Study for Fish Screens at
Existing Delta Facilities
Study for Fish Screens at
Existing Delta Facilities
Dr. Leah OrloffWater Resources Manager
CUWA Board Meeting July 24, 2009
- 2 -July 24, 2009
Study ObjectiveStudy Objective
Analyze the feasibility of pilot fish screens in the Delta for existing export facilities.
- 3 -July 24, 2009
Near-term and long-term benefits– Existing Delta exports are adaptively Existing Delta exports are adaptively
managed based on salvage of delta smelt and managed based on salvage of delta smelt and salmon salmon
– Existing Delta facilities are still necessary Existing Delta facilities are still necessary with any size Isolated Facility, including with any size Isolated Facility, including 15,000 cfs 15,000 cfs
2,000 cfs pilot screens will provide water 2,000 cfs pilot screens will provide water supply reliabilitysupply reliability
The Need for Fish ScreensThe Need for Fish Screens
- 4 -July 24, 2009
Current Operations Current Operations
No screening means no reliability
• In 2009, FWS adaptively restricted exports based on combined delta smelt salvage.
– FWS tightened constraints from mid-May through June because of high salvage levels.
– Despite the restrictions, pumps were shut down for 1-2 days at the end of May to avoid exceeding take limits.
• 2,000 cfs pilot screens would have prevented almost all salvage in spring 2008 and 2009.
- 5 -July 24, 2009
2009: 2,000 cfs screens would have prevented nearly all salvage
2009: 2,000 cfs screens would have prevented nearly all salvage
- 6 -July 24, 2009
2008: Fish screens would have saved up to 186 TAF
2008: Fish screens would have saved up to 186 TAF
Number of days in this month when cumulative salvage exceeded FWS take limit
Acre-feet pumped at Banks this month when cumulative salvage exceeded FWS take limit
If current FWS smelt take limits had been in place in spring 2008, they would have been exceeded in May, June, and July.
Date Take Limit Exceeded
Banks Pumping after Take Limit Exceeded
May 24 22 TAF
June 10 30 TAF
July 1 134 TAF
TOTAL: 186 TAF
- 7 -July 24, 2009
Long- term, fish screens are needed for dual conveyance
Long- term, fish screens are needed for dual conveyance
BDCP modeling shows– Continued reliance on existing Delta exports– Over 50% of supply from existing facilities in drier years
20%
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
AverageExports
(TAF/year)
Wet Above Normal Below Normal Dry Critical
Comparison of Water Supply Diversion Locationfor Different Hydrological Conditions
BDCP Modeling for DRERIP Analysis (1/11/09)
Scenario 1 (mid-level bypass flows)
75%
30%
50%
40%
Ave
rage
Exp
orts
(T
AF
/yea
r)
Wet Above Below Dry Critical Normal Normal
- 8 -July 24, 2009
Pilot Project StudyPilot Project Study
• Project Management:
– Funding partners will enter into an MOU
– Two-tier management: Policy Team and Technical Team
• Schedule: All work to be completed within 6 months of consultant selection.
• Budget: $200,000
- 9 -July 24, 2009
Pilot Project StudyPilot Project Study
Objective: Analyze the feasibility of pilot fish screens in the Delta for existing export facilities. Determine the best:
– location– way to limit predation– way to ensure sweeping velocity– way to move fish out of the South Delta– way to avoid indirect impacts – improvement in water supply reliability
- 10 -July 24, 2009
Scope of WorkScope of Work
Task 1: Review previous studies
Task 2: Develop conceptual alternatives
Task 3: Assess alternatives for feasibility and benefits
Task 4: Perform a blocking analysis
Task 5 Prepare materials for scientific review panel
- 11 -July 24, 2009
Potential Screen LocationsPotential Screen Locations
• Feasibility studies will examine the best placement and design of fish screens to limit predation
• Positive barrier fish screens and tidal barriers provide sweeping velocities for fish survival
North Canal West Canal Italian Slough
ScreenScreenTidal BarriersTidal Barriers
ScreenScreen
Tidal BarriersTidal Barriers
ScreenScreen
Channel ModificationChannel Modification
- 12 -July 24, 2009
Extra SlidesExtra Slides
- 13 -July 24, 2009
2008: 2,000 cfs screens would have prevented nearly all salvage
2008: 2,000 cfs screens would have prevented nearly all salvage
- 14 -July 24, 2009Apr May Jun Jul Aug
0
200
400
600
800
1000
1200
1400
1600
1800
2008
Num
ber
of D
elta
Sm
elt
Delta SmeltWhat if FWS Take Limits were in place in Spring 2008?
0
8
18,343
21
29,970
31
134,067
Take Limit (FWS OCAP BO 2008)Concern Level (FWS OCAP BO 2008)Cumulative Historical Salvage
In the near term, fish screens may ensure water supply reliability
In the near term, fish screens may ensure water supply reliability
Number of days in this month when cumulative salvage exceeded FWS take limit
Acre-feet pumped at Banks this month when cumulative salvage exceeded FWS take limit
If current FWS delta smelt take limits had been in place in spring 2008, take limits would have been exceeded in May, June, and July, costing up to 182 TAF at Banks Pumping Plant.
2008 Data
- 15 -July 24, 2009
Tides provide sweeping velocity in the South Delta
Tides provide sweeping velocity in the South Delta
0 1 2 3 4 5 6 7
100
90
80
70
60
50
40
30
20
10
0
Absolute Value of Sweeping Velocity [ft/s]
Per
cent
Exc
eede
nce
Cummulative Distribution of Sweeping VelocityOld River at Highway 4
1999-2005
JanFebMarAprMayJunJulAugSepOctNovDec
0.4 ft/s
- 16 -July 24, 2009
Screens WorkScreens Work
CCWD’s Old River Intake screen prevents CCWD’s Old River Intake screen prevents fish entrainment fish entrainment – 12 years of operation 12 years of operation
– 982 TAF diverted982 TAF diverted
– Negligible effect on listed fishNegligible effect on listed fish Collected 1 delta smelt (June 2000, 18mm)Collected 1 delta smelt (June 2000, 18mm) Collected 1 longfin smelt (April 2002, 22mm)Collected 1 longfin smelt (April 2002, 22mm) Collected 0 Chinook salmon and 0 steelheadCollected 0 Chinook salmon and 0 steelhead
- 17 -July 24, 2009
Fish Screens May Provide Benefit now and in the future
Fish Screens May Provide Benefit now and in the future
Source: Wim J. Kimmerer, Matthew L. Nobriga. Investigating Particle Transport and Fate in the Sacramento-San Joaquin Delta Using a Particle Tracking Model. San Francisco Estuary and Watershed Science, Vol. 6, Issue 1 (February 2008), Article 4.
• Now: OMR restrictions limit South Delta exports
• Future: Dual conveyance will lower South Delta exports
Fish that are successfully screened from exports have a greater likelihood of escaping the Delta during low export conditions.
- 18 -July 24, 2009
• Drafting a review report – synthesis of previous Drafting a review report – synthesis of previous studies is a first step studies is a first step
• However …However …– DWR report is not examining current conditionsDWR report is not examining current conditions
Outmoded technologyOutmoded technology OMR restrictions have changed Delta hydrodynamics - may OMR restrictions have changed Delta hydrodynamics - may
increase fish screen effectiveness increase fish screen effectiveness Fish screens may prevent SWP from reaching take limitsFish screens may prevent SWP from reaching take limits
– DWR may not have resources to do further studiesDWR may not have resources to do further studies
Current DWR EffortsCurrent DWR Efforts
- 19 -July 24, 2009
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