City of Nelson’s Water Treatment System
By Scott Eagleson
From Mountains to Lake: Harnessing Creeks in the Kootenay’s
The EOCP Board of Directors took the opportunity to inspect a few of the treatment facilities that serve the Kootenay’s. In May 2024, the board convened in Nelson.
And, like the quirky towns themselves, the utilities that serve them are just as unique.
Incorporated in 1897, this already booming mining town saw exponential growth at the turn of the century, and the water utility had to keep up. By the mid 1920’s, the small open-air drinking water reservoirs above town couldn’t meet the demand of a growing town that was soon building around them. Soon after, work started on a system that would be the foundation of Nelson’s water system for the next 100 years. The engineers at this time bet their hand on a strong creek that flowed high above town called Five Mile Creek, named so after the ‘mile markers’ along the shore of Kootenay Lake that provided the CPR paddle wheelers with their bearings as they approached Nelson. Over the decades, other water sources were brought online to share the load: Selous Creek and Fell and Anderson Creeks which conveniently flow through the town.
Tapping into the mosaic of watersheds that all share a common regional location in the mountains above Nelson before descending on opposing aspects has become essential to Nelson’s water security. While other Kootenay municipalities had to reach further and further out to secure water, Nelsonites only had to look up. The central Kootenay’s are characterized by steep and fast snow-fed water courses, which rely on healthy amounts of annual snowfall and an evenly-paced spring freshet. But that also makes storage expensive, difficult, and has had an indelible impact on the shapes of Nelson’s system: the watersheds ARE the storage.
Nelson’s operating water system is still very much attached to the ingenuity and determination of the town’s forebears in the 1920s. Five Mile Creek routinely meets 90% of Nelson’s demand for water, delivering it from the intake (located seven kilometers and 550 meters above town) via the 12 inch diameter 1927 French-steel pipeline to a poured-cement reservoir of the same vintage. The reservoir also operates as an effective settling pond, giving the cold mountain water time to drop its turbidity before entering the plant.
While mountain creeks can be hard to tame, they do at least guarantee one critical attribute: little if no one else has handled the water that has been collected. Nelson relied on the ecological service that watersheds quietly provide through simply holding and mitigating total suspended solids so effectively that for decades water was captured, chlorinated and fed directly into the distribution system. Climate variability, its impact on snowpack predictability, and the increasing expectations of regulators eventually led to the decision to construct the Anderson Creek Booster Station. One of the biggest assets that Nelson’s Water Utility has commissioned in years, this facility hosts twin 200 hp centrifugal pumps that lift raw water from Anderson Creek nearly 100 meters in elevation to the Mountain Station Water Treatment Facility, all part of a multi-year capital plan to consolidate Nelson’s raw water feeds at a single location for treatment.
This key attribute helps keep Nelson’s treatment simple. Water enters the plant through stainless steel strainers and through one of two flow-paced 24-inch diameter 5×10 kW ultraviolet light disinfection systems. Because ultraviolet light transmittance is key to an effective UV system, starting with clear water is essential, and mountain watersheds are ideal for this, as the water (locked as snow or fast-moving water) does not linger long enough to pick up the tannins that can hobble the potency of a UV system.
An on-site sodium hypochlorite generation system provides chlorine treatment, and after residency time in the contact tank, treated water begins its steep descent into Nelson’s distribution system. Water pressure management becomes a focus here. Controlling the descent of water through the town is a network of pressure-reducing valves that divide the town into four cascading tiers. These valves control system pressure as water moves down through town, serving our customers along the way until the last drinking water fountain in Lakeside Park.