Linkages between Lake Pow

Reservoir and the Colorad

River Below Glen Canyon Da

Mark Anderson and Ken Hyde

Glen Canyon National Recreation Area

Division of Science and Resource Management
Grand Canyon Protection Act

The Secretary shall operate Glen Canyon D

accordance with the additional criteria and 

plans specified in section 1804 and exercise 

authorities under existing law in such a ma

protect, mitigate adverse impacts to, and i

the values for which Grand Canyon Nationa

and Glen Canyon National Recreation Area 

established, including, but not limited to na

cultural resources and visitor use.

Photo BOR
Glen Canyon National Recreation Area 

• GLCA is larger than Grand Canyon NP

(Grand Canyon = 1.22 million acres / Glen Canyon = 1.25 million acres)

• GLCA extends north as far as Canyonlands NP

• Longest average stay of any NPS unit (4.5 days)

• “Recreation Areas” follow the same

management as any NPS unit

• Lake Powell = 90% of visitors, 13% of GLCA
What is the largest man‐mad

reservoir in the United States

Measure Mead Powe

Surface Area (acres when full) 158,000 163,0

Main Stem Length (miles) 110 186Shoreline Length (miles) 550 2000
Limnological Monitoring
04 Oct – 21 Nov 2005 14 Oct – 22 A

  

Limnological Monitoring
Limnological Monitoring

• Uncertain Future

• Contract End ‐‐‐‐ BOR GCMRC• Uniflight Sank

• Bill Vernieu Retired

• Currently Patched

• NPS staff and Vessel 321• GCMRC doing monthly forebay monitoring

• BOR doing quarterly lake‐wide monitoring

• UT USGS contract?• AMWG Needs?
Linkages – DISSOLVED OXYGEN

• Drawing from mid‐column, GCD can pass

water from which oxygen has been depleted

• Low oxygen levels can kill aquatic organisms,

especially trout

• Low oxygen that can pass through the dam is created at the infl

• Organic matter resuspended from the bottom and coming in with the r

up the oxygen

• Low oxygen water cannot get oxygen if travelling deep

• These flows can be detected months before they reach the dam

• Steps can be taken to mitigate the effects on the river

• Aeration (in forebay or at turbines), Cavitation, other?
• Dams are imperfect barriers to downstream fish moveme

Linkages ‐ FISH

• Many species that could be problematic exist above the d

• Green Sunfish – Lake Powell likely source for slough population• Smallmouth Bass – potentially more detrimental than Green Su

• Walleye and Northern Pike are currently concerns above the lak

• Fish populations of Lake Powell are fairly well understood 

but the specific information needed to address issues in t

not included

• What fish use the dam area?

• What fish survival occurs through the dam?

• How do HFE’s effect fish passage through the dam?

• What is the fate of surviving fish?
• Water Clarity

• Phytoplankton/Zooplankton• Fishery• Waterfowl• Aquatic Vegetation• Harmful Algal Blooms

• Dissolved Oxygen• Dreissena polymorpha

Quagga Mussel Effects Monitoring
• Generally trapped by the lake, mostly near inflows

• Deep Sediment Deltas – Colorado >180ft, SJ >120ft, Esc >80ft

Linkages – SEDIMENT• Big issue that will only get bigger

• Hite• San Juan Marina• Waterfalls

• Long distance transport in density currents

• 10cm/year sedimentation at dam

• Contaminants ‐ Locked up or released based on flows

• Oxygen demand

• Turbidity (WW creek)
Linkages – MERCURY

Lake Powell Striped BassConsumption Advisory (UT and AZ)(from Dangling Rope Marina south to the dam)

• Children should limit their consumption of

Striped Bass to one 4‐ounce meal per

month.

• Women of childbearing age should limit

their consumption of Striped Bass to two 8‐

ounce meals per month.

• Adult women past childbearing age and

men older than 16 should limit their

consumption of Striped Bass to eight, 8‐

ounce meals per month.
Linkages – MERCURY
Other Existing or Potential Issues

• Plankton

• Energy & Food Web changes• AIS (quagga & other AIS effects)

• Nutrients• Dissolved Organic Carbon• WEEDS – Exposed Shoreline• Archaeology• Water Levels

• HFE = 4ft to 6ft drop in lake level• Lake fish habitat

• Upper basin native fish

• Waterfall barriers• Inflow condition

• Habitat• Contaminants
Future

• The phrase “Colorado River Ecosystem” would appropriat

the river from mountains to the ocean, but usually we don

mean the full area addressed by the GCPA

• GCPA Parks are GLCA and GRCA – no hierarchy is establish

• GLCA issues are more esoteric, especially when making a 

between dam existence and dam operation

• Perspective can be everything – Understanding of the rive

poor without looking at the source; holistically considerin

and the river may provide management opportunities bey

current approach
Thank you!

Mark AndersonAquatic EcologistGlen Canyon National Recreation Area928‐608‐6266mark_anderson@nps.gov