US Army Corps of Engineers
Albuquerque District

Flood Fighting: District Assists Effort to Lower Bonito Lake

Albuquerque District Technical Writer / Editor
Published Aug. 1, 2012
Pumps pull water to help lower Bonito Lake.

Pumps pull water to help lower Bonito Lake.

The June 2012 Little Bear Fire burned 44,330 acres of private and Lincoln National Forest land in southern New Mexico, the majority in a wedge of prime timberland surrounding Bonito Creek. Beautiful, clear Bonito Lake, water supply for the City of Alamogordo and for Holloman Air Force Base, was overrun by the flames, which also burned 242 homes and 12 additional structures on the checkerboard lands adjacent to the lake. Looking up the steep hills from Bonito Lake, high and moderate severity burned land extends to the top of the ridge and most of the pinion, juniper, Ponderosa pine and other conifers are dead and blackened; the litter of pine needles has turned to ash. Loose sediment, charred woody debris and dead trees cling precariously to the slopes.

What made the area around Bonito Lake a beautiful refuge for people and animals is now the region’s enemy; with ridge tops exceeding 11,900 feet in elevation, the mountains surrounding Bonito Lake promote the development of thunderstorms during the summer monsoon season. The abundant summer rain trickling through the dense canopy and sinking into the deep litter of the forest floor had nourished the forest and provided the clear water to Bonito Creek that had collected behind the dam at Bonito Lake.

But in the now-devastated watershed, such storms are the enemy. Heavy rainfall on the denuded, unstable slopes does not sink into the ground, but runs off with frightening speed. Dirt and woody debris are stripped from the hillsides and carried down slope in a churning mass of debris that flows faster than a man can run. Such immensely turbulent flows destroy whatever is in the way, including roads, unburned forest and structures of all sorts. Everyday storms become deadly in post-fire moonscapes such as the Little Bear Fire burn area.

The onset of the 2012 monsoon season in late June put everyone on edge. The first major storm struck the basin on June 22, washing soil from portions of the drainage at a rate of about 30 tons per acre according to the Little Bear Fire Burned Area Emergency Response (BAER) Team White Paper (July 3, 2012). A storm on July 5 washed a great quantity of silt, debris and ash into the lake from the surrounding water-shed, plugging the outlet pipes. The lake rapidly rose to seven feet below the spillway as water continued to flow in but not out.

During the next several days, two pumps borrowed from Doña Ana County and one from the Bureau of Reclamation were installed to drain water from the lake, but the pumps could not keep up with the rising water.

Desperate, the downstream Village of Ruidoso called upon the Albuquerque District for assistance and found that the District’s Readiness and Contingency Operations (RCO) Branch had anticipated their need. As a matter of fact, funding had already been requested and received from Division before the official state request came in. Under the PL 84-99 Advance Measures – Direct Assistance (Class 510) program, the Corps is able to assist communities threatened with imminent flooding potential in order to protect life, public facilities and infrastructure.

On Saturday, July 7, 15 District employees worked a long day identifying a vendor and awarding a contract for two additional pumps. The employees represented Resource Management, Emergency Management, Contracting, Program Management and Planning and Project Management.

Don Gallegos, the Albuquerque District’s Natural Disaster Preparedness Program Manager, had already been down to the Little Bear Fire area twice to help coordinate flood control efforts as this year’s monsoon set in. After the rain event of July 5, he was dispatched to oversee the installation of the pumps and to provide additional assistance along with Hydraulic Engineer Steve Boberg, Civil Engineer John Stages, Regulatory Specialist Eddie Paulsgrove and Chief of Geotechnical Engineering Shelley Ramos.

The two new pumps from Rain for Rent arrived on July 9, and the race was on to install them. The pumps had to be placed on level ground at the same elevation as the dam spillway, and land that fit the criteria was hard to come by on the steep slopes surrounding the lake. Ultimately, the pumps were situated on the north shore and nearly 1,600 feet of piping had to be laid in the pouring rain for the two new pumps (and the three existing pumps) to take the water from the pump intake down to and across the dam crest to the spillway. As if to underscore the urgency of the situation, the lake rose another 18 inches during the night, despite the three pumps already active on site.

By the next evening, the first new pump was operational and, by the following day, the second was active, a day ahead of the contract schedule. Even with continued fouling of the pumps due to the large amount of debris in the water, water levels in the lake began to slowly drop. Quiet weather over the weekend of July 14 and 15 allowed water levels to fall to a little less than 10 feet below the spillway. By July 19, lake levels stood at 14.1 feet below the spillway, having dropped just under a foot per day with the addition of the Corps’ pumps.

That same day, the contract for operation of the pumps was passed to the City of Alamogordo. “The District’s swift action fulfilled a critical safety need until the City could enact longer term solutions,” said Acting Chief of RCO Cheryl Buckel.

All is not roses, however, and no one is walking away just yet. It is still early in the monsoon season and, despite all the excitement so far, there has not really been a significant precipitation event over the burn scar.

“The goal of the pumping is to create as much space in Bonito Lake as we can to contain the next event. But if that event is large, the potential exists for a flood to go through the emergency spillway,” said Gallegos.

Gallegos also points out that only a portion of the burn scar has drainages that enter into Bonito Lake or Bonito Creek above the lake. The remainder of the high and moderate severity burn slopes drain either into the Bonito Creek below the lake or into the adjacent Eagle Creek drainage above Alto, posing significant threats to downstream areas, including Alto Reservoir, which supplies water to the Village of Ruidoso.

Significant precipitation over any portion of the burn scar could have devastating consequences for downstream communities, nearby municipalities and Holloman Air Force Base.

Ultimately, the amount of assistance that can be rendered to fire-stricken communities by the Corps is limited by the nature of the authorities that govern assistance. Laws enabling Mississippi Basin communities to prepare for spring floods a month or more in advance don’t always apply where the “inevitable big one” is less predictable in time, but comes with only an hour’s warning. Yet, as large fires increase in size and frequency, this is the kind of flood emergency that is increasingly common for communities in and downstream of burned areas of the West.

“We’re all committed to helping affected communities, but the way the authorities are written, we are limited in how we can help,” said Hydraulic Engineer Stephen Scissons.