[Awclist] From RRFW FW: Glen Canyon Dam Update April 2013

Sat Apr 20 01:46:21 MDT 2013

>From River Runners for Wilderness
see below for links to their page and wiki link lists as discussed in awc
meeting.

Under Current Operations:  the Grand Canyon river flows for April, May, May
25 steady flow for 1 week, and June are listed 
Thought you might be interested in knowing how much variation in the flows
there are.

>From Celia Southwick

  _____  

From: RRFW Riverwire [mailto:jo at rrfw.ccsend.com] On Behalf Of RRFW Riverwire
Sent: Friday, April 19, 2013 2:25 PM
To: rsouthwick at shamanproducts.com
Subject: Glen Canyon Dam Update April 2013

<http://r20.rs6.net/on.jsp?t=1113127692610.0.1101897124385.327&ts=S0897&o=ht
tp://ui.constantcontact.com/images/p1x1.gif> 

RRFW Riverwire  

Glen Canyon Dam Update April 2013

April 19, 2013

Current Status

The unregulated inflow volume to Lake Powell in March was 362 thousand
acre-feet (kaf) (54% of average). The release volume from Glen Canyon Dam in
March was 601 kaf. The end of March elevation and storage of Lake Powell
were 3599.0 feet (101 feet from full pool) and 11.65 million acre-feet (maf)
(48% of full capacity). The reservoir elevation will continue to decline
until snowmelt and spring runoff begin to fill the reservoir in late spring.

Current Operations

The operating tier for 2013 is the Upper Elevation Balancing Tier, as
establish in August 2012 and pursuant to the Interim Guidelines. The April
24-Month Study projects the end of water year elevation at Lake Powell to be
3,584.13 feet and Lake Mead to be 1,104.18 feet. Since the projected end of
water year elevation at Lake Powell is below the 2013 Equalization Elevation
of 3,646.0 feet and the projected end of water year elevation at Lake Mead
is above elevation 1,075.0 feet, Section 6.B.1 of the Interim Guidelines
provide for an annual release volume of 8.23 maf from Lake Powell during
water year 2013. Reclamation will schedule operations at Glen Canyon Dam to
achieve as practicably as possible an 8.23 maf annual release volume by
September 30, 2013.

Releases from Glen Canyon Dam in April are currently averaging approximately
9,600 cubic feet per second (cfs) with daily fluctuations between
approximately 6,500 cfs at nighttime and approximately 11,500 cfs during the
daytime and consistent with the Glen Canyon Operating Criteria (Federal
Register, Volume 62, No. 41, March 3, 1997). The scheduled release volume
for April 2013 is 550 kaf.

In May, the release volume will likely be about 600 kaf, with fluctuations
for hydropower between approximately 7,000 cfs at nighttime and
approximately 13,000 cfs in the daytime. In addition, to accommodate
airborne data collection, steady releases of approximately 8,000 cfs are
tentatively planned near the end of May, beginning on or about Saturday May
25 and lasting for about one week. In June, the release volume will likely
be about 800 kaf with fluctuations between approximately 9,000 cfs and
17,000 cfs.

In addition to daily scheduled fluctuations for power generation, the
instantaneous releases from Glen Canyon Dam may also fluctuate to provide 40
MW of system regulation. These instantaneous release adjustments stabilize
the electrical generation and transmission system and translate to a range
of about 1,100 cfs above or below the hourly scheduled release rate.
Typically, fluctuations for system regulation are very short lived and
balance out over the hour and do not have noticeable impacts on downstream
river flow conditions.

Releases from Glen Canyon Dam can also fluctuate beyond scheduled
fluctuations for power generation when called upon as a partner that shares
reserve requirements within the electrical generator community (i.e.
balancing area). Reserves provide system reliability in the event of an
unscheduled outage. Glen Canyon Dam typically maintains 43 megawatts (MW) of
reserves (approximately 1,100 cfs). Reserve calls can be maintained for a
maximum of two hours after which time the generation rate should be returned
to the original schedule. If reserves from Glen Canyon Dam are called upon,
releases from the dam can exceed scheduled levels and can have a noticeable
impact on the river downstream from Glen Canyon Dam. Calls for reserves are
fairly infrequent and typically are for less than 43 MW and typically less
than two hours.

Inflow Forecasts and Model Projections

The hydrologic forecast for Lake Powell for the April to July water supply
season projects that the most probable (median) unregulated inflow volume
will be 2.7 maf (38% of average based on the period 1981-2010). The forecast
has continued to decrease throughout the winter and spring season. Based on
the current forecast, the April 24- Month study projects the end of water
year reservoir elevation and storage for Lake Powell will be 3584.1 and
10.30 maf (42% capacity), respectively, which is below the 2013 Equalization
Elevation of 3,646feet. Therefore, consistent with the Interim Guidelines,
the annual release volume from Lake Powell during water year 2013 is
scheduled to be 8.23 maf. Reclamation will schedule operations at Glen
Canyon Dam to achieve as practicably as possible an 8.23 maf annual release
volume by September 30, 2013.

Consistent with the Interim Guidelines, if the August 24-Month study
projects the January 1, 2014, Lake Powell elevation to be less than 3,575.0
feet and at or above 3,525.0 feet and the Lake Mead elevation to be at or
above 1,025.0 feet, the operational tier for Lake Powell in water year 2014
will be the Mid-Elevation Release Tier and the water year release volume
from Lake Powell will be 7.48 maf. This April 2013 24- Month study projects
that, with an 8.23 maf annual release pattern in water year 2014, the
January 1, 2014, Lake Powell elevation would be 3,573.66 feet and the Lake
Mead elevation would be 1,107.60 feet. Therefore, the 2014 Lake Powell
operational tier is currently projected to be the Mid-Elevation Release Tier
with an annual release volume of 7.48 maf.   Based on analysis of a range of
inflow scenarios, the current probability of realizing an inflow volume that
would result in the Mid-Elevation Release Tier and a 7.48 maf annual release
from Lake Powell in 2014 is approximately 65 percent.

