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Tibble Fork Dam Rehabilitation

NRCS Construction Update on Reservoir Bypass ChannelConstruction on Reservoir Bypass Channel

The North Utah County Water Conservancy District has designed and is having the contractor build a reservoir bypass channel to keep the stream from eroding sediments deposited in the basin.  The contractor began construction on the channel Aug. 24, 2016 and has been working around the clock to get it in place.  We expect the channel to be functional Aug. 26, 2016.  The bypass channel will allow the American Fork River to run around the sediment pool in the basin of the reservoir and out the outlet of the dam without eroding sediment into the stream.

Utah Department of Wildlife Resources update on Fish kill in American Fork Canyon - Aug. 26, 2016 (docx)
NRCS American Fork River Reconnaissance 8-25-2016 (PDF, 29.6 MB)

For information regarding water quality sampling and data please visit the State of Utah DEQ website at tibble.utah.gov

 

PUBLIC NOTICE UPDATE:

THE REHABILITATION OF TIBBLE FORK DAM REQUIRES THE TOTAL DRAINAGE OF THE RESERVOIR IN ORDER TO START WORK ON THE DAM’S EMBANKMENT.

USERS OF THE AMERICAN FORK RIVER BELOW TIBBLE FORK DAM AND EXTENDING TO APPROXIMATELY THE TIMPANOGOS MONUMENT WILL SEE TEMPORARY ELEVATED LEVELS OF SEDIMENT IN THE WATER.

BEST MANAGEMENT PRACTICES ARE INSTALLED AS MUCH AS PRACTICABLE TO HELP MINIMIZE SEDIMENT TRANSPORT IN THE STREAM FLOW BELOW THE DAM.  ALL DISCHARGES ARE IN ACCORDANCE WITH THE ENVIRONMENTAL ANALYSIS, PERMITS AND LAWS.

THE DURATION OF THESE DRAINAGE FLOWS ARE EXPECTED FOR APPROXIMATELY 48 HOURS STARTING AUGUST 19, 2016.

 

Tibble Fork Dam will be drained and under construction
June 13 to December 31, 2016

  • The reservoir will be drained through December 2016.
  • Traffic can still flow through the area with caution.
  • Half of the north parking lot will be open.
  • Cabin owners will have access to their properties.

Tibble Fork Dam Rehabilitation Public Notice (PDF, 143 KB)
Tibble Fork Dam Rehabilitation Project Summary Sheet (PDF, 189 KB)
 

Notes:

  • It is estimated that 10’vertical feet equals 50 acre-feet of water.  It is also estimated that the max depth of the reservoir at this time may only be 7’ deep.
  • Observations of water depth in front of the trash rack or spillway appears to be very shallow for several feet horizontally. Perhaps 10’ vertical is more than necessary for equipment and needed work to be accomplished. As reservoir reaches this elevation engineers will be contacted to determine if water elevation drop can be stopped at less than 10’.
  • Continual monitoring of flows, filling and draw-down will be important prior, during and after drilling.
  • It is beneficial for the fish survival in the reservoir to remain as deep as possible.

Project Description

The Natural Resources Conservation Service (NRCS) is analyzing alternatives to rehabilitate Tibble Fork Dam located on United States Forest Service Uinta-Wasatch-Cache National Forest property. NRCS performed an assessment of Tibble Fork Dam in 2004. The 2004 assessment concluded that Tibble Fork Dam does not meet current NRCS and Utah State Dam Safety regulations and engineering standards for a high hazard dam (potential “Loss of Life”). The purpose and need of this project is for Tibble Fork Dam to meet current USDA-NRCS and Utah State Dam Safety regulations and current engineering standards. It would also continue to provide current benefits for the primary authorized purposes of flood prevention and sediment retention with secondary benefits of recreation and irrigation water storage.  Stabilizing the existing dam structures would address the risk of loss-of-life and flooding associated with a dam failure because the dam is not meeting current safety criteria.

NEPA Analysis

This project is being partially funded by the NRCS Small Watershed Rehabilitation Amendments (PL 106-472) which authorizes funding and technical assistance to rehabilitate aging flood control dams built under the Small Watershed Program (PL 83-566). NRCS, as the lead federal agency, is initiating NEPA analysis in the form of a Supplemental Watershed Plan and Environmental Assessment to analyze impacts to the natural and human environment from this project. The Environmental Assessment will comply with the Council on Environmental Quality’s regulations at 40 CFR Parts 1500-1508 which require an evaluation of potential environmental impacts associated with federal projects and actions. This project is located within the boundary of the Uinta-Wasatch-Cache National Forest and the United States Forest Service is a cooperating agency.

Current Status

The NRCS has completed the Final Supplemental Watershed Plan-Environmental Assessment (Final Plan-EA) describing the proposed rehabilitation of the Tibble Fork Dam.  The Final Plan-EA presents the alternatives analyzed, potential impacts to the environment, and the Preferred Alternative for the project.  The NRCS Utah State Conservationist has decided that a Finding of No Significant Impact is approved for the Preferred Alternative (Dam Rehabilitation Alternative).

Contact Information

For further project information please contact:

Norm Evenstad - NRCS
Wallace F. Bennett Federal Building
125 S. State Street – Room 4010
Salt Lake City, UT 84138-1100
Phone: 801-524-4569
Fax: 801-524-4403
norm.evenstad@ut.usda.gov


Project Documents

Finding of No Significant Impact

Tibble Fork Finding of No Significant Impact (PDF, 90 KB)

Final Plan - EA

Tibble Fork EA Final Plan (PDF, 144 MB)

Draft Plan - EA

Tibble Fork Draft Plan EA Total Report (PDF, 114 MB)
Tibble Fork Draft Plan EA Report (PDF, 1.73 MB)
Tibble Fork Draft Plan EA Appendix A (PDF, 576 KB)
Tibble Fork Draft Plan EA Appendix B (PDF, 16.2 MB)
Tibble Fork Draft Plan EA Appendix C (PDF, 13.3 MB)
Tibble Fork Draft Plan EA Appendix D (PDF, 9.05 MB)
Tibble Fork Draft Plan EA Appendix E (PDF, 74 MB)

Other Documents

Scoping