The Quail Creek dike, which broke Sunday unleashing floods in Washington County, was considered one of the relatively safe dams in Utah - even though it had foundation problems since it was built four years ago.
A Deseret News investigation, published last April, revealed that state and federal inspectors had rated as unsafe more than half of the dams above populated areas in the state or were unsure whether they are safe.Ironically, Quail Creek was not among them. It was listed among the minority of dams that inspectors felt was safe.
Richard B. Hall, state dam safety engineer, said Sunday that inspectors knew about a crack in the earthen Quail Creek dike and about problems with seepage in its foundation but felt corrective action being taken was sufficient to prevent a dam failure.
To show how relatively few dams in the state had received as clean a bill of health as Quail Creek, consider that the U.S. Army Corps of Engineers inspected 101 dams above populated areas in 1979 and 1980.
It rated 67 - or two-thirds - as "unsafe," and said more studies were needed to determine whether 27 others were safe. Those extra studies were never completed.
Quail Creek was built after the corps performed its studies.
But last year when the Deseret News asked Hall for an update about how he would rate the 167 dams now above populated areas, he still considered 27 as unsafe and was unsure about 63 others - meaning more than half were unsafe or questionable.
Hall said Sunday he had included Quail Creek among dams he felt were safe because it was new - only four years old - and its owners had tried to fix problems with the foundation.
"It had foundation seepage since it was built four years ago," Hall said. "But the owners had done a lot of grouting."
That is a method of pumping concrete into the foundation of an earthen dam to stop seepage. Without grouting, seepage can wash away dirt inside an earthen dam, weaken it and possibly lead to a failure.
Hall said that recent reports showed that grouting "had fairly well sealed up" the seepage. Hall said inspectors had also been monitoring a crack that had developed in the dam.
"We still don't know what caused the dam to fail. Unfortunately, the evidence is usually washed away downstream. But my boss (State Engineer Robert Morgan) and the governor are down there today inspecting it. I'm waiting to hear what they find," Hall said Sunday.
Quail Creek is the 69th failure or near-failure of a dam in Utah this century, according to records in the state engineer's office, which may be incomplete. The worst year recently for failures was 1983, when heavy runoff led to six dams failing - including the huge DMAD dam near Delta.
In the earlier Deseret News investigation on the safety of dams, officials said dams could be rated unsafe for one of three general reasons - structural problems, not having spillways large enough to handle potential runoff, or not being considered safe during earthquakes.
More than 90 percent of the dams that had been deemed unsafe by inspectors had spillways that are too small to handle possible runoff from storms or snowmelt. That means failure is not considered imminent but could happen in heavy storms or snowmelt.
For example, Mountain Dell reservoir above Salt Lake City has no spillway at all. City officials say they came within an hour during runoff floods in 1983 of seeing water go over its top. That would have damaged a water treatment plant and I-80 below it, and could have eroded the dam's toe and caused a failure that would have flooded much of eastern Salt Lake County.
Construction of the new Little Dell Dam above Mountain Dell is expected to allow officials to better manage runoff and avoid a dam failure.
A few dams were rated unsafe because of structural problems. If such problems are severe and dam failure considered likely, the state can order the reservoir drained and the dam breached to prevent storage. But notification requirements can stall that process for years.
For example, records show that the Birch Creek Dam No. 1 above Woodruff, Rich County, had severe problems for years while owners apparently ignored state orders to fix them.
Records show that the dam's owners were ordered in 1981 to leave the outlet at the dam unblocked (limiting how much water could be stored at the dam) because heavy seepage and a large sinkhole at the dam "raises considerable concern" about the dam's safety.
Records show that the reservoir was still filled for years - in direct violation of state orders. Most of the more major repairs ordered at the dam were finally completed by 1986. But a 1987 report said problems still remained with seepage and maintenance.
No dams in the state have yet been declared unsafe because of concern about their safety during earthquakes, mainly because the science of determining that is still in its infancy.
But inspectors worry that little information is available about the types of materials and compaction used to built many dams. That is of concern because many soils act like liquids during earthquakes, which could lead to a dam failure.
Numerous suggestions have been made on how to improve dam safety in the state. They range from giving dam owners funding or tax incentives to correct safety problems, forcing them to bring the dams up to code, hiring more inspectors or buying more high-tech equipment to improve dam inspections.
But all those options require money, and federal and state politicians have been trying to cut budgets.