WSPC12502 ‎(2)‎

• File Number: 8220.101.10
• Description: Colorado River Water Projects - Glen Canyon Dam-Lake Powell - Adaptive Management
• State: CO
• Basin: Colorado Mainstem
• Date: 6/10/1998
• Author: Unknown
• Title: Glen Canyon Dam Management Objectives - Draft - 06-10-98
• Water Supply Pro - Doc Type: Report/Study

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IN 2.2 Evaluate feasibility of short term or long term changes of water temperature
through selective withdrawal.

SEDIMENT RESOURCES

Goal: To maintain a range of sediment deposits over the long-term, including an
annually flooded bare-sediment (unvegetated) active zone, a less frequently flooded vegetated
zone, terraces (within the 45,000 cfs river stage), and backwater channels. Managing sediment
resources will be on a reach-scale basis. Should significant and localized adverse impacts occur,
site-specific mitigation would be considered.

Definition: Sediment resources include a broad array of material, ranging from
suspended fines to coarse gravels. Primary interest relates to both material in suspension, which
affects benthic capability, as well as stored sediment in beaches and channel margins, which
affects recreation.

MANAGEMENT OBJECTIVES. STAKEHOLDER INFORMA nON NEEDS. MANAGEMENT ACTIONS

MO 1: Maintain a long-term balance of river-stored sand to support maintenance flow (in years
of low reservoir storage), beach/habitat-building flow (in years of high reservoir storage), and
unscheduled flood flows. Maintain system dynamics and disturbance by annually (in years which
Lake Powell water storage is low) redistributing sand stored in the river channel and eddies to
areas inundated by river flows between 20,000 cfs and maximum power plant capacity.

IN 1.1 Define historical and current (character and structure) levels of river stored
sediment in system and associated flow regimes

IN 1.2 Define minimal levels of river stored sediments necessary to maintain long term
sandbar, backwater, instream sediment deposits

IN 1.3 Develop procedures to monitor and predict impacts of alternative operating
criteria (flow regimes) on river stored sediment, and impacts in select reaches

IN 104 Measure and model sediment contributions from all contributing sources,
including tributary and high terrace sources

IN 1.5 Evaluate the geology/geomorphology within Glen Canyon to: (1) determine
historical changes in size and extent of beaches, sandbars and backwaters, (2)
quantify sediment (size class and quantity) input from side channels, (3)

Revised 6-10-98