GCDAMP- Questions and Answers Page

UNDER CONSTRUCTION:

• To be added: From Knowledge Assessment_"Assessing what we know and don't know_8-22-2011"- USGS

1. The food web on which fish depend is very simple
2. Availablitity of high-quality food resources limits fish populations- Black Flies and midges are the most important parts of the present food web.
3. The mainstem Colorado River water temperature is typically well velow the termal optimum for native fishes, but recently has been warmer.
4. Warming increases growth/ production of algae and invertebrates.
5. Warming increases the growth rate of humpback chub.
6. We don't understand the decline in RBT between 2001 and 2007.
7. Rainbow and brown trout disproportionately prey on native fish.

WHAT WE DON'T KNOW--

1. Will warmer mainstem temperatures alone allow for increased survival of humpback chub?
2. Do trout have substantial population-level effects on humpback chub?
3. What ages of HBC are most impacted, and by what mechanisms? Competition, predation...

RAFTING RELATED

• Do rafting groups get told not to cave-in sandbars?

SEDIMENT RELATED

• Sediment Retention: How do intervening flows effect retention of sand bars?

FISH RELATED

• How often do native fish get handled?

DAM- General Overview

• What resources have been improved because of the dam?
• Was there more or less vegetation along the river after GC Dam was built?

Monitoring

• How far back does the readings of the gauges go? Pre-dam?

Flow Regimes

• Do steady flows produce more trout?
• Do steady flows lead to increases in vegetation encroachment?