A water quality snapshot of Grafton Lake, Bowen Island
Bibliographic record
Abstract
Water is essential for life, and steps are needed to understand, protect and restore its health throughout British Columbia (BC). The Raincoast Healthy Waters program (Raincoast Conservation Foundation) was launched in 2023 and conducts community-oriented water pollution monitoring in partnering BC watersheds. The Healthy Waters team conducted a one-time visit to sample water at the outflow from Grafton Lake on Bowen Island (Figure 1), BC, on October 8, 2024. This ‘snapshot’ assessment was used to compare against the more comprehensive sampling done in other watersheds, and contributes to an understanding of threats to water quality, monitoring options and action priorities for the community. The composite sample was analysed for coliform, nutrients (6), physical parameters, metals (37), pesticides (62), polycyclic aromatic hydrocarbons (PAHs; 76), pharmaceuticals and personal care products (PPCPs; 141), polychlorinated biphenyls (PCBs; 209), alkylphenol ethoxylates (APEs; 4), bisphenols (BPs; 6), per- and poly-fluoroalkyl substances (PFAS; 40), and sucralose. Results for the tire chemical breakdown product 6PPD-Quinone are pending. Results from Grafton Lake were compared to samples collected from source water (i.e. above built-up environments and generally an upstream reference sample for the watershed) in 12 other BC watersheds. Results were also compared to pertinent Drinking Water Quality Guidelines from Health Canada (n=35), Environmental Quality Guidelines from BC (n=56), the Canadian Council of Ministers of the Environment (n=43), and Federal Environmental Quality Guidelines (n=7). We detected 125 contaminants out of 587 measured in Grafton Lake, excluding nutrients, fecal coliform and physical parameters. Grafton Lake ranked 8th most contaminated overall out of 21 source water samples from 12 watersheds in BC. This ranking was driven by relatively high concentrations of the human waste tracer sucralose (ranked 1 of 21), PCBs (3 of 21), PAHs (3 of 21), PPCPs (6 of 21), and PFAS (6 of 21). There were no exceedances of available Drinking Water Guidelines (for which we have Guidelines for just 6% of our analytes) or Environmental Quality Guidelines (for which we have Guidelines for just 10% of our analytes). This lake is an important source of drinking water for Bowen island, as well as habitat for coho salmon and cutthroat trout. A combination of human waste and atmospheric deposition of pollutants into a relatively shallow lake (average depth 8.8 m; maximum depth 16 m; perimeter 14.7 km2) appear to be driving water quality profiles in Grafton Lake. These initial findings point to the value of monitoring and enhanced protection measures for this important water body on Bowen Island, which serves people, fish and wildlife.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".