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Snake/Salt River Basin Advisory Group
July 09, 2003
Facilitator Sherri Gregory welcomed the group and the meeting
was called to order at 6:04p.m. All attendees introduced themselves,
followed by a review of the overall meeting agenda. A sign-in sheet was
passed around to record attendance. The next meeting is scheduled for
November 5th in Afton.
Water Development Commission Report
Barry Lawrence updated the BAG on the status of the plans for the other
basins. The BAGs for the Wind/Bighorn, Powder/Tongue and Northeast
Wyoming Basins will be meeting on July 15th in Thermopolis, July 16th
in Kaycee, and July 17th in Lusk. The Platte Open house meetings were
held on June 2nd in Saratoga, June 3rd in Douglas, and June 4th in Pine
Bluffs. The Platte BAG formation is scheduled for September 4th in
then discussed the status of all basin studies and agendas for future
meetings. He concluded his remarks by introducing Debra Cook with the
Water Resources Data System. Debra was recently hired to fill a vacancy
with the water planning team.
Water Resources Data System
Debra Cook announced that irrigation surveys had been mailed the prior
week. If an entity has received one in the past, and has not yet
received the current one, pleast contact her.
Canal Modernization/North Canal Project (2596kb PDF)
Stephen also discussed the Dolores Project, a Bureau of Reclamation
project equipped with SCADA facilities. Every agricultural user on the
system has pressurized water on demand; with open valve center pivot
starts. The SCADA system recognizes flow increases and 8 checks are
operated 24 hours per day. An operator can see the condition of every
gate in the system from one vantage point.
Stephen Smith of Aqua Engineering, Inc. discussed canal
modernization techniques. It was noted that the automation of flow
measurements with supervisory control and data acquisition (SCADA)
facilities has several advantages. Collected data is posted to a
website, with readings every few seconds instead of being manually read
twice per day, thus increasing the accuracy of the data and decreasing
the manual effort involved. The cost of SCADA has decreased
dramatically, from approximately $10,000.00 per flume to about
$5,000.00 per flume.
Dual Systems were also discussed, in which the ditch company would be
the raw water purveyor. Residential users would be provided with
pressured raw water for the purpose of watering or non-potable
use. Examples of such projects in both Utah and Colorado were
discussed. In such systems users would need two water valves, one
for potable and one for non-potable water. Costs for this kind of
project would be regional and ditch company specific. Additional
infrastructure costs would probably be in the range of $2000.00 to
$3000.00 per residential lot, but this cost could be done on a 30-35
year payback. Advantages of dual systems are a decrease of water
processing facility use and lower cost to end users for non-potable
water, typically ½ the cost of potable water.
Amy Johnson of Aqua Engineering, Inc. discussed the North Canal –
Grover Level I rehabilitation study being undertaken in the
basin. Aqua is currently working on seepage loss analyses,
developing an inventory on all structures, and putting together
recommendations for improvements with conceptual designs and cost
estimates. This study will be finished in October. A brief
question and answer session followed Amy’s presentation.
Lesa Stark of the Bureau of Reclamation discussed the Water 2025
initiative, which provides a basis for a public discussion in advance
of water crises and sets forth a framework to focus on meeting water
supply challenges in the future. This framework includes six principles
to guide the Interior in addressing water problems, five realities that
drive water crises and four key tools to help proactively manage scarce
water resources. The six principles are: operate under current laws,
enhance water use, enhance water conservation, improve water treatment
technology, use collaborative approaches to minimize conflicts, and
utilize existing infrastructure. The five realities are: water
shortage, population increase, over-allocated water systems, aging
infrastructures, and crisis management. The four four key tools are:
conservation efficiencies, collaboration, improvement of technology,
removal institutional barriers.
The kick-off meeting for Water 2025 was
held in Colorado in May of 2003. This initiative has 11 million in
funding for actual projects in 2004. The money will be focused on
hotspots, places with high growth and drought. The Bureau is currently
working with Ron Vore, WWDC Conservationist on any Wyoming
Seismicity and Associated
Hazards in Teton and Northern Lincoln
Counties (584kb PDF)
James Case of the Wyoming State Geological Survey discussed
earthquakes and associated geologic hazards. Earthquakes in Wyoming
occur because of movements on faults, movements of the magma chamber
beneath Yellowstone, or from man-made events such as a mine collapse.
