Bend Hydro Dam impounds the Deschutes River forming Mirror Pond–a small, shallow lake, which is currently about X acres in size and the lake is used by an unknown number of local residents for recreation.
Mirror Pond has filled with between X,000 and Y,000 yd³ of sediment.
Alternatives
A: No Action
B: Retain the dam and sluice
- Send the sediments down river
- Divert sediment into an irrigation canal
C: Retain the dam and dredge
- remove all sediment
- from main pond
- from entire pond
- remove minimal amount of sediment
- from main pond
- from entire pond
D: Retain the dam and channel restoration/sediment maintenance program
- add fish passage and fish screens
- add fish/people passage and fish screens
E: Remove dam without clearing ancient channel
- No dredging
- Minimal dreading
F: Remove dam dreading ancient channel
- Diverting the river
- Without diverting the river
Alternative A: No Action
The dam would be left in place under this alternative and Mirror Pond would continue to slowly fill with gravel. The dam would not have fish ladder and would continue to be a barrier to fish and people. The pond would continue to be used for recreation purposes, but the existing sediment would not be removed.
Alternative B: Retain the dam and sluice
The dam’s sluice gates and sluiceway would be used to drain the pond and erode the sediment in the river’s natural channel behind the dam. The naturally occurring flows of the Deschutes River would erode the sediment in its ancient channel. It may be necessary to use heavy equipment to clean the area of the forebay behind the sluice gates. Because operational sluice gates in a normal dam function, the maintenance of these gates does not require any permits.
Downstream, the Tumalo Irrigation District’s dam would have its sluice gate open and all stop-boards removed. The intake to the Bend Feed canal must be closed. The spawning beds near the First Street Rapids may need to be covered prior to the sluicing process.
At the North Dam, for Alternative B1: all intakes to the irrigation canals are closed and the slurry is washed downstream over the spillway. For Alternative B2: the intake to the North Unit canal is open and the slurry is transported in the canal to a point beyond the recent lining where it is busted out of the canal and allowed to settle in the high desert.
C: Retain the dam and dredge
The dam would be retained and the pond would be dredged in a similar fashion as it was in 1984. Alternative C1a would remove all the sediment from the main pond; Alternative C1b would remove all sediment from the entire pond. Alternative C2a would dredge a minimal amount of sediment from the main Mirror Pond (this is what was done in 1984); Alternative C2b would be the same as C2a with a little additional dredging above Galveston Bridge.
D: Retain the dam and channel restoration/sediment maintenance program
E: Remove dam without clearing ancient channel
F: Remove dam dreading ancient channel
reservoir sediments.