December 12, 2014 | 8:00 am
Explore Oklahoma’s dams with StateImpact’s interactive map detailing their age, type, owner, hazard classification and reported failures.
Oklahoma has the fifth-largest dam inventory in the United States. Ownership of the 4,700 dams is largely split between government agencies and private entities, including individual owners and other organizations like homeowner’s associations.
Dam failures are exceedingly rare, but they do happen. And while there’s no comprehensive accounting of such events, at least 12 dam failures have been reported in Oklahoma, according to a database maintained by Stanford University’s National Performance of Dams Program.
Oklahoma’s dams are old, and while age is a major factor in potential dam failures, one of the biggest problems, state dam safety officials say, is outdated risk assessments.
Like much of the state’s water infrastructure, the bulk of Oklahoma’s dams were built before the the 1970s, when Oklahoma first started classifying its dams based on the potential hazards a failure would pose to people and property.
- Low – no loss of life, minimal economic loss
- Significant – no loss of life, appreciable property loss
- High – one or more structures with potential loss of life, excessive property loss
For many dams in Oklahoma, that initial ’70s survey is the one-and-only time their risk has been assessed. The potential hazard, however, has changed because Oklahoma itself has changed — There are houses, businesses, roads and people where there weren’t before.
Dam safety is expensive and time consuming. Re-evaluating a dam’s potential hazard starts with aerial surveys, population mapping and risk calculations, and on-the-ground site visits. Federal funding is erratic, and Oklahoma’s state funding for dam safety is well below the national average — $180,990 compared to $688,000 in 2012 — data from the Association of State Dam Safety Officials show.
Oklahoma also ranks poorly in dam safety staffing, ASDSO data show. In 2013, the State of Oklahoma had four full-time equivalent dam safety staffers. That’s about 1,148 dams per staffer — more than four times the national average of 199.
Most high-risk dams require Emergency Action Plans that spell out potential dangers and the best course of action to save lives and minimize property loss if an emergency occurs. In Oklahoma, almost all of the dams required to have an EAP have one, and while the state’s compliance on this exceeds the national average, many of those emergency plans are based on decades-old hazard classifications.
In Oklahoma, most of the 12 reported failures occured at low-hazard dams. Only two high-hazard dams have failed, NPDP data show. The most recent occured on Nov. 8, 1986 at the Cedar Lake Dam near Union City, owned by the Western Sportsman Club, which failed due to seepage and related internal erosion known as “piping.”
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