Construction of the Trinity River Hatchery Channel Rehabilitation and Coarse Sediment Augmentation Project (Phase 1) was completed in August 2006 |
 Spawning and rearing gravels in the area immediately below Lewiston Dam and Hatchery are seriously depleted. |
The final design for the area includes vegetation removal, channel widening, construction of deeper pools, as well as the addition of over 2,500 tons of coarse sediment. |
Construction was completed before Labor Day 2006. |
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The Trinity River Restoration Program (TRRP) completed placement of approximately 2,500 tons of coarse sediment immediately downstream of the Lewiston Dam, near the Trinity River Hatchery, August 2006.
The TRRP worked with the Bureau of Reclamation, the U.S. Forest Service (both members of the Trinity Management Council), and other TRRP partners for several years in order to plan and implement 2006's placement of coarse sediment (1/4 to 5 inch diameter gravel). This is one of several gravel augmentation sites identified in the Trinity River Flow Evaluation Report and the December 19, 2000 Record of Decision where the river channel has degraded and where additional coarse sediment input is needed. Post project improvements in river substrate and hydrodynamics will increase useable spawning habitat as well as spawning and egg incubation success, and will provide quality nursery habitat to increase survival of recently emerged egg sack fry and juvenile steelhead and salmon. Dramatically increased use of the area by spawning salmon was seen immediately in the fall of 2006.
Illustrated map of the project site with annotations
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| click to enlarge [PDF] |
Implementation of the 2006 project included: [1] removal of existing riparian vegetation along the riverbank to access the project site, [2] excavation, redistribution and/or removal of approximately 6,900 cubic yards of existing riverbed and bank material, [3] mechanically re-shaping the river channel, including lateral channel widening of specific segments, and [4] introduction and placement of approximately 2,500 tons of washed coarse material originating from the Trinity River basin. Excavated material was moved upslope to build a vehicle turn-around and parking lot for anglers.
Next year, the TRRP plans to complete this phase of the project with addition of another 6,500 tons of gravel. Because the dam has eliminated movement of coarse sediment through the river, supplementation, and maintenance of coarse material will be needed into the future at this site and will be provided as funding is available.
The Finding of No Significant Impact was signed on May 31, 2006, by the Program's Executive Director. Signature of this document allowed the Forest Service to immediately proceed with the project as described in the EA. The following link (AdoptEA&Response.pdf) contains the following documents: (1) the Forest Service EA, (2) additions to meet National Environmental Policy Act and Reclamation environmental compliance guidelines, and (3) a memorandum that details the circumstances surrounding the need for adoption of the Forest Service EA as one that met all of Reclamation's requirements.
Project Area Photos
Pre and Post Project Overview:
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Just post gravel introduction (8/14/06)
New gravel replenishes the supply just downstream of the of the dam. (Click photo for full size image.)
