from Falcon International Reservoir. River flooding likely began along the banks of the Rio Grande in Hidalgo County less than 18 hours after flooding began at river side locations in Starr County. Affected communities included Cuevitas, Havana, and the south portions of La Joya and Penitas - locations not protected by the Lower Rio Grande Valley Flood Control Project levee system. The city of Los Ebanos, surrounded on three sides by the river, was most impacted by the flood, which was well over a mile wide for several weeks. Significant flooding continued into the first days of August.

Mandatory evacuations were initiated on July 12th for Los Ebanos, in the southwest corner of the County; the evacuation level was reduced to voluntary on July 20th. The early evacuations proved fateful, as pressure on a retention pond dike caused it to rupture, spilling water into some neighborhoods and forcing most residents to leave the area. Additional impacts were noted between Los Ebanos and the Anzalduas Diversion Dam, where several residences and roadways were threatened prior to the levee south of Mission.

In all, hundreds of structures, as well as paved and unpaved roads, were damaged significantly by the long duration flood. Most of these were in Los Ebanos, but others were along or south of Military Highway between Cuevitas and the south portion of Penitas. Five homes were evacuated near Military Road in Havana where the river flooded them. Damage to property was estimated to be at least $5 million, with additional damage to crops in southwestern Hidalgo County.

Note: Total value of irrigated and non irrigated dryland crop (sorghum, corn, and cotton) was not available for locations west of Anzalduas; an early estimate of $1.5 million between Los Ebanos and Penitas will be updated as information arrives.

Incredible rainfall estimated to be more than 50 inches in around 10 days' time between June 30th and July 9th across the front range and peaks of the Sierra Madre Oriental in Coahuila Province, Mexico, ultimately flowed through the entire Lower Rio Grande basin for much of the summer of 2010.

The rare and extreme event rapidly produced major flooding along the river in southwest Hidalgo County, the result of planned dam releases from Falcon International Reservoir. River flooding likely continued spreading southeast into the area that begins the improved levee system of the Lower Rio Grande Valley Flood Control Project, south of Penitas and extending to Anzalduas Diversion Dam where the system of floodways (spillways) begins. While the levees protected most property behind them, a number of structures built inside the levees suffered significant and costly water damage, from Penitas to south of Granjeno.

The structures included the popular river front Chimney Park RV Resort, which had more than 3 feet of water cover half of the land and property; Pepe's on the River Bar and Grill and the Riverside Club, favorite haunts for Winter Texans and local residents alike which provide river views but unfortunately were covered by feet of mud after the flood waters subsided. A sugar grower reported $450 thousand in losses of 300 acres of crop on land south of Mission. Dryland/irrigated dryland crops such as cotton, corn, and sorghum may have suffered some loss but values were unknown as of this writing; an estimate of $500 thousand will be used until additional data arrive.

Property damage likely exceeded $5 million in these areas alone.

Incredible rainfall estimated to be more than 50 inches in around 10 days' time between June 30th and July 9th across the front range and peaks of the Sierra Madre Oriental in Coahuila Province, Mexico, ultimately flowed through the entire Lower Rio Grande basin for much of the summer of 2010.

Nearly a month of dam releases from Falcon International Reservoir at 60,000 cfs ultimately required water to be diverted at Anzalduas Dam (southwest of Granjeno) into Mexico and the U.S. Floodway system, which includes the Banker Floodway (from near Granjeno to just south of Pharr), the Main Floodway (from just south of Pharr to the split at the Arroyo Colorado just southwest of Mercedes, the Arroyo Colorado itself, and the North Floodway, which extends from near Mercedes to near La Villa before curving east to northwest Cameron County.

