Upcoming calls
Aquatic Food Base: Ted Kennedy (Team Lead)
- First call: December 18, 2019 from 12:30 – 2:30pm MST
- First call conference line: 844-621-3956;732446632#
- First call Webex: click here
- Second call: January 7 from 1-3pm MST
- Second call conference line: 844-621-3956;738663593#
- Second call Webex: click here
Archaeological and Cultural Resources:
Humpback Chub: Charles Yackulic (Team Lead)
Hydropower and Energy: Craig Ellsworth (Team Lead)
- First call: December 19, 2019 from noon – 2pm MST
- First call conference line: 866-820-4802;4086526#
- First call Webex: click here
- Second call: January 9, 2020 from 1pm – 5pm MST
- Second call conference line: 866-820-4802;4086526#
- Second call Webex: click here
Invasive Fish Species: David Rogowski (Team Lead)
Other Native Fish Species: Brian Healy (Team Lead)
- First call: December 17 at 2:00 PM MST
- First call conference line: 877-991-3746;5981401#
- Second call: December 20 at 10:00 AM MST
- Second call conference line: 877-991-3746;5981401#
Rainbow Trout Fishery: Mike Yard (Team Lead)
Recreational Experience: Lucas Bair (Team Lead)
- First call: December 12 from 2:00 - 3:30 PM MST
- First call conference line: 703-648-4848;686871#
- Second call: January 2 from 10:00 - 11:30 AM MST
- Second call conference line: 703-648-4848;686871#
Sediment: Paul Grams (Team Lead), David Topping (Team Lead)
- First call: December 19, 2019 from 11am MST
- First call conference line: 844-621-3956;730494739#
- First call Webex: click here
- Second call:
- Conference line:
Water Quality: Bridget Deemer (Team Lead), Peggy Roefer (Team Lead)
- First call: December 10 at 3:00 PM MST
- First call conference line: 844-621-3956
- First call Webex: click here
- Second call: December 19 at 1:00 PM MST
- First call conference line: 844-621-3956;730278387#
- First call Webex: click here
Summary [1]
The present Knowledge Assessment seeks to answer three sets of questions for each of the ten selected resource topics, from a scientific perspective:
Status and Trend
- What is our present understanding (hypotheses) concerning the status of the condition(s) addressed by the topic? (Note, quantifiable objectives have not been developed for most resource topics, therefore, a lesson learned from the 2017 Knowledge Assessment was that this question may not be appropriate for all resource topics).
- What is our present understanding (hypotheses) concerning the strength and direction of any trend(s) in these conditions?
- How certain or uncertain is this understanding (confidence)?
Drivers and Constraints
- What is our present understanding (hypotheses) concerning the factors (drivers and constraints – see definitions below) that significantly shape the status and trends in these conditions?
- What is our present understanding (hypotheses) concerning the strength and direction of these effects?
- How certain or uncertain is this understanding (confidence)?
Effects of Management Actions
- What is our present understanding (hypotheses) concerning the ways in which each type of GCDAMP management action affects or could affect the status and trends in these conditions?
- What is our present understanding (hypotheses) concerning the strength and direction of these effects?
- How certain or uncertain is this understanding (confidence)?
The last of these three sets of questions may focus on the following actions, identified in the LTEMP FEIS as components of the Selected Alternative and in other agency decision documents (Note, a lesson learned from the 2017 Knowledge Assessment was that not all management actions need to be evaluated every year.):
- Spring HFEs ≤ 45,000 cfs in March or April
- Proactive Spring HFEs ≤ 45,000 cfs in April, May, or June
- Fall HFEs ≤ 45,000 cfs in October or November
- Fall HFEs > 96‐hr duration
- Trout management flows
- Macroinvertebrate production flows
- Humpback chub translocation
- Mechanical removal of rainbow trout from LCR reach
- Mechanical removal of invasive fish species
- Larval humpback chub head-start program
- Riparian vegetation restoration (not assessed for 2019-20)
- Incentivized harvest (new for 2019-20)
Through its answers to the three core questions presented above, the present Knowledge Assessment seeks to:
- Summarize information on status, trends, and the state of knowledge for the nine priority resource topics, from a scientific perspective.
- Summarize expectations about the likely effects of proposed LTEMP management actions.
