Specifications include, but are not limited to: This one mile section of Pack Creek was completely burned in the 2021 Pack Creek fire. Since the fire, Pack Creek has experienced over 20 significant debris flows up to 1,000 cfs that have incised the channel vertically and laterally. Because of the monsoonal precipitation regime in the area, the channel dimensions (high water mark, thalweg, floodplains, benches, etc.) are changing every week during the summer season. Not only is the USFS concerned about the erosion of the channel, but the vertical incision is cutting into the local unconfined aquifer. Because this is cutting into the unconfined aquifer layer, we are starting to see an increase in baseflow and the indirect dewatering of the water table. The estimated rate of increase in baseflow since the 2021 fire is approximately 0.06 CFS or 38,000 gallons per day. As a result of the loss in groundwater, there may be an indirect effect to the riparian vegetation that has adapted root depths to the previous water table elevation. As riparian vegetation rooting depth requirements are drastically changed, vegetation successional trends might convert to a more facultative upland state. This project will tie into NRCS EWP efforts at the USFS boundary to form a complete Pack Creek restoration project. During the emergency implementation work for Pack Creek, the USFS installed three sections of rip-rap that served the purpose of protecting the road for these two years, but are no longer functioning as debris-flow undercut the rip-rap banks, and sweeps the large rock downstream. USFS also tested a few steel nets anchored into the banks with holding capacities beyond 3 tons. USFS Hydrologist, Daniel Lay, measured every debris-flow event that has happened in Pack Creek and have noted that events that produce up to 1,000 CFS can easily move car-sized boulders and trees without much problem.
