Los Alamos dam construction complete

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By Arin McKenna

Thirteen years after the Los Alamos Reservoir was closed in the aftermath of the 2000 Cerro Grande, dam reconstruction is finally complete and the reservoir is slowly filling.


That does not mean the reservoir is “open for business” just yet. In fact, reviving the treasured picnic area and fishing spot many residents hold dear is at least two years down the road.

The road itself is one reason for that. A flood following the Las Conchas fire in 2011 obliterated 75 percent of the road. A temporary road constructed the spring of 2012 was wiped out in a flood last summer. The road was repaired sufficiently to allow construction crews access, but a major reconstruction is necessary to safeguard against future flooding.

That work will take place this summer, which means the reservoir, remains off limits until construction is complete.

The overall final cost of the project was $4,888,789.56. Since the Las Conchas fires and the subsequent floods were declared natural disasters, $1,430,617 of that amount is eligible for Federal Emergency Management Agency (FEMA) funds.

Crews have already begun hauling dirt from the Eastern Area construction to begin building up the road, which lies level with and, in places, lower than the streambed. The plan is to build the road two- to four-feet higher. Crews will then install gabion baskets alongside the roadbed to armor it against flooding and install culverts to redirect any overflow.

The reservoir itself is unlikely to be full before September. The lake has a 22-acre-foot capacity and is filling at approximately one acre-foot per week. It was exactly nine-feet deep on Monday.

“We’re trying to fill it up, but because of timing and permission from the State engineer’s office, it just didn’t work. We missed the spring runoff,” Department of Public Utilities Deputy Utilities Manager Tim Glasco said. “So we’re filling it at a very slow rate. We could have done it in a matter of weeks during the spring runoff. Now we’re talking probably six months.”

A significant monsoon could help speed the process, but Glasco does not anticipate much gain even from that.

There are no plans to restock fish until at least the end of the summer. There is a strong possibility more debris from the Las Conchas fire will wash into the reservoir during monsoon season, which could require dredging.

“Dredging is a really expensive proposition. We’re hoping by now that the watershed is recovered enough that we won’t get those torrential floods,” Glasco said. If sediment does wash down, the hope is that it deposits at the upper end of the reservoir so crews only have to partially drain it in order to dredge or that a “dead pool” below the outlet collects most of the finer sediment.

Although the Parks and Recreation Board has toured the reservoir, additional development such as a picnic area is just a “twinkle in the eye,” according to Public Information Officer Julie Habiger.

“We’ve got a long way to go before that — at least a couple of years,” Habiger said. “And then it would have to be funded as a capital project, because once you put it on the parks or open space list it’s got to be maintained, police have to patrol it and protect it. And we don’t even have any capital project cycle open. You’ve seen how full our plate is and how much is already allocated. You’d have to allocate the money for it.”

“But there is really strong community interest and council interest. That has always remained unwavering,” DPU Public Relations Officer Allison Majure said.

Before any such projects can be considered, the county must purchase the land from the National Forest Service, which it is entitled to do under the 2005 Pueblo de San Ildefonso Native Claims Settlement Act.

The Environmental Impact Statement for that purchase is nearly complete. The county must finish some land designations for parts of Rendija Canyon and Guaje Canyon for the State Historical Preservation Office. That is expected to take about three months.

“Once we do that, then the Forest Service will start working on the paperwork to transfer this property, which takes them about a year to 15 months,” Glasco said. “That’s if we can get them to work on it. That’s the problem we’ve had with the Forest Service, is that they’ve got other things going on. Their priority is taking care of the land they’ve got, not getting rid of it.”

Open Space Specialist Craig Martin is hoping to get Family YMCA Youth Conservation Corps workers in to restore the trail this summer. NPS has granted permission, but concerns about construction vehicle traffic may delay the project.

The reservoir has undergone some changes. DPU removed the gate tower, which would have required $300,000 to meet seismic standards plus additional money for other repairs.

There is currently no access over the spillway, either. The county owns a bridge and has a design for its placement, but insufficient funds remain to install it. The project requires a crane large enough to move a 32,000-pound bridge and a pad sturdy enough to support the crane.

Nonetheless, officials claim the new dam is designed to last.

A stepped service spillway in the center is expected to handle most flows. The steps help dissipate energy.
Auxiliary spillways on either side are covered in “sacrificial dirt” dredged from the reservoir. The rich soil should soon be covered with grass, but is not structurally significant during a flood. Underneath the soil is 10 feet of roller compacted concrete.

A stilling basin and riprap at the base of the dam will dissipate energy during a flood.

“It’s designed to take 44 percent of the probable precipitation in this canyon, which is huge: thousands of cubic feet per second,” Glasco said.