U.S. Department of the Interior

U.S. Geological Survey

Low Summer Steady FloReport Status & PreliminConclusions

Barbara E. Ralston
Background

 U.S. Bureau of Reclamation identified n

of experimental flows (SASF) for native 

 SWCA developed plan beginning in 199

plan in Spring 2000.

-To enhance suryoung native fishstable, warm, pronursery habitats -To increase recfishes -To minimize advnonnative fishes-To contribute to endangered hum
Background

 Inflows indicated an 8.23 MAF year Discussion of implementing SASF- bio

RPA began in January

 Decision to implement in March Reduced planning time Little monitoring in place Revised hydrograph

 Shortened spring Earlier fall HMF Removed Period III
Background

 Request for synthesis document of LS

by AMWG

 Workshops of Principle Investigators a

stakeholders to identify key findings anneeds

 Scatter of P.I.s, limited availability of P

additional analysis, and HFE in 2008 reeffort within GCMRC 

 Draft report through peer review – resp

reviewer comments

 Final approval and posting as USGS O

in January/February
Resources/element studied during 

experiment 

 Physical resources –

 sediment transport/storage Habitat availability Mainstem & shoreline temperatur

 Biological resources –

 Lees Ferry and downstream resp Riparian vegetation

 Cultural resources

 Recreation – campsites, safety, e Economics – power, local econom
Habitat/sediment export

Short-duration high flows (HMF) expothe absence of inputs (Schmidt and oThey can be used to enlarge backwat(Goeking and others, 2003)-Shoreline habitat availability is controlled by geomorphology, but generally increases with discharge (Korman and others, 2004; Protiva 2010)
Mainstem temperatures

Mean mainstem temperatures June – August 2000 f

Mainstem warming is geographically dependent an

volume and release temperatures (Wright and o

Warming was not greater than under MLFF w/simi
LCR Ponding/velocities

227 cms 368 cms 

From Protiva and others, 2010Greater low velocity areas (<2m/s) at 368 
Ponding temperatures

227 cms 368 cms 

From Protiva and others, 2010

Mainstem volumes/temperatures affect LCR and concentrate warm tributary temperature
Shoreline temperatures RM 3

Warming along shorelines occurred though fragmented
Biological Resources

Long-term monitoring approaches in de

2000



1st terrestrial PEP in March 2000

 Aquatic PEP not scheduled until 2001 Monitoring mainstem – trout, carp an

spring/fall mark/recapture initiated in 
Biological Resources

Downstream Fish  Nonnative fish 

abundance in seining samples were similar to previous years (Trammell and others, 2002)

 Increased abundance 

of native fish in seining samples

 More native fish below 

RM 150 in all seining samples
Biological Resources

Downstream Fish  Mean length of fish 

was similar to previous years

 Increases in HBC, 

FMS, BHS lengths associated with tributary contributions

 Reduction in length of 

nonnatives associated with mainstemrecruitment through summer
Biological Resources

Downstream Fish  Trout/brown trout numbers approached t

numbers in 2000 and 2001 in mainstem maffected native fish survivorship (high wpredation)



From AGFD, unpub
Downstream fish

 Native fish did not respond +/- to hydrog

 Tributaries play a large role in native fish repr

Do not know how unsuccessful native fish are recruitment.

 Spring high flows are likely to small in magnit

to be effective- if spawning/larval survivorship 

 May have had increased survival and mainste

Western Grand Canyon by Flannelmouth suck

 Mainstem operations may benefit predat

by increasing water clarity

 Native fish response possibly dependent 

abundances.

 Critical to have robust monitoring in p

evaluate response.
Riparian vegetation

Spring and summer hydrograph proopportunity for tamarisk seedling es

• Spring flows scoured shoreline•June steady flows timed w/tamarisk seed production 
Recreation

Rafting Easier and more campable

area

 Mid-elevation sandbar area 

increase following HMF

 Accidents early but learning 

occurs – boaters adjust

 Perceptions affected by trip 

participants, guides, experience – most passengers/participants perceive experience as excellent
Recreation

Rafting More time spent on water (50 

percent less time at attraction sites (e.g., 3.5 hrs vs. 7 hrs) (Roberts and Bieri, 2001)

 Attraction site selection 

changed slightly beyond the top three sites all trips tend to visit (Deer Creek, Redwall, Havasu

 LCR Pumpkin Spring vs Elves 

Chasm, Nankoweap hike
Recreation

Angling Quality - accessibility, fish s

and quantity

Minimum discharge, fluctuation magnitude, fish 

food availability

Fish abundance, condition of fish siz
Recreation

 Better shoreline access for wading HMFs limited angling Invertebrate biomass – little affected by  Exception - - New Zealand mudsnail bio

increased significantly under steady flow

 May HMF -- may have delayed productio

values by a month compared with previoyears

 September HMF displacing fish was not  Fishery was showing decline prior to 20

difficult to assess angling quality assocwith LSSF
Economics

Limited to financial costs to powecommercial recreation businessescosts. Power customer costs ($32 million) 

 Shifted water allocation & onset of basin- reduced power generation  spot market costs in summer for replacem

market price fixing in 2000 (e.g., Enron) 

 short notice prevented buying supplemen

prior to experiment. 
Economics

Commercial recreation – 124,000 Day rafting not affected White water rafting – $70,000

 equipment damage early in summer Refund evacuated trip

 Angling - $33,000

 Cancel trips during HMF (spring and fall) Holiday weekend HMF in September may 

than if planned in mid-week.

 Total cost include evacuation cost

businesses – health care, lodging, 
Learning Opportunities

 Implementing flows intended to mimic historic cond

systems that are highly constrained by water deliveand the needs of multiple resources is challenging. 

 The magnitude and duration of discharges required 

one resource may be in direct conflict with other res

 Yet, approaching experimentation in a manner that 

impacts to resources can produce a weak experimepoor or undetectable response by the target resourcothers, 2010). 

 The resulting information can be inconclusive for so

costly to others, and can promote the perception thflows are costly, yield little benefit to the target resoto demonstrate the benefits of an environmental flow

 Follow-up cost/benefit evaluations might suggest th

does not merit repeating. Success of an ecosystem further limited when time for planning an experimenmonitoring is reduced, as occurred in 2000.
Learning Opportunities

 Complicated hydrograph reduced learn

opportunities

 Mainstem experiments should focus on 

affected by mainstem operations

- High spring flows run counter to sediment c

goals and have little effect on tributaries, bureworks sediment and creates campable arsummer.

- Habitat stability is key variable – Septembe

this.

- Mainstem spawning is limited by mainstem 

reservoir temperatures a strong driver

 Lack of monitoring weaken interpretive  Publishing results is important step in