- Document the state of knowledge of how antecedent conditions, as well as external drivers and constraints, may affect the outcomes of different management actions.
- Identify potential needs for continuing, increasing, reducing, revising, or adding monitoring, research, and other information-gathering efforts to address potentially crucial gaps in knowledge.
|
Links and Information
|
|
|
Documents
|
|
|
Presentations
|
|
|
Final Knowledge Assessment Summary Tables for Resources Evaluated in 2019-20
|
- Other resources were not evaluated due to time and personnel constraints
|
Recommendations
|
|
Aquatic food base
- Consider testing spring HFEs or other spring-timed flood disturbance to improve food base secondary production. In the absence of a switch in HFE timing, consider studies that disturb macrophytes in spring and/or fall (e.g., by raking or dredging) to understand how HFE timing affects macrophyte response.
- Continue testing Macroinvertebrate production flows for a third consecutive year in 2020 to determine whether these flows improve food base diversity and production. Ensure robust monitoring is in place during next equalization flow.
- Continue drift and sticky trap monitoring at Lees Ferry.
- Continue monitoring of drift downstream, especially adjacent to LCR and at Fall Canyon.
- Consider comparing drift across a range of daily fluctuations, including weekends vs. weekdays.
- Continue monitoring of emergent insects using citizen science.
- Interrogate LF and downstream data for spatial and temporal patterns.
- Consider repatriation of native Colorado River invertebrates to "jump start" colonization.
- Continue monitoring of dissolved oxygen. Consider installing telemetry to allow real-time monitoring of dissolved oxygen levels to enable more rapid response when low levels occur.
- Continue monitoring nutrients downstream.
Hydropower
- Look for ways of increasing reservoir elevation at Lake Powell.
- Reduce bypass for HFEs by identifying the minimum duration needed to rebuild sandbars that meet the LTEMP goals for sediment-related resources.
- Move forward on cost/benefit analysis on adding generation on the bypass tubes.
- Allow flexibility as described in the ROD to adjust monthly volumes to increase energy value and capacity and reduce net firming purchases.
- Avoid moving water from higher value months to lower value months.
- Look for ways to conduct experiments like Bugflows and TMFs that can be done coincident with power production.
- Avoid experimentation that could interfere with power production in July and August (particularly the testing of Low Summer Flows (LSF), possibly testing of TMFs).
- Conduct an experiment that increases the daily fluctuation factor to 12 in Dec, Jan, Feb and/or an experiment that raises the daily fluctuation cap to 10k cfs/day. Monitor effects on Recreation and Sediment.
- Evaluate the scalibility of fluctuations to release volumes to see if the effects of fluctuations greater the 8k cfs during higher release volumes could be acceptable to Recreation.
- LTEMP placed an 8k cap based on a misinterpretation of the 1987 Bishop Study which actually stated that a “10,000 cfs threshold was determined to be the point at which fluctuations begin to be perceptible to recreationists.” We would recommend correcting that misinterpretation when referring to the Bishop Study in the future.
- Design TMFs to further test impacts of increased fluctuations to hydropower production, recreation, and sediment (making sure focus of experiment remains on trout management). Conduct a recreation survey of impacts of increased fluctuations during TMF study.
- Keep the analysis updated past LTEMP.
- Evaluate how increased wind and solar coming into the grid is affected by current ramp rate restrictions.
- Keep experimentation bookable as non-reimbursable.
- Advocate for responsible experimentation as it still impacts the Basin Fund.
Other native fish
- Continue monitoring program to understand trends, and reconvene expert panel to consider augmentation plan details. Long-term mark-recapture data provide valuable insights into population dynamics of tributary populations. Some tribs have been monitored for short periods of time.
- Reintroduce BHS to SHI after removal of remaining rainbow trout. Reclamation of the SHI watershed to 100% native fishes would provide an ideal opportunity to study population dynamics of native fish in the absence of invasive species.
- Continue monitoring effects of invasive trout on bluehead sucker populations in the Colorado River particularly at low trout abundance. Consider mark-recapture analysis to assess population trends beyond 2010 (cf Walters et al. 2012) and related to trout population dynamics.
- Continue larval fish monitoring program, sample trib mouths during spawning to determine overlap of RBS and FMS
- Consider extending weekend stable flows and measure thermal response in backwater habitats, and continue monthly monitoring April-September.