These floodways, protected by a robust system of levees and gates, protected communities outside of the levees by containing up to 50%, or 4 to 8 to feet of fast flowing water, within them. Unfortunately, a number of residences, dozens of paved and unpaved roads with low water bridges, and some agriculture are located within the floodways; significant damage was noted in several locations. Pumping and plugging operations near Weslaco and La Villa successfully kept high water out of poor drainage locations where the potential for freshwater flooding due to heavy rains would have been exacerbated with periodic thunderstorms, which only came once (July 26th). Closed roads included FM 493 and FM 1015, each moderately traveled; at least five homes were flooded along the Main Floodway south of Pharr along I Road; 15 to 20 homes were asked to voluntarily evacuate, and at least two other residences were flooded south of Weslaco near FM 88. Floodwaters also submerged portions of the Llano Grande golf course in Mercedes.

High flowing water along the river covered a large portion of the Lower Rio Grande Valley National Wildlife Refuge (Santa Ana) south and southeast of Pharr, including a number of unpaved roads. Damage to the roads was unknown at this time; the flooding occurred downstream of the Anzalduas Diversion Dam; river gages downstream at San Benito and Brownsville remained in action stage. Floodwaters did not reach public or private structures, nor roadways, between the Refuge and the Main Floodway.

Nearly $5.2 million in lost dryland/irrigated crop yield was lost in and near the Floodway system in Hidalgo County. One of the grain losses was $50 thousand, including 170 acres of unharvested land in the Main Floodway south of Donna. Several other crops such as cotton, corn, and citrus were destroyed by the flood along the Main and North Floodways. For cotton, a little over $1 million was destroyed; for corn, a little over $500 thousand was destroyed, and for sorghum, more than $3.5 million was lost. The cost for re-leveling damaged cropland in and near the Hidalgo County portion of the floodway was $7.5 million.

Other property and infrastructure damage likely exceeded $5 million in and near the Floodway.

Incredible rainfall estimated to be more than 50 inches in around 10 days' time between June 30th and July 9th across the front range and peaks of the Sierra Madre Oriental in Coahuila Province, Mexico, ultimately flowed through the entire Lower Rio Grande basin for much of the summer of 2010.

Nearly a month of dam releases from Falcon International Reservoir at 60,000 cfs ultimately required water to be diverted at Anzalduas Dam (southwest of Granjeno) into Mexico and the U.S. Floodway system, which includes the North Floodway which curves east across northwest Cameron County just south of Sebastian.

These floodways, protected by a robust system of levees and gates, protected communities outside of the levees by containing up to 50%, or 4 to 8 to feet, of fast flowing water, within them. In Cameron County, there were no reports of structural damage as the North Floodway tracks in largely uninhabited country. However, several paved and unpaved roads were flooded inside the levees, including the Federal Highway 77 (Expressway) frontage road (the Expressway was well above the water level), County Road 506, and FM 1425 (along the Cameron/Hidalgo County line)

Crops may have been destroyed by the flood along North Floodways, but damage in northwest Cameron County was unknown as of this writing. Infrastructure damage to roads and low water bridges may have exceeded [$x] thousand in northwestern Cameron County.

Incredible rainfall estimated to be more than 50 inches in around 10 days' time between June 30th and July 9th across the front range and peaks of the Sierra Madre Oriental in Coahuila Province, Mexico, ultimately flowed through the entire Lower Rio Grande basin for much of the summer of 2010.

Nearly a month of dam releases from Falcon International Reservoir at 60,000 cfs ultimately required water to be diverted at Anzalduas Dam (southwest of Granjeno) into Mexico and the U.S. Floodway system, which includes the North Floodway which curves east across southeastern Willacy County between Sebastian and Santa Monica.

These floodways, protected by a robust system of levees and gates, protected communities outside of the levees by containing up to 50%, or 4 to 8 to feet, of fast flowing water, within them. In Willacy County, there were no reports of structural damage. However, FM 507 and FM 1420, as well as several paved and unpaved county roads, were closed at low water crossings inside the levee. On July 17th, a leaky levee valve required pumping water away from homes just east of FM 1420 immediately north of the Levee Road near Santa Monica.

Crops may have been destroyed by the flood along North Floodway, but damage in the Willacy County portion was unknown as of this writing. Infrastructure damage to roads and low water bridges may have exceeded [$x] thousand in southeastern Willacy County.