Large precipitation events in May 2023 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. Rebuild and stabilize impacted barrier walls. 2. Stabilize upstream and downstream riparian areas to prevent future lateral migration of stream as it interfaces with barrier 3. Reseed/revegetate disturbed area

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 cutthroat 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.

There 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. The project will also directly benefit water quality in several ways, including the following: 1. Prevent channel downcutting and promote aggradation of sediments in entrained reaches. 2. Reduce sedimentation delivered further downstream (i.e. Spanish Fork River, Utah Lake, Jordan River and The Great Salt Lake) 3. Trap/filter sediment, nutrients, and contaminants thus prevent (reducing) its movement downstream. Riparian seeding and vegetation also can remove/alter organic nutrients through processes such as denitrification, absorption by clays, etc.

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

Use excavator to rebuild/modify barrier walls that failed during high flows. The barriers is primarily composed of large concrete blocks with supporting boulders for flow deflection and erosion control. It is anticipated portions of the barrier may also be relined with erosion control cloth. Disturbed areas will be seeded with an appropriate seed mix.

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.

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.

10/16/2023

10/25/2023

2024

Large precipitation events in May 2023 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 washed concrete blocks away and downstream. The south barrier wall was rebuilt using both new blocks and salvageable existing blocks washed downstream. The wall was raised one block higher (2 feet) and extended downstream 12-15 feet. This was accomplished by purchasing and installing 58 additional 2'x2'x4' blocks. The enlargement of the south barrier wall and extending the north barrier walls downstream should prevent the river from overtopping or eroding behind these walls. Photos of the before and after are likely the best explanation of what needed to be done and what was completed.

The large blocks were purchased and transported to the barrier site in October 2023. The UDWR heavy equipment crew arrived with trachoe, frontend loader and dump trucks to do the work October 16-25, 2023. Additional "deadman anchors" were used to help secure and stabilize both the southern and northern walls as part of the reconstruction efforts. Disturbed areas were reseeded upon completion of the barrier construction. Please see addition after photos in images/documents.

Continue to monitor the effectiveness and integrity of the barrier to assure no invasive species make it up into Nebo Creek and it's tributaries and compromise the restoration of Bonneville Cutthroat Trout populations. Electrofishing surveys will be conducted in 2023 and 2024 and following years to confirm effectiveness of the barrier. Any future issues with the barrier will be assessed and repaired if necessary. Supplemental BCT stocking will continue in future years as needed. Assessment on other native species (Southern Leatherside Chub) will also be conducted in association with the BCT restoration efforts.