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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?