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“REQUEST FOR PROPOSALS
FOR
OKANAGAN MAINSTEM FLOOD MAPPING”
Proponent’s Webinar
November 6, 2018
Shaun Reimer
& Brian Symonds
PROJECT AREA
&
OKANAGAN
LAKE
REGULATION
SYSTEM
(OLRS)
Okanagan Lake
Kalamalka &
Wood Lakes
Ellison Lake
Okanagan River
Skaha Lake
Vaseux Lake
Osoyoos Lake
OKANAGAN LAKE REGULATION
SYSTEM (OLRS):
Constructed in early 1950’s in
response to floods in 1940’s
Works:
4 dams (Kalamalka, Okanagan,
Skaha & Vaseux Lakes)
38 km of engineered channel
68 km of dikes
17 vertical drop structures &
5 sediment basins
Okanagan Lake Dam
Skaha Lake Dam
Vaseux (McIntyre) Dam
VDS 10
OLRS Structures
Okanagan Lake Dam
Vaseux (McIntyre) Dam
OKANAGAN LAKE - NET MONTHLY INFLOWS
-50.0
0.0
50.0
100.0
150.0
200.0
250.0
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Inf
low
- K
dam
3
SNOWMELT DOMINATED
INFLOW HYDROGRAPH
April – July: “Spring Freshet”
OKANAGAN LAKE DAM
“Okanagan Basin Agreement”
&
Operation of OLRS
OKANAGAN BASIN AGREEMENT
In the 1970’s the federal and provincial governments
jointly undertook a multi-year planning process to
develop a Comprehensive Frame Work Plan for
managing the water resources of the Okanagan to
“achieved a desirable balance
between the goals” of:
Economic Development
Environmental Quality
Social Betterment
Operate to balance competing interests
Flood Protection
Ecosystem / Environmental Recreation / Tourism
Water Use Demands
30.4 km engineered channel (86%)
2.1 km set-back dykes (~6%)
2.8 km natural river (~8%)
Okanagan R.
(Oliver reach)
WATER MANAGEMENT
OPERATIONAL CHALLENGES:
High natural variability of seasonal and
annual inflows and demands
Uncertainty of inflow volume forecasts
Extreme weather events (rainfall, wind, etc.)
Limited discharge capacities of dams
Limited river channel capacity relative to
instantaneous lake and river inflows
WATER MANAGEMENT
OPERATIONAL CHALLENGES (cont.)
Need to accommodate competing
economic (flooding, water supply),
environmental (sockeye, kokanee)
and social objectives at multiple
locations and times of year
Uncertainty of incremental impacts
of changes in flows, lake levels and
water temperatures on fish
populations during various life stages
(spawning, egg incubation)
KALAMALKA/WOOD
LAKE
• Surface Area: 3520 ha
• Normal operating range: 391.2 – 391.7 m, GSC
KALAMALK
A
LAKE
CONTROL
STRUCTURE 1 m3/s = 0.25 cm/day Max discharge ~ 6 m3/s (Note: Actual discharge dependent on lake level, gate settings and d/s constraints.)
Kalamalka Lake (Apr 1 – Aug 1, 2017)
2017 Previous maximum
Upper Quartile
Median
Target Maximum Elev:
= 391.7 m
(Datum: 386.122 m)
May 1
Jun 1 Jul 1
2017 Max Elev: 392.45 m (~ Jun 4)
Vernon Creek
at Outlet of
Kalamalka
Lake
2 m3/s
4 m3/s
6 m3/s
OKANAGAN
LAKE
Okanagan Lake Dam
Penticton Channel design capacity:
60 m3/s (1.5 cm/day on Ok Lk)
19
72
19
97
19
90
OLR
S
Co
nst
ruc
ted
20
17
19
48
VARIATION IN
OKANAGAN
LAKE ANNUAL
INFLOW
Range of annual inflow
volume :
0.23 m to 4.12 m
78 to 1400 million m3
KEY OKANAGAN LAKE ELEVATIONS:
FCL - Okanagan Lake: 343.66 m
2017 maximum (June 8): 343.25 m
2018 maximum (June 1): 342.69 m
Previous Post-OLRS maximums:
June 26, 1990: 342.87 m
July 13, 1997: 342.84 m
June 29, 1972: 342.75 m
Pre-OLRS maximum:
June 24, 1948: 343.07 m
OK LK FREEBOARD ALLOWANCE: 1970’s Ok Lk FCL incorporated the minimum freeboard
allowance of 2 ft (~ 0.61 m)
Freeboard allowances are used to account for uncertainties in
1:200-yr flood level, wave action, etc.