Upper Colorado River Basin Hydrology

Since 2005, the Upper Colorado River Basin has experienced significant year
to year hydrologic variability. The unregulated inflow to Lake Powell, which
is a good measure of hydrologic conditions in the Colorado River Basin, has
averaged a water year volume of 10.22 maf (94% of average (period
1981-2010)) during the period from 2005 through 2012. The hydrologic
variability during this period has been from a low water year unregulated
inflow volume of4.91 maf (45% of average) in water year 2012 to a high water
year unregulated inflow volume of15.97 maf (147% of average) in water year
2011. Based on observed inflows and current forecasts, water year 2013
unregulated inflow is expected to be4.53 maf (42% of average), which would
be the second below- average year in a row.

At the beginning of water year 2013, overall reservoir storage in the
Colorado River Basin had increased by approximately 4 maf compared with
water year 2005, which was an improvement over the persistent drought
conditions of 2000 through 2004. Total reservoir storage in the Colorado
River Basin had increased from 29.8 maf (50% of capacity) at the beginning
of 2005 to 33.9 maf (57 % of capacity) at the beginning of 2013. However,
during this period, total Colorado Basin storage experienced year to year
increases and decreases in response to wet and dry hydrology. In addition,
conditions in 2013 have been drier than average and given observed inflows
and current forecasts, the projected end of water year 2013 total reservoir
storage is approximately 29.1 maf (49% of capacity).

This update courtesy of Katrina Grantz, Bureau of Reclamation

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

RIVERWIRE is a free service to the community of river lovers from River
Runners for Wilderness. To join, send an e-mail address to
riverwire at rrfw.org and we'll add it to the RRFW RIVERWIRE e-mail alerts
list. 

Join RRFW's listserver to stay abreast of and participate in the latest
river issues. It's as easy as sending a blank e-mail to
Rafting_Grand_Canyon-subscribe at yahoogroups.com. 

Check out RRFW's Rafting Grand Canyon Wiki for free information on
Do-It-Yourself Grand Canyon rafting info
http://www.rrfw.org/RaftingGrandCanyon/Main_Page
<http://r20.rs6.net/tn.jsp?e=001ZGLFUKNs7CKm37lhThqv248daz8US5AlZHcDA-PdaaJz
R1Zrd1Fz4CiVQU9WXl6xw9exqPLbK0les3vbkD9AFsjcxZ7m_Gr_YlEy-C70NJw-QuDNqvFAjaJV
61vnglK7Q9vLXznv8wHKPqD3plLLRA==> .

See our store offerings and donate at the RRFW
<http://r20.rs6.net/tn.jsp?e=001ZGLFUKNs7CIcaTBVAU_Bd3hfU6rgmbZuzkkVSxmbGeRn
1CTsJBieYl9OX9IWXZvmjPXSozyzGh-8eEl-Vh-txmWfEX4s3n7EsO7RJy-tCYSvDfk42Oi3Fg==
> Store! 

Visit us on Facebook at http://www.facebook.com/RRFW.org
<http://r20.rs6.net/tn.jsp?e=001ZGLFUKNs7CIZCGAy9SuX0Yc3D0QZ4PCHi2KBk_H832Z8
n8rtP4JT7Hwec8s-a8GJ8zbhE9F19GaPicUYebs9kSVXT3KryRwcowNHJ-7Q7nWGunsr6QviLto0
T-asT9Bq> 

RRFW is a non-profit project of Living Rivers.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# # #

Forward email
<http://ui.constantcontact.com/sa/fwtf.jsp?llr=brs4chcab&m=1101897124385&ea=
rsouthwick%40shamanproducts.com&a=1113127692610> 

<http://visitor.constantcontact.com/do?p=un&mse=001sWE8kxl6Jom8n-APlLJ05K5T1
SNUKJjS&t=001RQJDKI4IH2mAbmgDUYqKhg%3D%3D&reason=001IqezpQbqEsU%3D&llr=brs4c
hcab>  	 <http://www.constantcontact.com/index.jsp?cc=TEM_Press_200>  	
This email was sent to rsouthwick at shamanproducts.com by riverwire at rrfw.org |

Update Profile/Email Address
<http://visitor.constantcontact.com/do?p=oo&mse=001sWE8kxl6Jom8n-APlLJ05K5T1
SNUKJjS&t=001RQJDKI4IH2mAbmgDUYqKhg%3D%3D&reason=001IqezpQbqEsU%3D&llr=brs4c
hcab>  | Instant removal with SafeUnsubscribe
<http://visitor.constantcontact.com/do?p=un&mse=001sWE8kxl6Jom8n-APlLJ05K5T1
SNUKJjS&t=001RQJDKI4IH2mAbmgDUYqKhg%3D%3D&reason=001IqezpQbqEsU%3D&llr=brs4c
hcab> T | Privacy
<http://ui.constantcontact.com/roving/CCPrivacyPolicy.jsp> Policy.
River Runners for Wilderness | PO Box 17301 | Boulder | CO | 80308
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.swcp.com/pipermail/awclist/attachments/20130420/55d2893f/attachment-0001.html>