Improving Safety at Wapama Falls Footbridge
The popular Hetch Hetchy Reservoir Trail leads from the O'Shaughnessy Dam around the north shore of the reservoir and on to many day hiking and overnight-backpacking destinations in the park. Wapama Falls is located via a 2.5 mile hike along the trail and is fed by Falls Creek. A series of five footbridges cross in front of the cascading falls allowing backpackers and day hikers access to miles of trails and the destinations beyond. However, during spring run-off conditions and heavy rain events, the westernmost portion of the footbridges can be inundated with water from the falls and may become impassible. These conditions can cause safety hazards for many visitors and results in them having to make a decision about whether to proceed through the waterfall spray or turn around, which can cut short plans for their hike, or causing home-coming backpackers to hike an alternate approximately 20-mile route to return to their vehicles. The second option is for hikers to proceed across the bridge at great risk to their wellbeing which resulted in two fatalities in 2011 and one in 2017 when hikers were swept off of the footbridges.
This project will replace the westernmost of the five footbridges that crosses Falls Creek at the base of Wapama Falls and reroute it south of the existing bridge section to alleviate the dangerous inundation conditions that are sometimes experienced in this section during high flows. This realignment will increase visitor safety by reducing the potential for bridge inundation and increase the bridge's visibility from the western approach, so that visitors can better assess the crossing conditions and any associated risk before proceeding. The problematic section of the Hetch Hetchy Reservoir Trail is located at the 65-foot westernmost span of the five footbridges that crosses Falls Creek approximately 2.5 miles east of the O'Shaughnessy Dam Trailhead. The westernmost bridge span would be replaced by two new, re-routed spans that would be approximately 120 feet in length combined (two spans are needed to bypass the fall spray zone and associated change in alignment). The westernmost abutment would be moved approximately 25 feet to the west, and the span would run approximately 40 feet to the south of the current alignment outside the area of hazardous water flow. The new abutments and supports will be within the boulder-strewn Falls Creek drainage. The new bridge sections would be designed and fabricated to match the existing foot bridges. Trail crews would construct a small section of trail (roughly 10 linear feet) that would reroute the trail to the new bridge abutment. Materials will be transported by either helicopter, boat, stock, or by foot. Following completion of the reroute, the park would remove the existing 65-foot bridge section and restore to natural conditions the 25-foot section of trail leading up from the west to the existing bridge. Work would be completed using standard trail construction/maintenance methods in designated wilderness
This project is in wilderness and has had an MRA completed
The purpose of this project is improve the safety at Wapama Falls.