Rain fills Rio Grande, tributaries
Socorro County received “better than 50 to 60 percent of an average year’s precipitation in five days,” according to National Weather Service meteorologist Kerry Jones.
Three to 5 inches fell over most of the county last week, he said, with rainfall amounts between San Antonio and Bingham in the eastern part of the county estimated between 7 to 8 inches. Individuals have reported rainfall of 6 inches last week in the San Antonio area.
Statewide, record rainfall amounts saturated the watersheds above and around Socorro County, causing normally dry arroyos to dump runoff into the already full Rio Grande.
The Rio Puerco south of Bernardo rose to levels not seen since the 1960s, according to Jones.
A little after midnight Sept. 16, the U.S. Geological Service flow gauge at the old bridge spanning the Puerco west of the Interstate 25 exit at Bernardo measured almost 9,000 cubic feet per second of water rushing past. Soon after, the gauge was washed away.
A cubic foot holds about one gallon of water.
“The Rio Puerco came in excess of 10,000 cfs,” said Middle Rio Grande Conservancy District hydrologist David Gensler. “Nobody is really sure. It certainly was more than 8,000 cfs. The USGS is estimating based on the high water marks.”
The Kiva RV Park and Horse Motel near the exit was spared any flood damage, according to owner Bob Wiltshire, but residents of the tiny community of San Francisco south of U.S. Highway 60 and east of I-25 were not so lucky.
Socorro County emergency management coordinator Jerry Wheeler, the state police, and other entities were alerted early Sunday evening that problems might arise because of the high water.
“We had about nine to 12 families living in the San Francisco,” Wheeler said. “One of the families brought the wife and children out. The rest wanted to stay in there.”
Emergency management personnel continued to monitor the situation. At about 3 a.m., floodwater started to cross U.S. 60 at the railroad tracks. By 6 a.m., the highway had to be closed.
“By 6 a.m. it was up to 18 inches deep and 50 to 75 yards across,” he said.
A lot of the floodwater was flowing north and crossing over east of the railroad tracks, and Ramon Lopez Road leading south from U.S. 60 near the tracks to San Francisco was also getting inundated, threatening to strand the small community.
San Francisco resident Gary Hendrik and his wife, Debra, stayed in place, trying to keep water from flooding their home. At 1:30 p.m. Monday afternoon, Wheeler and a county worker operating a road grader helped Hendrik evacuate his wife.
“The road grader was on the canal bank, and graded part of Ramon Lopez,” Hendrik said. “He built up about a 2-foot berm from our community to the canal road, and then the drainage ditch broke.”
The county worker evacuated the county truck, but returned with the grader to help Hendrik and his wife and dogs escape to U.S. 60 while the canal road was still barely passable.
“We drove down the Unit 7 drain (road) with the grader,” he said.
Then Hendrik borrowed a four-wheeler to return to his home, where he stayed until rising floodwaters forced him to leave at 5:30 p.m. Four feet of water had already filled neighbors Chris and Richard Lopez’s house. The New Mexico National Guard brought him out in a six-wheel drive vehicle.
The USGS flow gauge in the Rio Grande at San Acacia showed 9,000 cfs flowing over the dam, over 400 times the normal September rate of 20 to 23 cfs, according to MRGCD hydrologist David Gensler. This week’s event was the largest sustained river flow Gensler has seen in his 18 years with the district.
“USGS was out there measuring,” he said. “It’s the biggest sustained flows we’ve seen at San Acacia in a long time. They haven’t measured sustained flows over 8,000 cfs for more than 24 hours. Usually it lasts for 15 minutes and it’s gone.”
The pulse of water caused the river to overtop its normal channel east of Socorro south through San Antonio and the Bosque del Apache, according to MRGCD hydrologist David Gensler, who drove south from the dam checking on flow conditions. The river stayed within its channel until the riverine parks east of Socorro.
“The over banking starts in Socorro within a mile south of Otero Street,” he said. “It was starting to get in the bosque at Brown Arroyo.”
At midnight on Monday morning, U.S. Highway 380 east of San Antonio flooded when a berm broke that protected the road from a flooding arroyo draining into the Rio Grande. The highway was closed until 6 a.m. Monday.
The river levels peaked in San Antonio Monday night.
The water level rose 6 1/2 feet at U.S. 380 in San Antonio after the rains subsided, Gensler said.
“It’s over banked on both sides, so it’s up against the levee,” he said. “At San Antonio 380, it probably came out of the banks somewhere around 32 feet. A 4-foot value brought it over the banks. It’s probably 6 or 6 (feet) below the top of the levee. The levee is doing its job.”
Gensler emphasized that over banking into the bosque flanking the river channel maintains the native vegetation and is welcome.
“It’s good, we like to see the over banking,” he said.
The levee is designed to contain the flow within a limited floodplain.
“It’s to keep the river from coming into the populated areas and causing problems,” he said.
Mike Jojola, Socorro County facilities and maintenance supervisor and San Antonio resident, said some low-lying areas in the town of San Antonio had ponded water, but no flooding from the river.
Aaron Mize, deputy refuge manager at the Bosque del Apache National Wildlife Refuge, reported no breaks in any of the Rio Grande levees on the refuge. The Rio Grande overtopped its banks, but was contained in the flood management area.
“It flooded in the active flood plain, but the levee protected it from coming into the historic flood plain,” he said.
“We had concern that the Rio Grande could rise high enough to potentially threaten the levee. While it reached the levee, it didn’t get near the top, and the levee held.”
The tour loops had been closed for three days during the height of the storm.
While there was no flooding, roads did get muddy. The refuge reopened the bird watching areas for visitation this week.
“A lot of roads have dried, and we’ve regraded them,” he said. “We’re open for business. We had closed the tour loop for three days as a precaution.”
Socorro County official rainfall amounts, most to least, Sept. 10 through 15, 2013
Information provided by National Weather Service in Albuquerque:
10 miles southeast of Socorro – 5.30 inches
Bosque del Apache NWR – 4.62 inches
VLA near Datil – 4.41 inches
Socorro airport – 4.17 inches
10 miles SE Magdalena – 4.12 inches
25 miles SW of Bosque del Apache NWR – 3.78 inches
14 miles east of the Bosque del Apache NWR – 3.72 inches
Contreras – 3.49 inches
Gran Quivera – 3.41 inches
Chupadera (15 miles NW of Carrizozo) – 3.41 inches
San Antonio – 3.23 inches
La Joya – 2.79 inches
Bernardo – 2.23 inches
San Acacia – 1.35 inches