- Monitor response of native fish larval production and recruitment to annual thermal regime. Monitor for invasions of warmwater nonnative fishes near dam and lower river, as well as Kanab, LCR (potential trib sources).
- Develop study plan for assessment of importance of sediment dynamics and backwater habitats to native fishes in w. Grand Canyon.
- Develop plan for augmentation of razorback sucker, and consider developing plan for reintroduction of Colorado pikeminnow. If high steady equalization flows occur, monitor movements of native and invasive fishes between Havasu and Col. River, and between Lake Mead and Colorado River, past Pearce Ferry rapid.
- Continue to try to relate food base fluctuations with native fish population dynamics. Explore relationship of food base to low razorback sucker larval survival in western grand canyon.
- Review invasive fish surveillance program and make changes, where necessary. Continue existing monitoring, including nonnative hotspots (Slough, LCR, Kanab, etc.), and mainstem larval/small-bodied (to detect reproduction) and electrofishing. Consider evaluating potential outside sources in the LCR or Kanab drainage. Assess potential for Pearce as a barrier, and determine passage through GC Dam.
- Test spring HFE. Consider experimental design to combine with a TMF to further limit brown trout recruitment.
- Consider developing study plan to address lack of information relating experimental flows to razorback. This is a conservation measure in LTEMP BO. Continue NPS biologists working with BOR and contractors.
- If mechanical removal triggered, devote resources to monitoring impact on native sucker populations. Change title of this action to Mechanical Removal of Nonnative trout from LCR reach (removing brown trout too).
- Initiate incentive harvest of brown trout as soon as possible, along with rigorously designed monitoring program to assess changes in vital rates of brown trout, and relationships of vital rates with harvest, and other environmental factors.
Recreational experience
- Keep mean daily flows at a minimum of 12k cfs. Minimize flow ranges greater than 5k cfs during operational and experimental flows while meeting downstream resource objectives. Increase experimental flow education and outreach to anglers. Minimize duration and magnitude of experimental flows that create access issues while still accomplishing downstream resource objectives.
- Consider 8 kcfs as the minimum flow, and slowing down ramp rates as much as reasonable during TMFs. Consider research to further refine whitewater preferences for flow fluctuation.
- Operate Glen Canyon Dam in such a manner to manage rainbow trout recruitment and promote and foodbase to meet rainbow trout specific condition and abundance measures while addressing other downstream resources. Implement measures to identify rainbow trout catch greater than 16 inches.
- Consider phosphate inputs to boost macroinvertebrate production.
- Minimize daily fluctuations, especially at lower water releases.
- Consider minimum flows/fluctuations at 6,000-9,000 cfs.
- Conduct a cost benefit analysis on effects to hydropower to operate dam without daily fluctuations.
- Design management actions (e.g., flow magnitude and duration during Bugflows) to minimize impacts to usable campsite area.
- Conduct HFEs whenever conditions are appropriate. Whitewater boaters recognize the positive beach building effects even with the inconvenience of very high flows.
- Although HFE's build sandbars, they do not scour vegetation, which continues to expand into campsites. Develop plan for vegetation management that targets sites where re-establishment is least likely and monitor results.
- Campsite monitoring is needed. If campsite areas continue to decline, consider actions in addition to high flows if larger campsites are required. Short-duration high flows are effective for increasing campsite area.
- Design operational flows and management actions to minimize impacts to and manage for foodbase and rainbow trout recruitment while addressing downstream resource objectives.
- Weekend water flows, holiday flows, MPF should be equivalent to mean daily flow for a given month.
- When possible, consider spreading equalization flows evenly throughout water year to minimize negative impacts of equalization flows on sandbars.
Water quality
- Work to improve our understanding of low dissolved oxygen interflows and experiment with aeration options directly below the dam.
- Developing models to better understand how changes in Lake Powell elevation will influence temperature and nutrients
- Work should continue towards peer reviewed literature that describes the link between GCD outflow phosphorus concentrations and riverine productivity.
- Samples for nutrients should continue to be collected monthly above and below GCD.
- Examine the potential for HFEs to affect fish immediately below GCD (i.e. gas bubble trauma).
|
Final Knowledge Assessment Tables for Individual Resources
|
|
|
|