Wyoming has been classified by the Federal Emergency Management Agency
as having a very high seismic hazard. Historically, there have been
in every county in Wyoming, with most earthquake activity
being centered in Teton
County (515kb PDF),
Northern Lincoln County (852kb PDF), and
Yellowstone National Park.
Historically, fault-related earthquakes in Wyoming have been tied to
deeply buried faults that are not exposed at the surface. Buried faults
with no surface exposure generally create earthquakes with magnitudes
of 6.5 and less. There are a number of actives faults that are exposed
at the surface in Wyoming. Those faults are capable of generating
earthquakes up to magnitude 7.5. Many of the exposed active faults in
Wyoming are considered to be overdue for activation. They activate
every few thousand years on average.
There are a few exposed active faults that are capable of generating
magnitude 7.0-7.5 earthquakes in Teton and northern Lincoln counties.
The Teton Range exists because of recurrent movement along the Teton
fault, which lies at the base of the Tetons. The Star Valley in Lincoln
County is present because of recurrent movement along the Star Valley
fault. The maximum earthquake expected from the Teton or Star Valley
faults would have a magnitude of 7.5, releasing as much energy produced
by a one megaton h-bomb. In other areas of Teton and Lincoln Counties,
earthquakes as large as magnitude 6.5 could occur. Magnitude 6.5
earthquake release as much energy as a Hiroshima-type atomic bomb.
Teton fault is expected to generate a magnitude 7.5 earthquake every
800-3,600 years. It last activated between 4,800-7,000 years ago, and
as such is considered by many to be overdue for activation. The worst
case scenario for Jackson would be a magnitude 7.5, intensity X
earthquake during a wet period (magnitudes are a measure of the energy
released and intensities are a measure of ground shaking). Landslides
could result from such an earthquake, and there would be the
possibility that landslide dams would form in some streams and rivers.
In addition, ground shaking would be severe across most of the county.
Recent studies indicate that some soils near Jackson Lake would amplify
the effects of ground shaking, and the shaking would actually be
similar to that experienced in a magnitude 8.0 to 9.0 earthquake. The
intensity of shaking in Jackson would be VIII, with the possibility of
intensity IX in Teton Village and intensity X at Jackson Lake.
Intensity VIII earthquakes can result in considerable damage in
ordinary buildings and great damage in poorly built structures.
Intensity IX earthquakes can cause considerable damage in specially
designed structures and great damage and partial collapse in
substantial buildings. Well-designed frame structures could be thrown
out of plumb.
Along the Star Valley fault magnitude 7.5 earthquakes
generally occur every 2500 to 6000 years, and it’s been 5600 years
since such an event has occurred. Intensity IX shaking could occur
along the east side of the Star Valley, and Intensity VIII shaking
could occur along the west side of the valley. The Star Valley fault
crosses through the town of Afton.
Building codes are important in areas with such significant
potential. Jackson and Teton County have adopted current building
codes, including the seismic provisions. No building codes have been
adopted in northern Lincoln County. When building in an area like
northern Lincoln County, it is advisable to design and build structures
using the building code for guidance, even if it has not been adopted.
If a structure is to be built near an exposed active fault, it is
advisable to over-build the structure. It is also important to
determine the locations of landslides before building in the area. A
geologic assessment is always a good idea. Landslide areas can be
stabilized by building retaining walls and establishing good subsurface
and surface drainage. Areas near irrigation or irrigation canals are
sometimes prone to landslides.
Jim discussed the fact that no seismic network currently exists in
area to accurately monitor earthquake activity. At the current time,
earthquakes can only be pinpointed to a region within 3-5 miles of the
epicenter. The USGS, in coordination with the University of Wyoming,
the Jackson Hole Geologists, the WSGS, and the University of Utah will
set-up a new network over the next year, pending federal funding. The
USGS had already established one new seismic station in the Red Top
Meadows area, but another 10-12 are needed. Discussion followed.
Jackson Lake Power Development Study
This presentation will be scheduled for a later meeting.
Kirk Heaton,Western Wyoming Resource Conservation and Development Area
Council, announced that a grant writing workshop would be held November
17-20, 2003 in Jackson.
The meeting adjourned at 8:30 p.m.