AMERICAN FORK CANYON — The North Utah County Water Conservancy District must develop a restoration plan for the sediment-polluted American Fork River and explain why it failed to notify regulators about the Aug. 20 Tibble Fork Dam release that killed fish in a 2-mile section of the river.

Those conditions are among several contained in a compliance order issued by state water quality regulators on Wednesday, as well as a notice of violation that accuses the district of discharging heavy metal pollutants into the river that harmed public health, wildlife, fish and the aquatic ecosystem.

In addition, the department's Division of Water Quality asserts the water district failed to meet Army Corps of Engineers and agency permit conditions and failed to immediately report the incident to the state.

“The release had a significant effect on a popular fishing area and an important water source for local irrigation companies,” said Walt Baker, the Division of Water Quality's director. “We still don’t know what the long-term impacts to aquatic life and other uses of the river will be from the deposition of a significant quantity of sediment in and along the river.”

The district was in the midst of a $7.3 million rehabilitation project of the upstream Tibble Fork Dam in partnership with the U.S. Department of Agriculture's Natural Resources Conservation Service, draining the small reservoir and raising the level of the dam to ensure it meets modern engineering standards.

As the last of the water was beginning to leave the reservoir, inflows from a mountain stream cut a wide swath of metal-laden sediment, washing it into the American Fork River below.

While officials said they expected some release of the sediment, which contained arsenic and lead from legacy mining operations, the amount of earthen material caught them off guard.

Related:

State biologists probing fish kill from Tibble Fork dam reconstruction

State wildlife biologists surveyed fish populations in the American Fork River after thick sludge caused a fish kill. The USDA's Natural Resources Conservation Service began a rehabilitation project at Tibble Fork Dam in June, releasing sediment.

Kim Shelley, the division's surface water section manager, said the water district will be required to quantify the amount of material released into the river and the concentration of the metals.

Baker said the district must now prepare a comprehensive cleanup plan for the American Fork drainage that details how the sediment will be removed and what steps will be taken to protect public health and wildlife.

The district must also develop a comprehensive monitoring plan that includes a demonstration that restoration efforts are effective over the long term.

“We want to ensure that the water quality of the American Fork River is restored and that residual sediments from the release don’t degrade the river or threaten public health or aquatic life in the future,” he said.

"Most importantly, we want to make sure that this kind of incident doesn’t happen again."

The water district, which did not have anyone available to comment Wednesday, has 30 days to respond to the state's assertions.

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