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

Evaluation of Diversion Structures I
Williams Ditch I
The Williams Ditch is located upstream of the Town of Hayden above occupied and
designated critical habitat. The diversion structure consists of a two part temporary instream
structure of gravel alluvium fully blocking the river and angling slightly upstream from river
left to river right. The structure is split into two parts by a small island; the main portion fully
blocks the right river channel while the left portion contains a gravel-lined low-flow channel.
Flow is diverted into a short ditch and headgate on the left bank. The gravel diversion on the
left side causes about a 1-1/2 foot drop in water surface and appears to be re-constructed '
frequently but not annually (it -a re-constructed in 1994). The main channel berm is re-
constructed annually, usually during August, by pushing gravel alluvium into place.
Frequent re-construction practices have created a large braided channel area downstream ,
of the diversion structure, though the left channel appears to remain navigable by watercraft
and fish. Like many other diversion structures built up of river alluvium, the most significant
impact of this structure is probably to benthic organisms. Other impacts may result from fine
sediment that enters the water column during construction. Based on conditions observed during
August, 1994, passage at this structure is possible and it is believed that it would usually not
present a significant obstacle to endangered fishes; however, there is a moderate amount of habitat
disturbance associated with it.
Walker Irrigating Ditch
This diversion structure was visited in the winter making it difficult to assess all features of
it. It lies upstream of the Town of Hayden roughly due north of the Hayden Station. It consists
of two gravel berms constructed to divert and retain water in an old channel of the river which
was cut-off during the high flows of 1984. A gravel berm has been placed in the new main
channel to direct water into the old channel on river left. A second gravel berm is constructed
below the headgate on the left bank to maintain the water level in the old channel and direct flow
toward the headgate. A portion of the lower berm has a low-flow notch constructed in it. It ,
appears that portions of this diversion are re-constructed annually.
The main gravel berm across the new river channel was not examined close-up, but it is '
suspected to completely, though temporarily, block the river. The low-flow notch in the berm in
the old channel appears to be navigable by fish and boats at most river stages. Annual re-
construction activities have resulted in local disturbance of riverine and riparian habitats, although
snow cover prevented a thorough assessment of the extent of this impact. Based on the somewhat
limited information available, it is believed that maintenance of this structure has a moderate
impact on riverine and riparian habitat and that the structure presents a moderate obstacle to fish
passage. '
Shelton Ditch 1
The Shelton Ditch is located roughly three river miles below the Walker Ditch but still
upstream of Hayden and upstream of both occupied and designated critical habitat. The
diversion consists of a temporary instream berm constructed annually of gravel alluvium and
fully blocking the river at the head of a right-hand river bend. The berm is angled slightly
upstream toward the right bank and directs flow to a headgate and ditch on the left bank. The
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