Flood Controls and Protection

As a means of celebrating the role of engineering and geosciences for the 90th year of APEGM’s history, the Heritage Committee began a series of articles in 2010, under the general theme of “Liquid Assets” that link water to the economic and social development of the province. This is a follow-up article in light of the spring and summer of 2011, when the liability side of water’s balance sheet affected the lives of Manitobans and the contribution of engineering and geoscience to the flood control and protection system have been both recognized and questioned. From the experience of 2011 Manitobans, and Winnipeggers when they gaze beyond the perimeter highway, now have an enhanced awareness of the realities of living in the bottom of a former glacial lake.

Awareness of vulnerability to flooding hasbeen with Manitobans since before the Province’s entry into confederation. The spring of 1826 brought the greatest flood toinundate the valley and Red River Settlement, estimated by engineers on thebasis of journals and eye-witness recollection to have risen to an elevation of764.87 ft. above sea level. The 1852flood crested two feet lower than in 1826, but it caused more damage in thesettlement due to urban growth and rapid rise due to a number of large icejams. In May of 1950 the RedRiver crested at 757.87 ft. at James Avenue, creating a lake seven miles wideat Winnipeg's southern limits.

One of the earlier engineering papers onthe mitigation of flooding was authored by D.L. McLean, who had previously beena design engineer on the Greater Winnipeg Water District aqueduct. It was publishedin 1920. Since then engineers have continued to be instrumental in implementingthe Province’s system of flood control and protection. That contribution hasbeen acknowledged throughout the system’s development, and was recognized bythe association (APEM at the time) during the Centennial of Engineering inCanada in 1987. The physical reminder is a plaque dedicated by theLieutenant-Governor of Manitoba at the 1987 annual meeting.

The wording of the dedication of the plaquewas:

“On the occasion of the Centennial of The Engineering Profession inCanada and to recognize the Profession’s service to the citizens of theProvince and its contribution to the development of the Province, theassociation of Professional Engineers of Manitoba has chosen to honor theengineering undertaking which exemplifies that contribution over the past 100years.

By Reducing damage and the threat to lives and property fromrecurring floods in many parts of the Province, the Manitoba Flood Control andProtection System has greatly contributed to the peace of mind and the socialand economic well-being of a vast number of the citizens of our Province. Theworks, the operational procedures and the emergency response mechanisms whichcomprise the system are deemed to epitomize the obligation of ProfessionalEngineers to ensure the safety and comfort of people in all engineeringundertakings.

October 19, 1987

Dedicated by The Honourable GeorgeJohnson, Lieutenant Governor ofManitoba”

Other wording on the plaque describesfeatures of the system as it was in 1987. It included; the Red River Floodway,Shellmouth Dam, Assiniboine [Portage] Diversion, Seine River Diversion,Fairford Control Works, Diking Systems, and Flood Forecasting. The wording canbe accessed at the Heritage Committee section of the APEGM website www.apegm.mb.ca/Heritage/index.html. A copy of the1920 paper by D.L. Mclean is also available in that section.

Since 1987

The descriptions on the 1987 plaque providedan overview of the system at that time. Most of them have since become familiarto Manitobans. Since then we haveexperienced the 1997 “Flood of the Century” and are aware that the Red RiverFloodway has been expanded. In 1987 eight communities in the Red River Valleywere protected by ring dikes. After the 1997 flood twelve additionalcommunities were protected and 1800 homes, businesses and farms in the valleywere either raised onto pads or protected with individual ring dikes. Theeffectiveness of the flood control works in the Red River Valley was evidentduring the spring of 2011 when very little flood damage occurred even thoughthe flood was larger than the historic 1950 flood.

But therehave been other projects outside of the Red River Valley that have not garneredas much attention. The first two below were mentioned in the 1987 plaque:

Seine River Diversion The first major floodwater diversion constructed in Manitoba, the SeineRiver Diversion, diverts excess Seine River flows of up to 4270 cfs from apoint upstream of Ste. Anne to the Red River near St. Adolphe. The diversionwas constructed in 1962 at a cost of $1.8 million to provide flood controlalong the Seine River through and below Ste. Anne.

Fairford Control Works Located at the outlet of Lake Manitoba on the Fairford River, theFairford Control Works together with upstream and downstream channelimprovements were constructed in 1961 to control Lake Manitoba levels within amuch narrower range than that which occurred historically. The controlstructure doubles as the PTH #6 highway bridge. Stop logs are installed orremoved to control the flow.

