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A river is a natural eco-system supporting a variety of plant
and animal life. It is not a ditch! The health and life of a river
must be taken into account in any project that impacts it. Any
drainage or flood protection project must consider not only the
5% of the time when the river is capable of flooding but also
the 95% of the time when the river needs strong water levels to
support life and provide recreation and enjoyment.
The Red River Floodway cuts across the Seine River just south
of the City of Winnipeg. When the Floodway was built, a large
pipe (inverted siphon) was buried under the Floodway to allow
the Seine River to flow into the city. Normal river capacity is
about 13 cubic meters per second (CMS). The siphon capacity is
about 4.5 CMS so the Seine River downstream of the floodway will
never again see a natural spring flush. A normal spring flush
removes most debris and deadfall and soaks the banks and lowlands.
The lack of a flush may affect plant life in ways we don't realize.
It is part of the natural cycle that helps the riparian zone thrive.
The siphon was built with the single-minded goal of protecting
the city from floods and for that we are grateful. However it
requires monitoring to ensure that as much water as possible is
getting through to keep the Seine River alive within the City.
The inlet can become plugged with debris limiting the water volumes
entering the siphon. S.O.S. and Water Resources Branch reduced
this problem when a log-boom was placed across the river to hold
debris back from the inlet. Constant monitoring of the inlet is
still required to make sure the inlet grill is not blocked with
reeds, branches, garbage etc. When it is blocked, SOS and other
concerned citizens can call the Manitoba Water Resources at 945-0168
or 945-8885.
The output at the outlet needed to be monitored to ensure that
all the water entering the siphon continues through to the outlet
and does not just leak into the Floodway. For several years it
was known that the pipe was leaking and causing lower river levels
inside the city. S.O.S. had been monitoring the siphon and keeping
in touch with Manitoba Water Resources branch to encourage them
to repair it. It seemed the section of the Seine River within
the City of Winnipeg had been orphaned by the siphon.
In January 1994, SOS wrote to MP Ron Duhammel requesting funds
from the Canada/Manitoba Infrastructure Program to repair the
leaking siphon. We received a request for details and a cost estimate.
SOS then met with Provincial Water Resources to determine the
extent of the problem, and find out what plans there were to repair
it. We were informed that tests were done in 1990 showing that
the siphon was leaking approximately 0.75 cubic feet per second
(CFS). Tests about a year later showed the leakage had increased
to approximately 0.80 CFS. Estimated cost to inspect and repair
the siphon was $110,000. An official of the Provincial Water Resources
stated that the province wanted to do another leakage test "if
conditions are ideal" and if warranted, they would "de-water
and inspect" the siphon. He also wanted to wait until the
City completed the Seine River Task Force Study (finished in 2000)
before negotiating with other levels of government on cost sharing.
The Infrastructure Program expired several months later, before
the province supplied the required information to request funding.
On August 11 & 14, 1995, SOS discovered the siphon was completely
empty and advised officials of the Provincial Water Resources
Branch. This was an ideal time to inspect the siphon "for
free" without the need to "de-water" it. Any accumulated
debris blocking water flow could also be removed at this time.
This opportunity passed without action.
Three years later on September 23, 1998 SOS again observed a dry
siphon and contacted Water Resources but due to cost constraints
this opportunity too was lost, despites SOS's efforts to get provincial
politicians to give the job priority.
On September 30, 1998, a consultant retained by SOS for the Riffle
Project inspected the siphon along with SOS members. He estimated
8.0 to 10.0 CFS of water was flowing into the siphon while nothing
was flowing from the outlet! A flow of about 8.0 to 10.0 CFS was
observed boiling up through the ground into the center of the
Floodway from the leaking siphon. During the four years SOS was
trying to get the siphon fixed, the leakage increased from 0.8
CFS to 10.0 CFS (a 10 fold increase). Our consultant convinced
Water Resources staff to visit the siphon with him and witness
the problem first hand, and then wrote a letter to higher authorities
requesting action.
Finally SOS contacted the Winnipeg Free Press and on October 14,
1998 they ran a front-page photograph and article
that explained the problem with the siphon. In January 1999 Water
Resources staff inspected the siphon and found the leaks and resulting
erosion. Later that year a decision was made to repair the existing
60" corrugated metal pipe by pulling a new 48" plastic
liner into it. Early estimations were as high as $1 Million.
Nelson River Construction completed the Siphon repair during
the winter of 1999-2000 at a cost of $620,000. Improved flows
were noticed during spring and summer of 2000.
Some people have speculated that heavy flows through the siphon
during the flood of 1997 caused erosion surrounding the siphon
pipe, which increased the leak. Some also speculate on the damage
that might have resulted if the siphon damage had been greater.
Could it have undermined the floodway itself?
Some other ideas for improved flows:
The siphon inlet was designed to protect the city from being flooded
by the Seine River, with no regard to low water levels. When the
water south of the siphon inlet is above a certain level, water
flows over a concrete lip into the floodway, bypassing the city.
SOS believes that this lip may be set too low and normal full
summer flows are being diverted into the floodway when there is
still capacity in the river (but none in the siphon).
Increasing the capacity of the siphon would be a very costly project,
but there may be an inexpensive alternative: raise the siphon
overflow lip 10 or 12 inches so water would not be diverted into
the floodway until levels are 10 or 12 inches higher. There is
enough capacity in the Seine River south of the floodway to hold
this backwater. This modification to the siphon inlet would create
a mini reservoir, retaining some of the high water for later release
through the siphon into the city.
HAROLD THWAITES is a lifelong resident of St. Vital,
River lover, Paddler, SOS Past President, past member of Seine
River Task Force Advisory Committee and Hydrology Subcommittee.
 see
also: Disappearing River (Canadian
Geographic)
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