Warmer Water?
Gcrg has submitted this letter
to the Bureau of Reclamation (bor) in response to a request for comments
to be considered in the development of an Environmental Assessment (ea)
regarding the feasibility of installing Temperature Control Devices (tcd)
on two penstocks at Glen Canyon Dam. The Bureau had released a Draft ea
on an eight-unit tcd for Glen Canyon Dam in 1999, but did not finalize
that assessment and National Environmental Protection Agency (nepa) process
due to questions about the potential adverse impacts of the device on
downstream resources. In simple language the initial ea did not adequately
address serious concerns, they’ve been studying the potential for
a tcd in the interim, and they’re ready for Round Two. If you would
like to receive a copy of the Draft ea when it is available, please contact
the US. Bureau of Reclamation, attention Nancy Coulam, UC-720, 125 South
State Street, Room 6103, Salt Lake City, ut 84138-1102, or by email to
ea_comments@uc.usbr.gov
April 29, 2004
Bureau of Reclamation
Attn: Nancy Coulam, UC-720
125 South State Street
Room 6103
Salt Lake City, Utah 84138-1102
Re: Glen Canyon Dam Temperature Control Device, Comments
From: Grand Canyon River Guides
Dear Ms. Coulam,
Following are comments from Grand Canyon River Guides (gcrg) on Reclamation’s
plans to develop an Environmental Assessment regarding the feasibility
of installing temperature control devices (tcd) on two of Glen Canyon
Dam’s penstocks.
1) Potential environmental effects of construction and operation of a
two-unit pilot project tcd:
a) The tcd could reduce a full (45,000 cfs) sediment conservation flow
experiment following a sediment trigger during construction. Tcd construction
might even further reduce the flow if it is concurrent with scheduled
generator/turbine maintenance.
b) Warmer water temperatures may support elevated levels of water-borne
pathogens and adversely affect human health in the downstream reach.
c) Warmer water may distinctly advantage predator, competitor and parasite
species to native fish. Warmer conditions in the Little Colorado River
(lcr) have apparently advantaged a parasite that is detrimental to the
humpback chub (fish in the colder main-stem have a lower infection rate
than the fish in the warmer lcr.)
d) Warmer water/water quality from the near surface may introduce waterborne
disease or pathogens that may be detrimental to human use of the downstream
reach.
e) Warmer water/water quality
from the near surface may introduce diseases or competitors, predators
or parasites that could adversely affect native fish populations. It may
also introduce other key biological and physical water quality factors
from the lake’s upper water levels.
2) Reasonable alternatives to the proposal:
a) Compare native fish recruitment and survival in the upper basin due
to the affects of the Flaming Gorge tcd with what could be expected in
Grand Canyon.
b) Use the tcd at Flaming Gorge to carry out temperature variation experiments
on native fish populations in the upper basin. The results could be used
for extrapolation of tcd effects in Grand Canyon.
c) Ensure that refitting two intakes is sufficient to achieve the desired
goals and carefully consider what number of modified intakes will accomplish
an adequate test in a reasonable time period under different Water Year
scenarios (High, Medium, and Low).
d) Use the predicted warmer temperatures in the near-term from Lake Powell
(due to reservoir draw-down) as a stand-in for some of the experiments
at a much lower cost.
3) Measures to avoid or lessen environmental impact:
a) Ensure scheduling of tcd construction and generator/turbine maintenance
that will not inhibit the implementation of any future Beach Habitat Building
Flows.
b) Monitor and research the causes of outbreaks in waterborne pathogens
to determine if temperature is a controlling factor for human health.
c) Use information from other agencies to determine water quality related
disease outbreaks on the Colorado River below Glen Canyon Dam. You can
contact: Coconino County Health Dept., attn: Marlene Gaither (928) 226-2769.
d) Incorporate strong biological data supporting conclusions and specific,
well designed monitoring studies that can discern any detrimental impacts
to native fish in this complex system.
e) Examine closely the risk factors for the introduction/advantaging of
disease, parasites, competitors and predators that could adversely affect
native fish. Examine research on native fish populations in Cataract Canyon
for any parallels.
f) Use existing knowledge and research from the upper basin conditions
to inform the decision on whether to build a tcd on Glen Canyon Dam. We
should understand the principal factors in native fish decline before
moving forward with construction of the tcd.
Thank you for the opportunity to comment.
Sincerely yours,
John O’Brien, President
Andre Potochnik, amwg Representative
Matt Kaplinski, twg Representative
Lynn Hamilton, Executive Director
