It will help with flooding.
It will help with the beloved duck pond not being full of algae and surrounded by duck droppings.
The naturalization of Vernon Creek in Polson Park is a good thing, and necessary, as explained to the Okanagan Basin Water Board (OBWB) staff and directors by City of Vernon lead engineer on the project Mathew Keast, at the board’s meeting Tuesday, Aug. 1, in Coldstream.
With a grant from OBWB toward an estimated $2 million cost of Phase 1, Keast explained the naturalization of the channel includes removal of the existing concrete barriers, concrete duck ponds and lengthening the channel by meandering it along its current course.
Removing the concrete channel and concrete duck ponds will also allow ground water to naturally migrate toward Vernon Creek.
“Studies have shown that these concrete sections act as barriers to groundwater, causing ground water to sit closely to the surface, causing surface ponding in some areas,” said Keast, who showed photographic evidence of such ponding around the Polson Park playground and the spray park, which was demolished in 2021.
Keast said that currently the channelized section acts as a barrier to smaller fish such as kokanee due to the fast-moving water with no areas of rest. The existing channel offers little-to-no spawning habitat but by meandering the channel, adding riffle pools and habitat complexities, he said, the natural spawning habitat can be greatly increased for sockeye salmon, kokanee and rainbow trout.
“The naturalized channel is also designed to accommodate both low flow as well as large flood events that have recently been studied as part of the city’s flood mapping, risk assessment and mitigation work,” said Keast.
OBWB executive director Anna Warwick Sears said the creek was channelized to reduce flooding with straight channels, and now, the naturalization calls for a meandering (windy) stream to help reduce the risk. She asked Keast to explain how bringing in a prior flood plain in a windier creek would reduce flooding compared to a straight channel.
“In the past, channels were designed to what was thought to be the right risk tolerance, like a one-in-100-years event,” said Keast. “As climate change is occurring, we are seeing more and more of these higher flows, these less frequent events happening more often…
“We also have environmental elements. You start channelizing creek channel and there’s the impact that has on the aquatic system, riparian plants, warming up the water temperature, decreasing the dissolved oxygen levels. You start getting algae growth that eats up more oxygen levels and encourages more of the carp and invasive species, and start decreasing the water quality.”
Keast said naturalizing the creek channel is just a “small piece in the grand scheme of things.”
“We’re using the best science we know today,” he said. “I’d love to see this project come through. I think a lot of people of any generation likes a natural habitat. The duck pond is full of algae and surrounded by duck poop. Is that really what you want? I think this is a necessary first step.”
Phase 1 is anticipated to start in the summer of 2024 at Highway 97 along Vernon Creek in Polson Park and continue south toward the current duck pond outlet into the creek channel.