9593

• UCREFRP Catalog Number: 9593
• Author: Tetra Tech Inc.
• Title: Concept Development Report Hartland Diversion Dam Fish Passage Structure Delta, Colorado.
• USFW Year: 2000.
• USFW - Doc Type: Grand Junction, CO.
• Copyright Material: NO

of the fish passage structures, under low flow conditions of 350 cfs, is to lower the water

surface elevation by .07 feet for Alternatives I and II and .05 feet for Alternative III. The net

effect of the fish passage structures on water surface elevations, for flows above 350 cfs,

decrease as flows increase for Alternatives I and II. The net effect of the fish and boat passage

on water surface elevations for Alternative III increase as flows increase above 350 cfs.

However the water surface elevations for Alternatives III all remain well above the minimum

operating levels.

7.2 Fish Passageway Operations and Swimming Ability

All three alternatives are developed using the same criteria for fish swimming ability.
For flows that are less than 11,600 cfs, velocities and depths for Alternatives I and II are in the
acceptable range. The fish ladders in Alternatives I and II become inundated when river flows
exceed 11,600 cfs, at which time fish passage may be possible directly over the dam along the
riverbanks.
Flow characteristics for Alternative III vary not only as a function of river flows but also
as a function of location in the passageway. When the Gunnison River is at 350 cfs, depths
range from 1.7 to 4.5 feet and velocities vary from 4.6 to 0.4 fps in the chutes and pools,
respectively. As flows increase so do depths and velocities. At 1200 cfs, depths range from
2.6 to 5.5 feet and velocities range from 4.8 to 1.1 fps in the chutes and pools, respectively.
Above 1200 cfs velocities in the center of the river start to exceed the limits established for fish
passage at which time it is anticipated that the fish are able to pass over the structure along the
riverbanks. Thus during the critical pre-runoff spawning period in late April, modeled at 3000
cfs, the river banks are accessible for fish passage.
Alternative III design is very similar to the water diversion/fish passageway structure
built on the Yampa River for the City of Craig. Flow characteristics and river dimensions of the
Yampa River are very similar to the Gunnison River at the Hartland diversion structure.

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