Large precipitation events in 2023 and 2024 within the Pole Canyon fire scar caused high runoff and extensive debris flows within Nebo Creek. The flows caused significant damage to a fish barrier (drop structure) isolating an upstream population of Bonneville cutthroat trout from downstream nonnative Brown Trout. The flows damaged portions of the south barrier wall as water overtopped the structure and eroded the soil and concrete blocks. Woody debris mobilized by the high flows also created a jam which further redirected energy to the sides of the barrier wall. Some concrete blocks composing the north wall were also moved downstream. The barrier is still currently functioning to prevent upstream movement of Brown Trout, but its uncertain it can withstand another high flow event without failing.

1. Seal "bulged" barrier blocks with geofoam to help prevent erosion and promote stability 2. Install 2 concrete pads (120x82x7) in downstream portion of barrier (under falls) to prevent dissipate erosional forces that may undermine the barrier wall. Pads will also reduce pool depth downstream of the vertical barrier and further its effectiveness. 3. Seed and recontour disturbed upland sites.

High risk of barrier failure if another high precipitation event or abnormally high spring runoff occurs. If barrier fails brown trout will invade a successfully reproducing and isolated Bonneville cutthroat trout population.

2015. Utah Wildlife Action Plan 2015-2025. Project goals address major threats including "fire and fire suppression", "channel downcutting", "improper sediment balance", etc. and addresses threats to multiple WAP species, both aquatic and terrestrial. RANGE-WIDE CONSERVATION AGREEMENT AND STRATEGY FOR BONNEVILLE CUTTHROAT TROUT (Oncorhynchus clarki utah). Utah Division of Wildlife Resources, Publication Number 00-19, Salt Lake City, UT.

Several experts in range and fire science have identified the role healthy riparian systems play in wildfire dynamics by serving as fire breaks, safety zones, water sources, and burn out points. Numerous authors cite similar observations. Proposed practices will improve the riparian zone in the Nebo Creek watershed.

here are two current TMDL's that are impacted by this project. Spanish Fork River has one and Utah Lake has another (Nebo Creek is a tributary of the Spanish Fork). This project will not directly but will potentially move the system towards attainment and will prevent further degradation cause by wildfire effects.

Prior arch clearance when barrier was installed in 2022. Stream alteration permit still valid.

1. Seal "bulged" barrier blocks with geofoam to help prevent erosion and promote stability 2. Install 2 concrete pads (120x82x7) in downstream portion of barrier (under falls) to prevent dissipate erosional forces that may undermine the barrier wall. Pads will also reduce pool depth downstream of the vertical barrier and further its effectiveness. 3. Seed and recontour disturbed upland sites.

Fish populations are and will continue to be monitored on a 3-5 year cycle to assess the recovery of the fish populations following the fires of 2018. Barrier structure will be monitored for effectiveness and function twice annually.

Close partnership with U.S. Forest Service, Utah County.

Monitor barrier effectiveness and stability 2x annually, repair as needed in future years Numerous partners involved in post fire restoration and infrastructure repairs within the watershed following 2018 fires. Several prior WRI projects have been implemented within the Nebo Creek watershed to restore a functioning riparian and fisheries community. Previous projects included restoration of native cutthroat, addition of LWD/PALS, planting and reseeding riparian vegetation, etc.

The projects goal centers upon speeding the recovery of the riparian and aquatic community with the ultimate goal of restoring a self sustaining trout fishery for recreation and conservation purposes. Nebo Creek Canyon is a High Use Recreational area for dispersed camping, hiking, hunting and ATV'ing, these stream restoration efforts will speed desirability of the area for the public. Reseeding and reestablishment of watering areas and riparian forage will shorten post-fire rest periods on the two grazing allotments. Multiple grazing allotments within the drainage will/have benefitted from seeding, riparian restoration, and instream practices designed to limit channel downcutting and sediment retention.

09/23/2024

11/14/2024

2025

Two primary actions were completed to fix or stabilize the barrier walls and try and prevent future issues with high flows eroding the stream bed and the integrity of the side walls of the barrier. 1- Place two flat 120"x82"x7" cement aprons at the base of the barrier falls for the water to splash on and prevent the formation of a pool. 2- Inject/spray hydrophobic polyurethane geofoam into the open spaces on the side block walls of the barrier to help seal out water from getting behind the walls and try to secure or keep the walls from further settling and movement.

The high spring flows we had in spring 2024 resulted in some water getting behind/through the side barrier wall resulting in some of the lower blocks settling. We had to prevent any further settling and water from getting back into the wall. We also wanted to secure or try and hook the blocks together and we determine a possible solutions was to use expandible foam. We contracted with Utah Concrete Lifting and Repair to inject the foam into the cracks, open spaces and settling gaps of the side walls of the barrier on October 31, 2024. Just prior to that our heavy equipment crew and regional maintenance crew helped transport and install the two cement aprons into the stream bed below the barrier falls. We regraded and reseeded the disturbed area where the heavy equipment crew had driven their equipment to set the cement aprons and move materials around the barrier. The seed we used here was some leftover upland seed, mix 5969 that we had from a previous Diamond Fork Project. Very close proximity and and similar vegetation so this was a good fit for such a small need. Please see the photo presentation document in the images/documents tab which shows some before, during and after photos of the work completed on the Nebo Barrier.

UDWR biologists will monitor the stability of the barrier side walls and sealing of the cracks aimed to prevent water seepage to the back of the side walls resulting in further settling of the side walls. As of summer 2025 (post 2024-25 spring run-off) the injected foam appears to have sealed the side wall and no further settling has occurred and the barrier continues to function as designed. Assure that the vegetation continues to establish helping to secure the banks and areas surrounding the migration barrier. Also monitor fish populations above the barrier to confirm no invasion of the non-native brown trout population found further downstream. Supplement the Bonneville cutthroat trout population and Southern Leatherside chub population above the barrier as needed.