Wave heights on Okanagan Lake can exceed 1 metre
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
19
21
19
24
19
27
19
30
19
33
19
36
19
39
19
42
19
45
19
48
19
51
19
54
19
57
19
60
19
63
196
6
19
69
19
72
19
75
19
78
198
1
19
84
19
87
19
90
19
93
19
96
19
99
20
02
20
05
20
08
20
11
20
14
20
17
Infl
ow
Vo
lum
e (
mill
ion
s o
f cu
bic
met
res)
Okanagan Lake - Annual Net Inflow Volume (1921 - July 2018)
1981-2010 Normal
Source: BC River Forecast Centre, Ministry of Natural Resource Operations and Rural Development
2017
&
2018
ASP – Brenda Mines (1453 m elevation)
ASP - Mission Creek (1794 m elevation)
Okanagan Snow Basin Indices
2017 2018
01-Jan 79% 123%
01-Feb 79% 131%
01-Mar 86% 141%
01-Apr 105% 152%
01-May 147% 206%
BC River Forecast Centre Inflow Projections
Forecast Date
Forecast
Inflow
(Forecast
Date to July)
(kdam3)
% of 1981-
2010 Normal
Standard Error
(kdam3) Actual
Difference between
Forecast & Actual
Depth on
Lake (cm)
01-Feb-17 518 101% 120 935 417 121
01-Mar-17 485 98% 110 911 426 123
01-Apr-17 570 122% 108 843 273 79
01-May-17 554 147% 103 668 114 33
01-Feb-18 728 137% 120 854 126 36
01-Mar-18 719 140% 110 831 112 32
01-Apr-18 735 152% 108 776 41 12
01-May-18 779 200% 103 622 -157 -45
Each kdam3 is one million metres cubed and equivalent to 3.46 cm on Okanagan Lake
191 kdam3 inflow for week
ending May 13th = 55 cm
(21.6”) on Okanagan Lake.
Higher ‘one-week’ inflow
than in 2017.
Highest weekly inflow in
2017 was 135 kdam3 or 39
cm (15“). This was a new
weekly ‘record’ until 2018.
• Early Snowpack was low; No flooding was predicted.
• Monthly inflow forecasts based on the snowpack were also below average
through to April.
• Inflow models used historic weather and climate patterns and did not react
well to unprecedented March to May precipitation,
• Fisheries guidelines were overridden in April because of the ongoing
wet weather. Flows were increased dramatically prior to the complete
hatching/emergence of the sockeye in the Okanagan River.
• Even in early May, modelling did not project the lake going over annual
maximum target.
Part
ial w
eek
-25.0
0.0
25.0
50.0
75.0
100.0
125.0
150.0
Ja
n-0
7Ja
n-1
4Ja
n-2
1Ja
n-2
8F
eb-0
4F
eb-1
1F
eb-1
8F
eb-2
5M
ar-
04
Ma
r-11
Ma
r-18
Ma
r-25
Apr-
01
Apr-
08
Apr-
15
Apr-
22
Apr-
29
Ma
y-0
6M
ay-1
3M
ay-2
0M
ay-2
7Ju
n-0
3Ju
n-1
0Ju
n-1
7Ju
n-2
4Ju
l-0
1Ju
l-0
8Ju
l-1
5Ju
l-2
2Ju
l-2
9A
ug
-05
Aug
-12
Aug
-19
Aug
-26
Sep
-02
Sep
-09
Sep
-16
Sep
-23
Sep
-30
Oct-
07
Oct-
14
Oct-
21
Oct-
28
Nov-0
4N
ov-1
1N
ov-1
8N
ov-2
5D
ec-0
2D
ec-0
9D
ec-1
6D
ec-2
3D
ec-3
1
2017 Weekly Net Inflows Okanagan Lake (mil. m3)
Average
Current
Heavy precipitation in
early May led to earlier
and larger than normal
spring freshet inflow.
