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Extreme rainfall during the summer of 2010 caused Fishing Lake to be at the highest recorded fall water level going into freeze up. The combination of high water levels, saturated conditions in the watershed and above-normal snow accumulation gave rise to a significant threat for a flood event for the spring of 2011. To prepare, the Saskatchewan Watershed Authority developed a plan to minimize potential damages and implemented the following flood protection measures:
- raise low areas on berms to the original design standard for flood protection;
- construct a channel downstream from Hazel Lake to hasten the outflow of water from Fishing Lake
- undertake emergency sandbagging to protect properties at risk
- assist Fishing Lake First Nation to resolve flooding issues on the reserve.
Although faced with tight timelines and difficult weather conditions, construction of flood protection works was completed prior to spring runoff. On April 30, 2011, Fishing Lake peaked at elevation 530.92 metres (m), which exceeded the previous highest recorded elevation by 0.30 m. The flood protection measures that were put in place were effective in preventing flood damage around the lake.
Raising Berms
When the temporary berms were initially constructed for emergency purposes in 2007, not all areas were built to the same elevation and some areas had settled over time. To ensure the berms met the intended standard for flood protection, low areas of the existing berms were raised to design elevation.
Most of the berms were built on the public reserve; however, under the municipal states of emergency, the berms in some areas crossed private lands. Because of the short timeline involved to allow access to repair and raise the berms, the Watershed Authority expropriated easements on 18 properties where berms crossed onto private land. These easements allow for the berm to remain and for access to maintain the berms on the private lands.
Channel Construction
To increase the outflow capacity from Fishing Lake during flood events, construction of the 12.7 kilometre (km) channel downstream of Hazel Lake was built within three reaches: Hazel Lake to White Sand Lake, White Sand Lake to Dog Lake, and Dog Lake to Newburn Lake.
The channel will not contribute to additional volumes of water downstream above what would occur under natural conditions, but will accelerate the drawdown of Fishing Lake to normal water levels following flood inflows. The channel will only carry water when Fishing Lake is at flood stage and cannot be used to lower the lake below its normal full supply level. The outflow from Fishing Lake flows into the Whitesand River, which ultimately empties into the Assiniboine River near the Province of Manitoba.
Saskatchewan and Manitoba reached an agreement on the operational conditions for the channel to address concerns that the project could contribute to flood damage in Manitoba.
The gates on the control structure on the channel were opened on August 2, 2011, after flooding had finally subsided in Manitoba. The gates will remain open until the lake recedes to 530. 0 m.
Further channel work continues as the Watershed Authority works on the installation of erosion protection measures, fencing, cattle crossings and clean up.
Fishing Lake First Nation Flooding
The Fishing Lake First Nation experienced flooding problems on their lands due to high local run-off. In consultation with the First Nation, the Watershed Authority worked with the First Nation to install culverts and improve drainage to prepare for the spring 2011 runoff.
Sandbagging
Several meetings with local governments took place to identify properties at risk and to develop plans to provide flood protection. Generally, the emergency response plan involved sandbagging properties not protected by berms and at risk of flood and erosion damage, and the supply of pumps to remove local runoff from behind the works.
The Watershed Authority arranged for the purchase of large sandbags, access to material from borrow pits, and sandbag filling devices. In total, 15,000 large one-ton sandbags were used along 3.8 km of shoreline, and varied in height from one to three bags high.
Once water levels recede, a meeting will be held with local governments to develop a plan to remove the sandbags.
Long-Term Flood Protection
Given the decision of local governments to have the berms upgraded to become a permanent flood control measure, the Watershed Authority was tasked with securing the necessary regulatory approvals to upgrade the berms to permanent status.
All regulatory approvals have been obtained to upgrade the berms to permanent status with the exception of the Department of Fisheries and Oceans (DFO) permit. DFO is currently reviewing the fish habitat compensation plan submitted by the Watershed Authority.
In the fall of 2010, the Watershed Authority completed repair to sections of berms that had been subject to severe erosion. The repair work upgraded these sections of berms to essentially the permanent status.
Construction and completion of these works will complete the government's existing commitment to provide long-term flood protection for the communities around Fishing Lake and address the unusual and urgent flood risk presented earlier this year. These efforts will provide the long-term flood protection needed to support future development in the affected communities and also protects communities for a 1 in 500 flood event.
Maps and Photos
Project Proposal for Permanent Berm Upgrade
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