Prospect Lake Health Is in Decline
Understand what’s changing in the lake, what monitoring is showing, and why it matters.
View infographicProspect Lake is a shared Saanich community and recreational asset. PLPS works to protect its long-term ecological and recreational health through science, stewardship, monitoring and community engagement.
The most immediate management challenge is Eurasian watermilfoil (EWM), a highly invasive aquatic plant that outcompetes native vegetation, interferes with swimming and boating, alters habitat and becomes increasingly difficult and expensive to manage as it spreads.
EWM was first identified in Prospect Lake in 2018. It has since spread rapidly, and 2026 drone work shows that it covers at least half of the shoreline and is also present in central areas of the lake.
Levels of dissolved oxygen and phosphorus, cyanobacteria that can produce toxins, and other indicators of lake health are related but distinct environmental management issues. PLPS is monitoring these conditions separately so that each can be assessed and managed according to its own evidence.
PLPS is in Year 3 of EWM mapping, water-quality monitoring, laboratory testing, scientific review and advice, community engagement and lake-management planning. Residents have contributed substantial professional expertise, volunteer time and funding to support this work.
In 2025, PLPS completed a drone survey to document aquatic vegetation from the air. In August 2026, that work was expanded through a 148-point lake-wide survey of aquatic plants, combining drone orthographic mapping with field rake sampling and providing a stronger baseline for future monitoring and management.
Over the past 18 months, PLPS has held seven public community meetings to discuss lake conditions, scientific findings and possible management approaches, with 50–125 participants attending individual meetings.
PLPS is pursuing the provincial regulatory process required for EWM management while developing a 25-year adaptive-management framework based on continued monitoring, defined thresholds, periodic reassessment and evidence-based decisions as conditions change.
That community foundation creates an opportunity for long-term cooperation among the community, Saanich, the Province, First Nations and other partners. Protecting a shared public and community asset over the long term will require durable partnerships, additional resources and continuity.
These short PLPS information sheets provide additional background. Select any preview to open the full PDF.
Understand what’s changing in the lake, what monitoring is showing, and why it matters.
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How this invasive aquatic plant is affecting the lake, and why PLPS is pursuing a long-term management approach.
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PLPS’s history, and some of the work the community has undertaken to protect Prospect Lake since 2008.
View infographicPLPS is a volunteer-led, registered British Columbia not-for-profit society.
Email:
plps@prospectlake.net
Mailing address:
Prospect Lake Preservation Society
PO Box 49008 RPO Royal Oak
Victoria, BC V8Z 0G2
Community contributions support lake-health monitoring, scientific and technical work, regulatory processes, and long-term protection and recovery of Prospect Lake.
Direct contributions:
E-transfer to donation@prospectlake.net
Donations requiring a tax receipt:
Tax-receiptable donations may be made through the Saanich Legacy Foundation for Prospect Lake Preservation Society (PLPS). For the current tax-receiptable donation link, please email plps@prospectlake.net.
Prospect Lake Preservation Society respectfully acknowledges that Prospect Lake is on the unceded lands of the W̱SÁNEĆ First Nations and the Lək̓ʷəŋən People, known today as the Esquimalt and Songhees Nations. We recognize their enduring relationships with these lands and waters and the importance of Indigenous knowledge and stewardship in understanding and caring for them. As PLPS works to better understand and protect Prospect Lake, we are committed to approaching future engagement with respect, listening and a willingness to learn.
The SENĆOŦEN name for Prospect Lake is XOĆEs TŦE W̱SÁSENEĆ, meaning “lake of the little emerging mountain.”