Carman Diversion A diversion of the Boyne River around the Town of Carman was completed in1991. Before the diversion was constructed Carman experienced flooding in 1893,1923, 1970, 1974, and 1979. The 1979 flood caused damages of over $3 million. The$6 million diversion diverts flood water from the Boyne River west of Carmanthrough a 9.8 km channel that exits into the Norquay Channel. It has been veryeffective in flood prevention.

Ste. Rose du Lac Following a 1975 flood from the Turtle River in Ste. Rose du Lac a dikingsystem was constructed through the town. A flood in 1986 overtopped these dikes.The dikes have since been upgraded to provide protection against a one in 100year flood event. The dikes were raised and sandbagging was necessary toprotect Ste. Rose du Lac in 2011

The Pas Area A series of dikes along the Saskatchewan River and Carrot River in thevicinity of The Pas has been constructed to protect agricultural andresidential areas. The Carrot River is located south of the Saskatchewan Riverflowing easterly. It is generally about 10 km south of the Saskatchewan andjoins that river just before it reaches The Pas. The Carrot River hasapproximately 39 km of dikes. The Salt Channel which protects the western boundaryof the Carrot valley area has 34 km of dikes. Together with the Pasquia Riverdikes they protect 57,000 hectares of farm and residential land.

Rock Lake, Pelican Lake Controls Completed in 1991, the Pelican Lake Controls include a diversion channelfrom the Pembina River to Pelican Lake and control structures. The diversionchannel brings water to the lake to raise low lake levels and drains water fromthe lake to prevent high water levels, providing improved regulation of waterlevels. At Rock Lake a weir and an outlet channel to the Pembina River havebeen built, along with dikes on the west side of the lake to protect farmland.

Assiniboine River Diking Systems Downstream of the Shellmouth Dam (the reservoir formed by the dam, theLake of the Prairies, extends into Saskatchewan) the Assiniboine River meandersin the bottom of the deep river valley that was formed by the melting glaciersapproximately 10,000 years ago. The valley is subject to flooding when theAssiniboine River spills over its banks as happened in 1976 and in 1995. TheTown of St. Lazare, 60 km downstream of the dam, has been protected by a ringdike.

Further downstream at Brandon the Assiniboine flows in the deep valley onthe north side of the City. While most of the City is located on the higherelevations above the valley floodplain, industrial, commercial, residential andrecreational properties and facilities exist in the floodplain. Most notable isthe Brandon Flats area located on the south side of the river between FirstStreet and 26th Street. Prior to 2011, flood prone properties wereprotected to varying degrees, but generally not against a 100 year flood.

East of Brandon the Assiniboine River breaks out of the glacial valleyinto the Assiniboine River delta east of the Manitoba escarpment and enters theflat remnants of Glacial Lake Agassiz. East of the Portage Diversion and theCity of Portage la Prairie to just east of Baie St. Paul (near St. FrancoisXavier) there are 67 km of diked channel for a total of 134 km of dikes. The dikeswere first constructed in 1912. They were reinforced in 1950 and againfollowing the 1997 flood. They protect farmland, farms, and rural residences aswell as the communities of Elie, La Salle, Sanford and Starbuck.

Souris River The Souris River begins in Saskatchewan, runs south into North Dakota, andreturns to Manitoba, joining the Assiniboine River near Treesbank. In NorthDakota the River passes through the City of Minot and many smaller centers. InManitoba the Souris passes through the towns of Melita, Souris, and Wawanesa. ThoseManitoba communities had dikes along the Souris before 2011.

The “Perfect Storm” of 2011

Despitethe pre and post 1987 measures, with the events of 2011 we have come to realizethat Manitoba is vulnerable to the impact of major flood events. While thesystem performed well for the Red River Valley, unusually high runoff on theAssiniboine and Souris Rivers, exceptional rainfall in Saskatchewan, and highwater levels in Lake Manitoba and Lake St. Martin converged to requireemergency measures and caused devastation – particularly on Lake Manitoba andLake St. Martin.

