7884

• UCREFRP Catalog Number: 7884
• Author: Hydrosphere Resource Consultants.
• Title: Reconnaissance Evaluation of Yampa River Diversion Structures.
• USFW Year: 1995.
• USFW - Doc Type: Boulder, CO.
• Copyright Material: NO

IL?
Chapter 3
Evaluation of Diversion Structures
DESCRIPTION OF STRUCTURES EXAMINED IN FIELD
Each of the fifteen structures which were examined first-hand during field reconnaissance
are described below in an upstream to downstream order. All diversion structures considered
as part of this investigation are described in summary form in Appendix F. Photographs of
selected structures are provided in Appendix E.
' Marshall-Roberts Ditch

11

I
1
r

The Marshall-Roberts Ditch is located upstream of the Town of Hayden well above
occupied and designated critical habitat. The diversion structure consists of a temporary berm
constructed of gravel alluvium blocking roughly 75 percent of the river channel. It extends from
the downstream end of an island near the left bank (river left) and angles upstream to the right
bank. The structure contains a constructed low-flow notch at the left end of the gravel berm. The
berm diverts flow into a side channel which lies between the left river bank and the island. The
ditch headgate lies on the left river bank at the downstream end of this side channel. The side
channel is blocked with a smaller gravel dam below the headgate location, where the water
would normally return to the main river channel. The main gravel berm causes approximately
a two-foot drop in water surface and it appears that partial annual re-construction is necessary.
The potential for impact to Colorado squawfrsh from the Marshall-Roberts Ditch is
probably low, due mainly to its upstream location. The removal of material from the channel
during annual maintenance and construction has caused a large area of braided channel to form
downstream of the berm and has resulted in some disturbance of the adjacent riparian island.
This annual disturbance causes substantial impact to local benthic invertebrates and probably
displaces some resident fish. The broad downstream approach channel may make passage
moderately difficult for any fish species trying to move upstream through the structure during low
flow periods.
Colorado Utilities Ditch and Pipeline (Hayden Generating Station)
This diversion is well upstream of occupied and designated critical habitat for the
endangered fishes. Water withdrawal is accomplished by pumps located in an artificial
embayment on the left bank of the river just downstream of the Highway 40 bridge east of
Hayden. The embayment is roughly 300 feet long by 100 feet wide, so the pump intakes are
located well away from the main river channel. There are no structures within the river channel
directing flows into the embayment nor is there any evidence of recent instream construction
activity associated with this diversion.
The potential for this diversion structure to affect endangered fishes is probably very low
due to its upstream location and the fact that it does not have any instream features. Because it is
a permanent facility requiring little or no annual maintenance, its impact on riverine and riparian
habitat is also low.
3-1