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Upper Truckee River Restoration
Lake Tahoe, California
Presented by Brendan Belby – Sacramento, California
Mike Rudd (Project Manager), Charley Miller & Chad Krofta
Declines in Tahoe’s Water Clarity
Source: Tahoe Resource Conservation District, 2003
The Upper Truckee River watershed viewed from its headwaters near Carson Pass north towards Lake Tahoe
• Comstock Era Logging & Mining
• Grazing
• Urbanization
• Channelization
• Floodplain Encroachment
Historic Land Uses
Source: USDA, Lake Tahoe Watershed Assessment, 2000
Historic Large-
Scale Logging
• 60% of Tahoe Basin
was clear-cut
• 95% is second growth
forest
Source: Photo by Dr. Robert Orr, property of California Tahoe Conservancy
Upper Truckee Marsh in 1930
Tahoe Keys
Upper Truckee River
Trout Creek
Upper Truckee Marsh Today
# homes
increased 500-
19,000 from
1960-1980
Source: Steve Winter, M.S. Thesis, U.C. Davis, 2003
Sediment Accretion Rates
•Logging: +600%
•Urbanization: +350%
Planform Adjustments to Sediment Supply
1940 2003
Sedimentation in response to logging?
Minimal planform change reflection of low energy &
cohesive meadow soils
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
01/01/71 12/31/73 12/30/76 12/30/79 12/29/82 12/28/85 12/27/88 12/27/91 12/26/94 12/25/97 12/24/00
Date of Measurement
Ele
va
tio
n (
ft a
bo
ve
fix
ed
da
tum
)
0
500
1000
1500
2000
2500
3000
3500
Me
an
Da
ily F
low
(cfs
)
pzf
Mean Daily Flow
Profile Adjustments to Sediment Supply
Bed elevation changes in response to urbanization?
Channel Response
Downcutting
•Doubling of channel capacity
•Lacustrine layer exposure
Channel Response
Bank Erosion
•Sod blocks
•Fine-grained sediment input
Channel Response
Aggradation/Widening
Incipient Floodplain
•New depositional landforms
•Lower base level
•Slow development
Taken 5/5/04 at ~350 cfs, RS 16000
Existing Condition:
•Slope: 0.001
•D50: 4 mm
•Width: 65 ft
•Depth: 5-6 ft
•Capacity: 700 cfs (2-yr RI) to1,300 cfs (5-yr RI)
American Forests 1935
“Crooked streams are
a menace to life… Du
Pont Dynamite has
straightened many
thousands of miles of
crooked streams…Du
Pont has an explosive
for every purpose”
Reaches 3 & 4 – Airport Reach
Clients: City of South Lake Tahoe and
California Tahoe Conservancy
May 17, 2005 Flood
Upper Truckee River – Reaches 3 & 4
Reaches 3 & 4
New Channel
Construction
Started in
Summer 2008
Source: City of South Lake Tahoe
•Reduce channel capacity to increase overbanking•Increase deposition & storage of fine suspended sediment•Decrease bank erosion•Raise groundwater levels•Improve habitat
Major Project Goals
Alternative 1 – Existing Channel with Habitat Improvements
1.Construct in-channel habitat structures and bank stabilization features
2.Locally narrow channel at locations with large wood, vegetated bars, or ledges to create a more sinuous flow path
3.Construct an inset floodplain to enhance overbanking
Alternative 2 – Construct New Channel with Airport In-Place
1.Construct ~4,000 ft of new meandering channel
2.Re-grade airport terrace fill to create a new floodplain
3.Build large woody debris features for habitat improvement
4.Work within the constraints of the airport and existing utility lines
Alternative 3 – Construct New Channel with Partial Airport Removal
1.Remove ~1,500 ft of airport runway for the new channel
2.Relocate sections of existing gravity and forced main pipelines
3.Construct ~4,800 ft of new meandering channel
Alternatives Ranking CriteriaObjective Desired Outcomes
Restore a more naturally functioning river and floodplain
Restore channel form in balance with hydrology and sediment supplyIncrease frequency of overbankingIncrease deposition of riverborne fine sediment and nutrients onto the floodplain.
