Here’s why Saanich’s Elk Lake is looking muddy brown and what’s being done about it

If you’ve walked, biked, driven by or paddled near Elk Lake in Saanich lately, you may have noticed the water looking unusually murky or brown—and it’s not just the light playing tricks on you.

Many residents have taken to social media to express concern and curiosity, with several saying they’ve never seen the lake like this before. One person who’s lived across from the lake for over two decades said the current state is unlike anything they’ve witnessed.

The Capital Regional District (CRD) has confirmed to Victoria Buzz that Elk and neighbouring Beaver Lake are currently experiencing a blue-green algae bloom, which has caused both a visual change in the water and a public health advisory that’s been in place since fall 2023.

“There is currently a blue-green algae bloom in Elk and Beaver lakes and the CRD is aware of a change of appearance and colour in the lake over the last number of weeks,” said Glenn Harris, Ph.D., R.P.Bio., Senior Manager of Environmental Protection at the CRD.

“This is likely due to several factors, including the particular strain of algae that is currently in bloom, the population density of the algae in the upper layer of the lake and the duration of the bloom.”

The change in colour can look more intense depending on the time of day and how the sunlight hits the water.

While blue-green algae (cyanobacteria) is naturally occurring and often persistent, it can be dangerous. Such blooms can produce toxins that may cause headaches and abdominal pain in people, and even fatal liver damage in dogs.

In fact, the current bloom forced organizers of the Ironman 70.3 Victoria triathlon to cancel the swimming portion of the race, which was scheduled to take place in Elk Lake last week.

The 1.9-kilometre swim was called off “in the interest of athlete safety,” according to a social media post from event officials. The decision was supported by Triathlon BC, Island Health, and the CRD.

According to Harris, blooms are primarily caused by high levels of nutrients—especially phosphorus—in the water.

Calm conditions, warm temperatures, and sunlight all fuel their growth. While blooms can occur naturally, human activity like agricultural runoff, stormwater runoff, and malfunctioning septic systems significantly increases the chances of one forming.

The CRD conducts visual inspections twice a week at the site of first detection and nearby swimming beaches. If a bloom is confirmed, the CRD works with Island Health to issue an advisory and post warning signage. The advisory is only lifted when the bloom is no longer observed.

Despite the ongoing bloom, there is some good news.

A new oxygenation system installed in Elk Lake in 2023 has already started to show positive results, according to the CRD.

“Recent data shows the Elk Lake oxygenation system has improved deep-water oxygen levels, reduced phosphorus and maintained optimal water temperatures over the last year,” Harris said.

He added that fluctuations in water quality are expected in the short term as the system stabilizes nutrient levels in the lower layers of the lake.

The CRD says it remains committed to the Elk/Beaver Lake watershed management plan, which aims to further reduce external nutrient sources and restore the health of both lakes over time.

In the meantime, locals and visitors are urged to avoid contact with the water, keep pets away, and stay up to date with advisories via crd.bc.ca.