Nooksack River International Task Force

Nooksack River International Task Force
April 2003 Update
Task Force Co-Chairs:
Neil Peters
Ministry of Water, Land and Air Protection
Richard Grout
Washington Department of Ecology

Presentation Outline
• The Flood Hazard
• Task Force Activities 1991 to 2002
• Flood Model Animation – Impacts of 1:200 flood in
Sumas Prairie, Abbotsford
• Next Steps
• Issues
• Questions

Sumas Prairie
Everson
Deming
Mt Baker

Barrowtown
Pump station
Interceptor Dike
Overflow
Corridor
Overflow
Reach

1995 Airphoto of Overflow Reach
Massey Road
1997 Erosion Site
Emmerson Road
Everson
Overflow Locations

Nooksack Overflow Flood Damages
• Everson overflow has occurred 14 times in
67 years
• November 1990 total flood damage $21.8
million (more than $7.4 million due to
Everson overflow)
• November 1995 total flood damage $4
million (all in Whatcom County)
• Average Annual Damage est. $2.5 million
($1.1 million or 45% due to overflow)

Hydrographs at Deming - 1990 and 1995
and estimated 1:200 flood
70000
60000
200-Year Design Flood Hydrograph for Nooksack River at Deming
200-Year Design Flood Hydrograph
Nov 1990 Flood (Rating Curve 19)
Nov 1990 Flood (Data from Paula)
November 1995 Flood
50000
Discharge in cfs
40000
30000
20000
10000
0
0 24 48 72 96 120 144
Time in hours

Highway I-5 I 5 at Ferndale November, 1995
(looking south west)

Highway I-5 I 5 at Ferndale November, 1995
(looking south west)

November 1990 Flood
Sumas,WA and Huntingdon, BC

November 1990 Flood
Sumas,WA and Huntingdon, BC

November 1990 Flood
Looking South to Vye Road and the Southern BC Railway
Breach in Railway

November 1990 Flood - Looking East Along Trans
Looking East Along Trans-
Canada Highway at Whatcom Road Interchange
Interceptor Dike

The Nooksack River Avulsion Threat
• An avulsion (major channel relocation) to
Sumas and Abbotsford has been estimated to
have a 1 in 500 annual probability (Klohn
Leonoff, 1993)
• In the overflow reach, the land slopes away
from the river bank towards Sumas
• Severe bank erosion (about 250 metres)
during a 1:100 year flood event could cause
an avulsion
• 1993 report concluded potential damage
could exceed $100 million

1997 Airphoto of Overflow Reach
1997 Erosion Site #1

Bank Stabilization Works
Site 1 - upstream of Everson - 1997

Nooksack River International Task Force
• American Members
– Washington State Department of Ecology
– Whatcom County
– Federal Emergency Management Agency
– US Army Corps of Engineers
– City of Sumas
– National Weather Service
– US Natural Resource Conservation Service
• Canadian Members
– Ministry of Water, Land and Air Protection
– City of Abbotsford
– Environment Canada

NRITF - Success Highlights
• Emergency Response
– international weather radio - Aldergrove
– joint emergency measures planning
– advanced early warning system
• Floodplain Management
– City of Abbotsford floodplain bylaw
– Whatcom County land and easement
acquisition program

NRITF - Success Highlights (cont’d)
• Overflow Reach - Channel
Stabilization
– 1997 erosion protection works at
Riverberry and VanDallen sites
• Comprehensive Planning
– Whatcom County CFHMP completed
(detailed hydraulic modelling underway)
– Sumas River Flood Modelling Project

Barrowtown
Pump station
Sumas Flood
Model Area
Interceptor Dike
Overflow
Reach

Sumas Prairie Contour Map (1 metre contour interval for each colour)
Barrowtown Floodbox and Pump Station
Time
US/Canada border

Sumas Prairie – Max Extent of 1:200 Overflow
Trans-Canada Highway
W.L. = 8.5 m
Typical flood
depths 1 to 3 m
W.L.= 4m
Maximum
flood depth
about 4
metres
Crest of Interceptor
Dike = 7.0 m approx.

1:200 Event Modeling - Potential
Impacts in Sumas Prairie
• Trans-Canada Highway inundated by
deep water for at least 9 days
• 1,160 parcels flooded – primarily
farming (dairy, livestock), rural
residential
• Order of magnitude estimate for
flood damage (not including damage
to utilities, roads and other
infrastructure) is $130 million

Next Steps
• Phase 1 Modelling
– Evaluation of the hydraulic effects of
the highway bridge and Lagerway dike
at Everson
– Simulation of the 1:200 year flood on
the Lower Nooksack assuming existing
flow split
– Simulation of the Nov 1990 (approx.
1:50) and 1:200 floods assuming that
overflow is prevented

Next Steps (cont’d)
• Task Force meeting on May 13 th to
discuss the scenarios and options to
be modelled in Phase 2
• Phase 2 Modelling - Evaluation and
analyses of alternatives
• Raising dikes
• Floodway storage
• Partial control of overflow
• Designated floodways
• Sediment management
• Increased pump capacity (Barrowtown)

Structural Options to Reduce Flood
Damage in Abbotsford (Preliminary Analysis)
• Dredge Outlet to Fraser River
– Increases capacity of outflow channel
– small benefits for high cost (1M cubic metres
to be removed)
• New Pump Station at Barrowtown
– small benefits for high cost (approx. $45M for
doubling existing capacity)
• Internal Floodways
– delivers water quicker to gravity floodboxes
– provides benefits for smaller events (1:25) but
increases damage for larger floods (1:100)

Potential Floodway Locations

Issues
• Managing the flow split
– mitigating downstream impacts on
Nooksack River if overflow reduced
– monitoring sediment deposition and
channel change
• Role of Task Force
– Whatcom County and City of
Abbotsford have primary decision
making responsibility
– Public consultation processes required
– Should role of Task Force be to
recommend and “sell” best alternative?
• Funding
– for technical studies - to fully evaluate
alternatives
– for public process and capital works

Questions?
US - Canada
Border at Sumas
November, 1990