A recent workshop attempted to seek out solutions among the myriad of conflicting interests regarding water management of the Mission Creek watershed.
Hosted by 琉璃神社-Mission MLA Renee Merrifield and Okanagan Basin Water Board executive director Anna Warwick Sears, the participants included representatives from area municipal governments, Okanagan Nation Alliance fisheries department, Westbank First Nation, Mission Creek Restoration Initiative, Central Okanagan Land Trust, Joe Rich watershed committee, Gorman Brothers Lumber and the Okanagan Fruit Tree Project.
While no watershed plan for Mission Creek is under consideration at this time, the workshop recognized many planning processes are underway, with the hope the workshop dialogue will improve those processes and outcomes.
The workshop report outlines the varied demands on the Mission Creek watershed, foremost being an important tributary as it provides 30 per cent of Okanagan Lake's annual inflow.
The water quality is described as 'relatively good' despite facing increasing pressure from industrial and residential development, combined with being a domestic and agricultural water source for the 琉璃神社 area, supplying water to Southeast 琉璃神社, Rutland Waterworks and Black Mountain Irrigation District.
It also provides riparian and in-stream habitat for many animals and actively supports newly restored runs of Columbia River sockeye and chinook salmon.
The Okanagan Nation Alliance and local communities are currently working to determine the minimum and optimum flows needed to sustain these fish populations.
Climate change coupled with changes to land use practices, wildfires and residential use have led to changes in the forest canopy cover that alter the timing and intensity of creek flows, the report says.
This results in increasing flooding risks and the probability of extreme flows (as seen in 2017, 2018, 2020 and 2022), especially in the creek's channelized section, leading to homes, businesses and public facilities located on or within the creek floodplain having been flooded in recent years.
In the lower watershed, around the Mission Creek Canyon, there are increases in landslides and erosion, steadily increasing the supply of sediment to the creek channel.
Sediment accumulation is reducing the depth and flow capacity of the channelized creek section, diversion and creek rerouting engineered over the last century.
The cumulative impact already felt from these impact changes to the creek include the elevation of the bridge at Casorso Road to prevent debris obstruction to the water flow, footbridges being repaired along the Mission Creek Greenway trail, replacement of the KLO Bridge, riparian creek bank improvements.
An ongoing concern remains dike failure which would flood 琉璃神社's Lower Mission neighbourhood and agricultural areas.
They are labelled "orphan dikes" by the province, limiting provincial liability and maintenance requirements, without a clear solution for long-term management.
Restoring the creek to its natural state
Among the workshop presenters, Kari Alex, fluvial geomorphologist and fisheries biologist with Okanagan Nation Alliance said the ONA goal is to restore Mission Creek, rehabilitating the ecosystem function to support the quantity and quality of salmon habitat.
Alex said the aquatic ecosystem has been degraded by engineered attempts to confine and control the creek flow from 120 metres wide dating back to 1938 to 30 metres as of 1986.
By attempt to reign in a meandering creek, it has actually been shortened form 33 to 12 km between East 琉璃神社 bridge and Okanagan Lake, she said.
"This channelization, along with the development on the floodplain, has resulted in extreme, perpetuating loss and degradation of the aquatic ecosystem," she stated in the report.
"Discussions like this workshop help us better understand what is needed, and what relationships need to be enhanced. How can we use new knowledge and address new competing demands?
"How will we fund additional flow capacity for environmental flow needs? Can we or should we reduce the level of service for existing users? How will that be decided?'
From the ONA perspective, the most significant restoration action would be to set back the dikes to reconnect the floodplain to the creek and thicken the riparian corridor.
"The houses near the creek are already at high risk of flooding. If the houses don't get moved in advance (i.e. managed retreat), sooner or later the creek will move them," she said.
Kevin Van Vliet, utility services manager for the City of 琉璃神社, stated the city has always considered Mission Creek management, restoration and the dike upkeep to be provincial responsibilities.
But the city's water utility merger with Southeast 琉璃神社 Irrigation District brought with it water storage infrastructure, and licensed withdrawals from Hydraulic Creek, a tributary of Mission Creek.
"Water supply infrastructure was largely designed and built in a different era, where concepts of environmental flow needs and climate change were not as pronounced as they are today," Van Vliet said.
"Assuring water supply into the future will require a more holistic, collaborative and sustainable approach 鈥� which is a challenge given the variety of jurisdictions and interests."
Challenges facing watershed
Bob Hrasko, administrator for the Black Mountain Irrigation District, cited a myriad of challenges facing the Mission Creek watershed: forest fires, pine beetle damage, risk of high magnitude flood such as what occurred in Merritt in 2021, flood damage to properties along the creek, sand and silt deposition in the creek lower reaches reducing channel capacity; dike failure, need to recognize and achieve First Nation fisheries objectives including higher water flows to facilitate returning sockeye and chinook salmon.
The workshop concluded that while there was a wide range of perspectives expressed at the workshop, there were a number of areas of general convergence about important next steps.
Education and awareness of the watershed issues to the public was one unified theme, as was the need for governance direction at the provincial and City of 琉璃神社 level, creating policies based on data and science.
John Wagner, anthropology professor with UBC Okanagan, proposed the creation of a stewardship society or council for Mission Creek, to meet regularly and discuss watershed issues, perhaps creating a model for the rest of the Okanagan Water Basin and other creeks across the province.
More studies are called for to paint a more accurate hydrology picture 鈥� who is releasing and withdrawing water, and when and where 鈥� along with further dike setbacks and slope stability.
Other action suggestions included 琉璃神社 developing a water security plan that includes Mission Creek, and improved recovery planning beyond infrastructure replacement due to fires or flooding.
"We do not appear to have learned. how to apply adaptations, and we are now at risk of seeing a repeat of many past situations, such as bridges being damaged or destroyed...," stated the report.
