PROJECT LOCATION:
This project is located on Catherine Creek, in the City of Union at the Swackhammer irrigation diversion structure.  The project legal description is T.4S., R. 40E.,  section 19, ne¼ of ne 1/4. (see attached map).

PROJECT OBJECTIVES:
•Establish year-around fish passage at the Swackhammer diversion structure
•Stop northward Catherine Creek channel migration
•Reduce streambank erosion, bedload additions and stream sedimentation
•Reestablish somewhat natural bedload transport through the diversion structure and downstream of the structure
•Reduce the flood potential aggravated by construction of existing fish weir and accumulation of mid-channel bedload

PROJECT DESCRIPTION:
Introduction:  This project is remedial action needed to correct fish passage, erosion and bedload aggradation problems not completely addressed or aggravated by the replacement of the old Swackhammer diversion structure (1995 OWHP, BPA, ODFW, NOAA).  The structure does not meet current fish passage guidelines, has caused severe bank erosion and does not facilitate diversion of water into the Swackhammer ditch.  The project proposes to retrofit the diversion structure, reinstall the fish screen, install a combination of grade control structures (cross vanes and J-hooks), revegetate streambanks and reshape the irrigation ditch.

Specific Actions: Several collective actions are prescribed and necessary to correct the fish passage, erosion, water quality, landowner damage and water diversion problems.  The BOR has prepared preliminary designs for retrofitting the structure and installing in-channel rock structures (attached), and has made recommendations for work on the fish screen and ditch that are necessary in addition to modifications to the structure.  

Alternative actions included elevating the uppermost weir in the existing structure, lowering the headgate, lowering the ditch and fish screen, constructing additional walls in the weir structure and rock structure installations to direct flow.  BOR flow analysis indicates the structure cannot be elevated due to potential flooding problems above the structure and because this would require even more extensive and expensive modifications to the structure and downstream to meet fish passage requirements.  

The final BOR design requires retrofitting the existing structure walls, installing additional walls, lowering the fish screen and ditch, gravel bar removal and rock structure installation (see designs).   The ditch and fish screen elevation be lowered approximately one foot to draw water down the ditch eliminating the need for the irrigation company to place checkup boards on the structure.

Specific actions are:
•Install two additional concrete weir walls within the existing structure to reduce drop at each weir to approximately 8 inches.
•Modify the three existing weirs by filling in existing 17' wide flow notches and recutting 6' wide flow notches for fish passage closer to the headgate.

•Remove the mid-channel gravel bar and use material to rebuild streambank along the north side of the channel.  This will require 10-12 feet of extension pipe on the end of the fish return pipe from the fish screen.
• Install two J-hook structures and one cross channel vane to direct flow through the middle of the structure and down through the middle of the channel below the structure (see drawings).
•Re-install the fish screen one foot lower to increase flow down the ditch.
•Lower and reshape the ditch (drop ditch bottom approximately one foot for a distance of 400 feet.  
•Relocate (below deepened ditch) a City of Union water line that crosses the ditch just below the fish screen.
•Reseed disturbed ground.

Existing vegetation on the north bank will be maintained as much as practical requiring little if any artificial revegetation actions.  Flow will be diverted away from the reconstructed streambank allowing willows to naturally reestablish which is predicted given what has occurred on the mid-channel gravel bar.

All construction associated with the diversion structure and channel reconstruction will be contracted.  ODFW will reconstruct the fish screen and assist with excavation for the water main relocation (if timing coincides with fish screen reconstruction).  City of Union Public Works Department will relocate (or contract for work) the water main.  The Swackhammer Ditch Company will reshape and deepen the ditch.