The future of Parksville's water supply and snowpack levels will be impacted by climate change, according to a preliminary report on a Water Use Planning and Management Study.
The city can expect longer, drier summers, according to a presentation by engineers Stephen Bridger and Craig Sutherland of Kerr Wood Leidal, who developed a model that simulates Parksville's water system, reservoir and ground water intake.
Their model lets them look at the status quo, as well as different alternatives in the future, Sutherland said during a recent presentation to council.
They used it to compare a baseline, historical period (1981 to 2010) with what the 2080s are projected to look like, in terms of precipitation and inflows into the Englishman River and Arrowsmith Lake.
"Snowpack is a big driver and that’s going to be reducing in the future,” Sutherland said. “One of the big changes is in June. So, right now the typically the reservoir [releasing] kind of starts early July-ish, well that might be a whole month sooner in the future.”
That change will mean there a longer period of time will be required when the releases from the dam are supporting both the flow needs of the river and the community's water needs, he added.
Parksville can expect increased winter precipitation levels in the future, Sutherland said.
“Keep in mind these are averages and there’s a lot more variability in the future, so the potential for those year over year droughts to happen is gonna increase into the future,” he added.
The Arrowsmith Lake Dam Reservoir, which started operations in 2001, stores approximately 9 million cubic litres of water, under a water licence from the province. When full, it carries enough water to support the current demand for 90 days, Sutherland said.
The dam stores water through the winter and spring, and releases it from roughly mid-July to mid-October to support both environmental flow needs and community use.
Parksville's population is growing at approximately 1.5 per cent a year, Bridger said.
“The growth there flat-lines after 2045 as there is limited development potential,” he added.
The preliminary report included strategies such as increase water meter reading and billing frequency; conversion to “smart” water metres and irrigation upgrades with technology improvements.
Bridger and Sutherland are looking at future water storage options, mostly focused on natural lakes, which include Fish Tail Lake, close to Arrowsmith Dam, Shelton Lake and Healy Lake.
Mayor Doug O'Brien brought up the persistent issue the city is having with clay banks along the Englishman River, which require lots of maintenance by staff at the water treatment plant, as filters become clogged with sludge.
“It’s going to get worse before it gets better, as the water continues with its flood flows and that’s when it starts tearing at that clay bank that is impacting our water treatment,” O'Brien said.
He added he is looking for considerations to create a system that allows a more pure water flow with less silt, such as pulling water out before the flows reach the area with the clay banks.
“The plant itself continues to suffer from this and I know our team does their best but it’s a fact of life,” O'Brien said.
Sutherland said they are in the initial stage of looking at the clay banks issue, and it is something to consider.
The final results of the Water Use Planning and Management Study will be presented to council in the fall.
