As built by Texas contractors, Chris J. Veesaert says the Santa Cruz dam was "unstable seismically." In a ten-year-type flood, the spillway would have been overtopped and the dam would likely have failed in a more serious flood. The Bureau of Reclamation redesigned it to be overtopped safely and built a "stabilizing arched buttress against the downstream face" to prevent failure from "erosion of the intensely-fractured granitic supporting abutment rock."
They couldn’t do anything about the silt that has accumulated at the bottom, reducing the capacity by 34%. When the district releases 8' of water for irrigation, the lake’s fishing dock is no longer usable. The irrigation district has been trying to increase the height of the dam to the level approved in 1929.
In 2000 Congress allocated $100,000 to study the sediment problem. John McCain protested it was an intolerable earmark.
In 2010 the Corps of Engineers awarded a $291,773.00 contract to the URS Group of Dallas for plans and specifications for the dam restoration project.
When I attended the local ditch meeting a few years ago, the majordomo was optimistic it would soon be shovel ready, waiting for funding.
He also reported on the potential problems caused by Chimayó’s tainted ground water. People in the audience began volunteering information that people up there had put their new well next to the dam and was sucking 60% of its water from the dam they still refuse to pay for.
The 1938 Rio Grande Compact between Colorado, New Mexico and Texas limited even more the amount of water people here could use. The dam is no longer simply a source for irrigation water. It’s now part of the regional network that controls the amount and quality of water flowing to Texas.
Whatever its faults and costs, it has to be maintained.
Notes:
US Department of Interior. Bureau of Land Management. Santa Cruz Lake Recreation Facilities Rebuild, Environmental Assessment.
Veesaert, Chris J. 2002. "Addressing Hydrologic Inadequacy" in Dam Maintenance and Rehabilitation edited by J. A. Llanos, J. Yague, F. Sanz de Ormijana, M. Cabrera and J. Penas.
Photographs:
1. Santa Cruz Lake, 14 February 2012; the boat ramp is in the left center.
2. Santa Cruz dam face, 16 February 2012; the buttress addition is on the left.
No comments:
Post a Comment