Improve water quality by restoring natural stream and floodplain processes.
Reduce nutrient and fine sediment loads generated within the Project area or transported through the Project area.
Restore, enhance and protect aquatic and terrestrial habitat diversity and quality.
Enhance the habitat values of the river and floodplain for supporting native aquatic and terrestrial animals and plants.
Develop a cost-effective, timely and implementable design
Provide a cost-effective projectProvide a permittable projectMinimize time to project maturity and benefit
Floodplain Inundation
Modeling
760 cfs (2-yr Event)
Existing
Condition
0 acres
Future
Constructed
Condition
19 acres
Alternatives Ranking Criteria Example
Ranking
Scores
Channel & Floodplain Design
Design a channel and floodplain with an
appropriate morphology that is in balance
with the prevailing hydrology and sediment
regimes
• Measure transport throughout spring runoff
• Calibrate transport modeling with measurements
Bedload SupplyHow much bedload should the channel be able to
transport?
Measured &
Modeled
Transport
0.001
0.01
0.1
1
10
100
1000
0 100 200 300 400 500 600 700 800 900 1000
ENTRIX Meaured Bedload Transport (2006)
Modeled Bedload Transport - Wilcock (2001) Two-FractionCalibrated Method
Modeled Bedload Transport - Ackers & White (1973) with Proffitt &Sutherland's (1983) Hiding Function
Q (ft3/s)
Qs
(tons/day)
gravel t*rg = 0.01
sand t*rs = 0.03
Are t*c
values
reasonable?
Source: Wilcock and Kenworthy 2002
Upper Truckee River Effective Discharge - Based on Measured and Modeled Bedload During
Passage of a Sand Wave (High Transport Conditions)
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
50
74
98
122
146
170
194
218
242
266
290
314
338
362
386
410
434
458
482
506
530
554
578
602
626
650
674
698
722
746
770
794
818
Discharge (cfs)
Tota
l B
edlo
ad (
Tons)
Based on Ackers & White (1973) equation w ith
Proff itt & Sutherland's (1983) hiding function
applied at the Sunset Stables Bedload XS (RS
25+670) and all USGS gage #10336610 Mean
Daily Discharge from 1971-2005
Qeff = 398 cfs
Upper Truckee River Effective Discharge - Based on Measured and Modeled Bedload Without
Passage of a Sand Wave (Low Transport Conditions)
0
100
200
300
400
500
600
700
50
74
98
122
146
170
194
218
242
266
290
314
338
362
386
410
434
458
482
506
530
554
578
602
626
650
674
698
722
746
770
794
818
Discharge (cfs)
Tota
l B
edlo
ad (
Tons)
Based on Wilcock & Crow e (2003)
equation applied at the Sunset
Stables XS 26 (RS 24+540) and all
USGS gage #10336610 Mean Daily
Discharge from 1971-2005
Qeff = 398 cfs
Effective
Discharge
Analysis
Qeff = 400 cfs
Select
Design
Discharge
Equation: Huang and Nanson 1998 – (Qbf, S, n)
Bank Type Channel
Width (ft)
Moderately cohesive sand 44.5
highly cohesive sand 31.4
moderately vegetated and moderately cohesive sand 36.6
heavily vegetated and highly cohesive sand 26.7
Selected Design Width = 38 ft
How wide should the channel be?
Equilibrium Slope Analysis
0.00010.00020.00030.00040.00050.00060.00070.00080.00090.00100.00110.00120.00130.00140.00150.00160.00170.00180.00190.0020
20 30 40 50 60 70 80
Channel Width (ft)
Equili
brium
Slo
pe
2
3
4
5
6
7
Depth
(ft
)
Slope
Depth (ft)
How steep and deep should the channel be?
38 ft
Final Channel Design
Micro-
topography
Irregular
bends
Fill existing
channel
Construction – Summer 2008
Acknowledgements
• The City of South Lake Tahoe• The California Tahoe Conservancy• Mike Rudd - ENTRIX Project Manager• Charley Miller - ENTRIX• Chad Krofta - ENTRIX