May 20, 2011
Flood Bulletin #54
- Work to close the controlled release at the Hoop and Holler Bend on the Assiniboine River began at noon today. It is expected to take a few hours to completely close the spill point.
- The closure of the controlled release is possible because, although they are still very high, flows into the Portage Reservoir are dropping and the Portage Diversion and Assiniboine River dikes are better able to manage the flows.
- The closure cannot yet be considered permanent. Due to continued high flows on the Assiniboine River, ongoing concerns with the integrity of the Portage Diversion and Assiniboine River dikes and a forecast rainstorm for the Souris and Qu’Appelle watershed this weekend, the option to reopen the controlled release must remain for at least another week. This is required to ensure future river flows, particularly from the storm, do not cause issues with the Portage Diversion structures or the Assiniboine River dikes.
- The mandatory evacuations remain for the 14 homes currently in the area that is affected by water from the controlled release. Property owners in areas of the controlled release zone that have not seen any water, will be allowed to return home but must keep their flood-protection systems in place until further use of the controlled release has been ruled out.
- The mandatory evacuations for residents near the Portage Diversion structures remain in place.
- The controlled release was initially made on May 14 to take pressure off the Portage Diversion and the Assiniboine River dikes. At the time of the controlled spill, inflows at the Portage Reservoir reached 52,300 cubic feet per second (cfs) with the Portage Diversion taking 34,000 cfs and the river downstream of the controlled release was at 18,000 cfs, the maximum flows both could handle at that time. This required at least 300 cfs to be removed through the controlled release.
- While it was open, the release handled approximately 400 cfs in flows per day. The controlled spill affected approximately 3.42 square kilometres of land. Three homes have some water near them and their flood-protection structures have held. As planned, the water has moved east to the Elm River and it will then enter the La Salle River in the coming days.
- 30 -