At Brandon, to address the predictions made in February, the City raised approximately5 km of dike by about 0.6 m, thought to be 0.3 m above the predictions for the2011 spring flood. But it far exceeded all expectations and required anenormous additional diking effort including the assistance of the CanadianArmy. The Assiniboine had several crests; the largest had a flow of 37,100 cfs representinga 300 year flood. While the dikes protected the low lying areas, the risk of abreach required evacuation of the Flats area for several weeks and traffic wasdisrupted on the major access roads to the city.

East of Portagela Prairie where the design capacity was a flow of 18,500 cfs, the dikes wereat considerable risk and the Canadian Army was called upon to assist withstrengthening and inspection. Because of the softened condition of dikes due topersistent wet weather some sections were reinforced with sandbags delivered byhelicopter. Because the flow in the Assiniboine at Portage la Prairie was 52,400cfs (34,500 beyond the downstream capacity) the Portage Diversion was upgraded todivert a peak of 34,000 cfs to Lake Manitoba, much beyond its 25,000 cfs designcapacity. The emergency over capacity flow required evacuations along thediversion for safety.

As anotheremergency measure to prevent overtopping of the dikes a breach in the south dikewas made at the Hoop and Holler bend to release water toward the LaSalle River.While only approximately 400 cfs were released, the deliberate release andflooding of lands south of the river illustrate the grave concern along theAssiniboine between Portage la Prairie and Baie St. Paul.

Therewere three crests on the Souris River, the first on April 9, 2011. Each timedikes were raised and reinforced. The last crest was caused by a majorrainstorm in Saskatchewan near the middle of June. The flood devastated theCity of Minot where 11,000 people were displaced and 4,200 residences wereinundated, many to roof level.

InManitoba, dikes were raised by as much as two metres above the already raisedand reinforced levels and once again the Army was called upon at the lastminute to assist. The peak flow exceeded 30,000 cfs, in the range of a 300 yearflood. The temporary dikes held and averted a disaster similar to what occurredin Minot. Extensive damage was caused to roads, bridges, and otherinfrastructure. Most notable was the loss of the famous Souris swinging bridge.As the crest approached it was feared the bridge would be ripped from itsmoorings which could have damaged the dikes on each side of the river. One endof the bridge was severed as a precaution.

Thediversion of water to Lake Manitoba, along with high flows in the WaterhenRiver from Lake Winnipegosis and in the Whitemud River has caused an enormousflood all around Lake Manitoba and Lake St Martin. At this time, July 21, 2011,Lake Manitoba is above 817 feet above sea level. Many stakeholders around LakeManitoba, including farmers, ranchers and cottagers feel the ideal level is810.5 – 812.5 feet. That range was adopted by the Lake Manitoba RegulationAdvisory Committee in 2003. That leaves the July 2011 level at 5.5 - 7 feetabove optimum.

Tocompound the situation a fierce windstorm from the northwest on May 31, 2011caused widespread destruction even as protective measures were being undertakenprior to the rise in lake level. Winds were 75 kilometers per hour with guststo 100 kilometres per hour. The destruction to the farms and ranches and thecottage communities from Twin Lakes in the south to Laurentia Beach and JohnsonBeach in the north was devastating and still has not been fully assessed asaccess for roughly two thirds of the cottages, including permanent residents,was only restored in mid July. Delta Beach at the south end of the lake wasdevastated.

Dikingagainst the high water and potential windstorms continues for the many homesand communities all around the lake. While three weeks of dry and hot weather inJuly have assisted and Lake Manitoba levels have stabilized for several days,the predicted peak of 817.5 has not yet been assured. The flood resulting from highlake levels and wind has been described as a once in 2000 year event.

LakeManitoba drains through the Fairford Control Structure described above, intoLake St. Martin and the Dauphin River to Lake Winnipeg. With Lake Manitoba athigh levels the flow through the Fairford Control Structure is at 20,800 cfscompared to a normal flood flow of 6000 cfs in summer and 3500 cfs in winter. LakeSt. Martin and the Dauphin River have also been flooded. Four First NationCommunities; Fairford First Nation; Little Saskatchewan First Nation; Lake St.Martin First Nation; and Dauphin River First Nation have been evacuated for upto three months with no end in sight. Lake St. Martin is at elevation 806,three feet above the historic 1955 peak of 803 and 6-8 feet above the desirablerange of 798-800.