36.3 mil.m3 /week (60 m3/s)
2017 inflows after first week of
June well below normal due to
below normal June rainfall :
Reduced potential
duration of high lake levels
& exposure to storm events.
2017
Previous max
Upper Quartile
Median
2017 Level of
Okanagan
Lake
Okanagan Lake (May 1 – Jun 15, 2017)
Heavy rainfall:
~ 34 cm rise
in 1 week
~ 1.15 m rise in
lake level
(May 4 – Jun 9)
• We could “see it coming” this year and lake was drawn
down as per guidelines;
• Inflow forecasts based on that snowpack fit a more usual
pattern even with high snowpacks;
• Fisheries guidelines were overridden in April 2018;
• Outflow from Okanagan lake was reduced in mid-May to
account for unprecedented downstream tributary flow into
the Okanagan River;
2018 Operational Complications • Oliver flows peaked higher than 2017 (108 m3/s or 3800
cfs).
• Difference between flows at Penticton and Oliver were
up to 70 m3/s (2472 cfs) for a brief period but a
difference greater than 45 m3/s (1590 cfs) was
maintained for several weeks.
• Cold and wet La Nina winter transitioned into warmest
May on record…
Mid-May differential
between Penticton and
Oliver flows peaked at
approximately 70 m3/s –
highest know to date;
Okanagan R. near Oliver
Okanagan R. at Penticton D
isch
arg
e (
m3
/s)
Dis
ch
arg
e (
m3
/s)
Ma
y 1
M
ay
1
Jun
1
Jun
1
Design Discharge
= 60 m3/s
Design Discharge
= 105 m3/s
60 m3/s
20 m3/s
Note: Max difference in flow
between Pen & Oliver > 65 m3/s
80 m3/s
19
72
19
97
19
90
OLR
S
Co
nst
ruc
ted
20
17
19
48
Earlier freshets will complicate lake level management
2017 & 2018 peaks much earlier than previous ‘flood years’. Trend is
problematic for OLRS operations.
2017
2018 1997
1948
1972
1990
2012
May 1
Ju
l 1
OSOYOOS LAKE
& ZOSEL DAM
Osoyoos Lake straddles the international boundary in south central British Columbia and north central Washington
Zosel
Dam
International
Boundary
N
Osoyoos Lake
Zosel Dam
37
Zosel Dam
Osoyoos Lake
Cross Channel
Cross Channel
between
Okanogan
and
Similkameen
Rivers
(South of
Oroville)
Average Flows in
Similkameen and Okanagan Rivers
38
Average Annual Flow:
Similkameen R – 64.5 m3/s
Okanagan R – 17.8 m3/s
39
Zosel Dam (near Oroville)
Spillway
Control Gates
& Fish Ladders
40
1. Normal:
Gates
Controlling Lake
Level
2. High Inflows:
Gates
Freeboarding
3. Moderate
Similkameen R
Backwater:
Gates F/B while
B/W slowing
outflow
4. Extreme
Similkameen R
B/W: Flow
reversal
1.
2.
3.
4.
Backwater
Condition at
Zosel Dam
Non-Backwater Condition
Backwater Condition
42
2018
Osoyoos
Lake Levels
and
Historic
Range
916.0 ft
913.0 ft (spillway crest elevation)
2018
Historic Range
2018 Max Level:
916.41 (May 11/12)
Osoyoos Lake
Okanagan R near Oliver
Ma
y 1
Dis
ch
arg
e
Ma
y 1
6
Ma
y 8
100 m3/s (3,530 cfs)
80 m3/s (2,830 cfs)
2018 Max:
~ 916.41 ft
(May 11/12)
Ma
y 1
2
44
Similkameen R. at
Nighthawk
Okanogan R. d/s
of Zosel Dam
Osoyoos Lake 2018 Max:
~ 916.41 ft
(May 11/12)
Similkameen River at Nighthawk
Discharge 2018 & 2017
45
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
45,000
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Dis
char
ge (
cfs)
Discharge Range (1929-2017)
Mean Discharge (1929-2017)
2018 Discharge (cfs)
2017 Discharge (cfs)
2018 Max. Discharge:
= 31,200 cfs (May 10)
2017 Max Discharge:
= 18,700 cfs (June 1)
Questions?