Torrential rainfall from Hurricane Alex and remains, followed by daily peltings of rain across the front range of the Sierra Madre Oriental, and concluding with the remnants of Tropical Depression Number 2 dropped perhaps 50 or more inches of rain across Coahuila Province, Mexico, which flowed steadily through the Rio Grande basin, requiring a series of planned flood control actions to mitigate the possibility of severe river flooding across the Lower and Middle Rio Grande Valley. Severe flooding in Monterrey, Nuevo Leon, M��xico from June 30th through July 2nd, from an estimated 30 inches of rain in this area was a portent of future impacts on the Rio Grande during the weeks to come, lasting for much of July and the first third of August.
Major flooding along the river south of Falcon International Reservoir continued through August 3rd due to maintained releases of 60,000 cfs at the dam. Flood conditions (50 feet or higher) continued a few days beyond, with levels dropping below flood stage on August 10th at 330 am CDT. In total, the river was in flood at Rio Grande City, and at points immediately upstream in Starr County, from the afternoon of July 8th through the early morning of August 10th, 33 days in total!
A number of small communities along the Rio Grande west of the Lower Rio Grande Valley Flood Control System were impacted by the now sprawling river for most of July, soon after the large releases began at Falcon International Reservoir. These included locations from Starr County immediately downstream of the dam, extending along the river to the Hidalgo County line. Voluntary and mandatory evacuations were ordered for a number of threatened communities; as of this writing, no fatalities had been reported directly from the high waters. There were dozens of water rescues on the river through the period, many of them transmigrants attempting to cross from Mexico into Texas.
On August 3rd, President Obama declared most counties in the Rio Grande Valley a Major Disaster, eligible for federal funding to assist with the longer term recovery. Deep South Texas Counties included Starr and Zapata (due to flooding). Property and Crop damages from the flood in Starr and Zapata Counties will ultimately total over $50 million when all assessments are completed. As of July 29th, property damage estimates in Starr County had reached $37 million; additional property damage values had not been received from Zapata County. Crops planted in flood zones were destroyed by the long duration of nutrient rich waters.
Note: The vast property damage estimates from the flood are provided in the July Storm Data report.

Flood in STARR, TEXAS
From 01-AUG-10 00:00:00 to 10-AUG-10 02:30:00 (CST-6)
Location: FALCON HGTS
Flood cause: Planned Dam Release
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Though the heavy rains had long since passed, and most days were dry from late July into much of August, release rates from dams and reservoirs across northeast Mexico tributaries flowing into the Rio Grande, as well as along the Rio Grande itself, continued at high levels into early August.
All of this water would continue impact hundreds of structures during the event.  The city of La Grulla remained under a voluntary evacuation into early August as waters began to recede slowly. As a precautionary measure in the city of Roma, three small subdivisions located in the low lying areas and along the bank just south of the Port of Entry were placed under mandatory evacuation. These included De La Cruz sub-division about (20 to 25 homes), Campo Verde (4 homes), and Garza sub-division (1 home). The flooding in Starr County had impacted at least 178 homes/businesses, including 65 in La Grulla and 39 in Roma.  166 families required temporary housing.  Preliminary damages to highways and bridges in Starr County was at $19 million; preliminary public and private property estimates were listed at an additional $18 million.  Agricultural damage was also notable in flooded areas.  Note: Since the bulk of the flood related damages occurred in July, dollar estimates are listed with the July report. [Data will be available later in September].