The Lakesare predicted to remain at flood levels well into winter and approximately 2000residents and cottagers are not permitted into most areas except for day visitsto retrieve belongings. Thousands of cattle have been moved to higher ground orout of the area for feed as the hay crops are flooded.

Moving Forward

Theexperience of the many necessary emergency actions and the devastation from theoutcomes of the 2011 flooding in Manitoba tells us that the job of effectiveflood control and protection is not yet finished. After the 1950 flood thefocus of flood protection was on protecting Winnipeg from future floods. Afterthe 1997 Red River flood the focus was on increasing flood protection forWinnipeg and the whole Red River Valley. Both of these efforts have proved verysuccessful. With the 2011 flood the focus has turned towards increasing floodprotection along the Assiniboine and Souris Rivers and on Lakes Manitoba andSt. Martin.

A majorstudy on an up to 9000 cfs channel parallel to the Dauphin River from Lake St.Martin to Lake Winnipeg has been completed and released in late July. It includes a seemingly optimisticconstruction completion date of November 1, 2011. The 8 km long channel fromLake St. Martin to Big Buffalo Lake, from which the water would flow throughexisting streams and return to the Dauphin River near Lake Winnipeg isestimated to cost $100 million. The channel would go through very wet bog andthe location is only accessible for equipment by crossing Lake St. Martin bybarge. If emergency approval and funding from the federal government isobtained, environmental impact studies would have to be made duringconstruction to meet the November date. Opposition has already been expressedby the Dauphin River First Nation and the community of Dauphin River over increasedflows and the effect of river levels on access, the Dauphin River, iceconditions and the fishery.

TheFairford Control structure is operating at maximum capacity and the new channelwill only help to reduce water levels by making it possible to operate thecontrol structure at a higher capacity during the winter when the flow normallyhas to be reduced to prevent flooding along PR 513 and at Dauphin River due toice conditions in the Dauphin River. It is predicted the lake could be drawndown to elevation 813.1 by spring, rising to near 814 with spring runoff, stillseveral feet above optimum with possible use of the Portage Diversion looming.

A secondphase would see a new bypass channel from Lake Manitoba to Lake St. Martinestimated to cost $60 million. The channel would increase the flow capacityfrom Lake Manitoba to Lake St. Martin. A third phase is to increase thecapacity of the bypass channel. These necessary works are only in the conceptstage. Providing effective controlled drainage of the Lake Manitoba system, andby extension the Lake Winnipeg and Nelson River system, will be necessary ifManitobans are to preserve and maximize the asset of our water supply.

One of the earlier engineering papers onthe mitigation of flooding was authored by D.L. McLean, who had previously beena design engineer on the Greater Winnipeg Water District aqueduct. It was publishedin 1920. Since then engineers have continued to be instrumental in implementingthe Province’s system of flood control and protection. That contribution hasbeen acknowledged throughout the system’s development, and was recognized bythe association (APEM at the time) during the Centennial of Engineering inCanada in 1987. The physical reminder is a plaque dedicated by theLieutenant-Governor of Manitoba at the 1987 annual meeting.

The wording of the dedication of the plaquewas:

“On the occasion of the Centennial of The Engineering Profession inCanada and to recognize the Profession’s service to the citizens of theProvince and its contribution to the development of the Province, theassociation of Professional Engineers of Manitoba has chosen to honor theengineering undertaking which exemplifies that contribution over the past 100years.

By Reducing damage and the threat to lives and property fromrecurring floods in many parts of the Province, the Manitoba Flood Control andProtection System has greatly contributed to the peace of mind and the socialand economic well-being of a vast number of the citizens of our Province. Theworks, the operational procedures and the emergency response mechanisms whichcomprise the system are deemed to epitomize the obligation of ProfessionalEngineers to ensure the safety and comfort of people in all engineeringundertakings.

October 19, 1987

Dedicated by The Honourable GeorgeJohnson, Lieutenant Governor ofManitoba”

Other wording on the plaque describesfeatures of the system as it was in 1987. It included; the Red River Floodway,Shellmouth Dam, Assiniboine [Portage] Diversion, Seine River Diversion,Fairford Control Works, Diking Systems, and Flood Forecasting. The wording canbe accessed at the Heritage Committee section of the APEGM website www.apegm.mb.ca/Heritage/index.html. A copy of the1920 paper by D.L. Mclean is also available in that section.