Willwood Dam and Shoshone River February 2018 Update

Wyoming Department of Environmental Quality  | view as a webpage

Wyoming Department of Environmental Quality

Willwood Dam and Shoshone River Update

Presentations from November 28, 2017 Public
Thank you to everyone who attended the November 28, 2017
public meeting in Cody. Updates were provided on the: Wyoming Department of
Environmental Quality’s (WDEQ) water quality monitoring efforts; Wyoming Game
and Fish Department’s fish sampling results; draft operating recommendations for
Willwood Dam; and data collection efforts upstream and downstream of the dam by
the United States Geological Survey (USGS). We have posted the presentations
from that meeting in the “Program Resources” at the bottom of the
Willwood Dam
and Shoshone River

Operating Recommendations: The public comment period for the Willwood
Dam Operating Recommendations
closed on December 22, 2017. WDEQ is
currently reviewing the comments received and will work with cooperating
agencies to develop responses. WDEQ will then make any necessary changes to the
recommendations. WDEQ plans to make additional updates to the recommendations
as new data and information become available.

Winter and Springs Flows in the
Shoshone River: 
Following unusually high fall inflows to Buffalo Bill Reservoir that required corresponding high fall releases, in December, the United States Bureau of Reclamation (USBR) announced that they would be releasing higher than normal flows
in the Shoshone River below Buffalo Bill Dam during the winter. On December 20, 2017, USBR adjusted reservoir releases to provide approximately 560 cfs at the Shoshone River gage near Cody, which is about
150 cfs above normal. Based on the most recent, February 1 forecast, projected
April through July inflows to Buffalo Bill are 142% of average and necessitate
even greater releases to prepare for runoff. As a
result, flows out of Buffalo Bill were increased to approximately 810 cfs this week. USBR expects to maintain
this flow until the end of February. USBR will continue to coordinate with the
Willwood Irrigation District and other cooperating agencies as they plan for
additional changes to flows this spring. 

Bathymetric Survey of Sediment Behind
Willwood Dam: 
In late November 2017, WDEQ and WGFD completed a bathymetric
of the sediment behind Willwood Dam. This information will be used
to help quantify changes in the amount of sediment behind the dam as various
management activities are implemented. A second survey is expected to occur in
2018 following peak flows on the Shoshone River. Estimates of the volume of sediment
behind the dam can be used to help determine how to best manage the deposited
sediment while also protecting the downstream fishery.

Turbidity and Suspended Sediment Data
Collection Efforts Above and Below Willwood Dam: 
Last year, WDEQ contracted with the United States Geological
Survey (USGS) to install turbidity sensors and other equipment on the Shoshone
River upstream (06283995) and downstream (06284010) of Willwood Dam to determine
the timing and quantity of suspended sediment coming into and exiting the dam (
Scope of Work
). The turbidity sensors were operational from approximately
mid-October to late December, but had to be taken down due to issues with
powering the equipment during the winter months. In December, USGS installed a
hydroacoustic device at the downstream site that will be used in conjunction with
the turbidity sensor, manually collected flow, and suspended sediment
concentration data to develop a relationship that will provide real-time
suspended sediment concentrations upstream and downstream of Willwood Dam. See
2018 update
for additional information. In the coming months, USGS will be working
on getting the turbidity sensors online again and installing a hydroacoustic
device at the upstream site. This information will be used to help more
effectively manage sediment at the dam and minimize potential impacts to the downstream

Shoshone River Water Quality Monitoring: WDEQ continues to monitor the water quality of the Shoshone
River from Cody to Lovell. Water quality samples are collected at 9 sites every month. In
addition, invertebrates and algae were sampled this fall at the reaches that
could be safely sampled given the higher than normal flows. WDEQ plans to
continue the monthly water quality sampling through 2018 and will collect
another round of biological (algae and invertebrates) samples in the fall of
2018. WDEQ’s
sampling and analysis plan for this
effort is available on the Willwood Dam and Shoshone River Project page.

Willwood Work Group 3 Update: Work Group #3 has been meeting
regularly over the past eight months to address potential sediment sources into
the Shoshone River and its tributaries upstream of Willwood Dam. Most
importantly, Work Group #3 is working to identify potential sediment reduction
projects and connect landowners, agencies, and organizations interested in
voluntarily implementing such projects with technical and financial resources.
The work group is discussing monitoring activities that would help the group
achieve its objectives, with some preliminary sediment samples collected by
WGFD on two tributaries in 2017. The group is also discussing public outreach
activities that will help support sediment reduction efforts in the watershed.
A second field tour is tentatively being planned for June 2018 as part of
outreach activities. The work group has also started to draft a watershed plan
that will summarize the findings and recommendations of the work group. If you
are interested in participating on Work Group #3, please contact the Powell
Clarks Fork Conservation District at 307-754-9301 or Jennifer Zygmunt, WDEQ, at
307-777-6080 for more information about future meetings.