Flood, Zapata
- When
- July 14, 4:00 AM CST to July 24, 8:00 AM CST
- Where
- Zapata County, 1.16 mi WSW of Zapata Arpt to 3.16 mi SE of Falcon Res South
- Cause
- Planned Dam Release
- Property damage
- $1.0 million
- Crop damage
- $25,000
- Reported by
- Emergency Manager
- Coordinates
- 26.876, -99.298
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 ultimately led to increasing water levels at both Amistad International Reservoir (northwest of Del Rio, TX) and Falcon International Reservoir (adjacent to Zapata County), the result of inflow from Mexican tributaries and upstream reservoirs along the Rio Salado and Rio Conchos in Nuevo Leon and Coahuila State, Mexico.
At Falcon International Reservoir, where inflow from both the upstream Mexican tributaries and Amistad International Reservoir, which had begun releases of 35,000 cubic feet per second (cfs) on July 5th, the pool level rose above conservation stage (301.2 feet) during the morning of July 12th, and would continue a steady rise, reaching moderate flood stage (306.7 feet, the point where impacts begin along the shoreline) during the pre-dawn hours of July 14th. Despite an increase in releases from 39,700 cfs to 60,000 cfs from the Reservoir, the pool level continued to rise, peaking at a new record stage of 309.31 feet during the evening of July 17th. The continued high pool level required maintaining releases of 60,000 cubic feet per second for nearly 14 consecutive days, in order to maintain a manageable water level at the dam. At Falcon, the previous record of 308.1 feet (set in October, 1958) was not only broken, but the pool level remained above the prior record for nearly 7 full days, from around 130 AM CDT on July 15th through 930 PM on July 22nd. The pool level was above conservation level (301.2 feet) from the morning of July 12th through 4 PM on August 13th, more than a month.
Releases were gradually lowered toward the end of the month as the pool level began to fall more steadily heading into early August.
During the period of time when the reservoir was in moderate flood, or above 306.7 feet, structures and infrastructure was impacted along the shoreline. At least 33 homes had some level of water incursion; damages were still being assessed as of this writing. Lakefront roads were under some water for weeks as well. Individual damage reports included an estimated $35.5 thousand to water pumps and related equipment. Business losses also mounted at the Reservoir, where bass fishing is popular. At least $15.3 thousand in losses was reported at Falcon State Park.
As of late September, a best estimate for property and infrastructure damage in Zapata County was at least $1 million; more is likely when the assessments are completed in autumn 2010.