Tuolumne River Report - U.S. Fish and Wildlife Service

TUOLUMNE RIVER TECHNICAL ADVISORY COMMITTEEHABITAT RESTORATION PLAN FOR THE LOWER TUOLUMNE RIVER CORRIDORCHAPTER 4orchard, and this bend will be recontoured to amore gentle bed and revegetated to minimize futurebank erosion.Fluvial geomorphic, riparian and biologicalobjectives of the project will be monitored toassure project performance success. The totalestimated cost for SRP 9 implementation is$2,700,000.For additional details, the complete projectconceptual design is available upon request.4.5.4. Special Run Pool 10 ChannelRestoration ProjectBackgroundAt SRP 10 aggregate extraction created a 400 ftwide by 36 ft deep in-channel pit, and eliminatedthe large point bar and floodplains on the northbank (Figure 4-6). Restoring SRP 10 in conjunctionwith SRP 9 will restore bedload transportcontinuity through this reach, which can be usedby the river to build and maintain dynamic gravelbars (available for chinook habitat).SRPs 9 and 10 are the largest known predatorisolation projects on the Tuolumne River, andthus the most expensive to restore. SRP’s wereidentified as limiting factors to chinook salmonsurvival, because the unnaturally wide channeland deep water conditions offer suitable habitat tonon-native largemouth and smallmouth bass, andthe native Sacramento squawfish, all of whichprey on juvenile chinook salmon. Because amajority of chinook spawning in the TuolumneRiver occurs upstream of this location, mostjuveniles must pass through this reach. Reducingpredation should therefore increase TuolumneRiver smolt production.Project ObjectivesSpecial Run-Pool 10 (SRP 10) is located one miledownstream of Fox Grove County Park, 9 mileseast of Modesto, and extends from RM 25.2 to25.6. Specific objectives of the project are:• Reduce/eliminate habitat favored by predatorybass species, and replace with high qualitychinook salmon habitat.• Restore channel and planform morphologyscaled to contemporary and future sediment andhydrologic regimes.• Restore sediment transport continuity andeliminate bedload impedance reaches.• Revegetate reconstructed floodplains andterraces with native woody riparian species,planted on surfaces designed to inundate atdischarges appropriate for each species/serieslife cycles.Project DescriptionThe proposed treatment will fill most of the pit,and re-establish an alternate bar morphologythrough the reach. The project design is to fill thepool primarily from the north bank to createfloodplain and native riparian habitat. The lowwater channel in SRP 10 will be reduced to amaximum width of 100 ft, and will flow alongwhat is now the south bank. The 1997 floodcaused damage to the dike on the south bank onprivate property adjacent to SRP 10, and willrequire repair during the construction phase toensure project longevity. The outside of themeander (curving north) along the south bankwill be recontoured with a widened floodplain.The proposed channel topography will includethree pool /riffle sequences (max pool depth =10ft). SRP 10 will require 293,000 yd 3 of material,substantially more than SRP 9 because of thegreater pool depth.The proposed design will also re-establish plantseries patterns identified during the riparianinventory, including willow and alder stands,Fremont cottonwood, and valley oaks, planted onsurfaces successively distant and at higherelevations, respectively, relative to the low waterchannel. Floodplains will be designed to inundateat approximately the post-regulated 1.5 to 2.5-yrflood. Cluster planting will create a more naturallook to the site, ease watering and maintenance,and increase habitat diversity. Irrigation will berequired for two summer seasons. Revegetationmaterials will come either from on-site sources(valley oak seeds, willow cuttings, cottonwoodcuttings), or from local nurseries (sedges, alder,and Oregon ash).Fluvial geomorphic, riparian and biologicalobjectives of the project will be monitored toassure project performance success. The totalestimated cost for SRP 10 implementation is$4,657,000.For additional details, the complete projectconceptual design is available upon request.162