PlaceDossier / BC places / Lakes
BC lake · 1 km² · Campbell River watershed
Quinsam Lake
Its median summer Secchi depth over 1984–1985 was 7.0 m, from 4 readings.
The readings
110 summer readings on record from 1984 to 2025, at 3 sampling sites.
| Median, latest 10 sampled years | Compared with BC lakes | |
|---|---|---|
| Secchi depth | 7.0 m 1984–1985, 4 readings | Too few readings (4) to compare with other lakes. |
| Total phosphorus | 4.7 µg/L 2016–2025, 61 readings | Lower than 78% of the 269 BC lakes with at least 5 readings (lower is clearer). |
| Chlorophyll a | 1.0 µg/L 2016–2025, 11 readings | Lower than 75% of the 156 BC lakes with at least 5 readings (lower is clearer). |
Median each year (bigger dot, more readings)Middle half of BC lakesBC median
Source: BC Environmental Monitoring Data System (EnMoDS) results, Environmental Monitoring and Analysis Branch, Province of BC, records to September 19, 2026 (Open Government Licence – British Columbia); lake outlines and names: Freshwater Atlas lakes, Province of BC (Open Government Licence – British Columbia). Summaries by PlaceDossier.
Nutrient level Inferred
Reads as oligotrophic (few nutrients, little algae, usually clear).
| Index | Class | |
|---|---|---|
| From total phosphorus (4.7 µg/L, 2016–2025) | 26 | oligotrophic |
| From chlorophyll a (1.0 µg/L, 2016–2025) | 30 | oligotrophic |
Left out for too few readings (under 5 in the latest 10 sampled years): secchi depth.
Inferred by us, not a provincial classification. Carlson's trophic state index (Carlson 1977, Limnology and Oceanography 22:361) turns each median into a score: 60 − 14.41 ln(Secchi m), 14.42 ln(phosphorus µg/L) + 4.15, 9.81 ln(chlorophyll µg/L) + 30.6. Classes after Carlson and Simpson (1996): under 40 oligotrophic, 40 to 50 mesotrophic, 50 to 70 eutrophic, 70 and over hypereutrophic. The index was built for summer readings from the middle of a lake; ours mix sites and months, so treat the class as a rough guide.
Year by year
| Year | Secchi depth | Total phosphorus | Chlorophyll a |
|---|---|---|---|
| 2025 | – | 4.1 µg/L (17) | 1.1 µg/L (3) |
| 2024 | – | 4.2 µg/L (6) | 1.0 µg/L (1) |
| 2023 | – | 3.0 µg/L (1) | 0.5 µg/L (1) |
| 2021 | – | 3.0 µg/L (1) | 0.9 µg/L (1) |
| 2019 | – | 5.3 µg/L (3) | – |
| 2018 | – | 4.8 µg/L (22) | 1.1 µg/L (2) |
| 2017 | – | 5.0 µg/L (8) | 1.0 µg/L (2) |
| 2016 | – | 8.3 µg/L (3) | 1.0 µg/L (1) |
| 2015 | – | 4.2 µg/L (11) | – |
| 2014 | – | 6.0 µg/L (7) | 1.8 µg/L (2) |
| 2013 | – | 5.6 µg/L (8) | 0.6 µg/L (4) |
| 1985 | 7.0 m (1) | 4.5 µg/L (2) | – |
| 1984 | 7.0 m (3) | – | – |
Median of each year's May to October readings; the number of readings is in brackets.
Source: BC Environmental Monitoring Data System (EnMoDS) results, Environmental Monitoring and Analysis Branch, Province of BC, records to September 19, 2026 (Open Government Licence – British Columbia); lake outlines and names: Freshwater Atlas lakes, Province of BC (Open Government Licence – British Columbia). Summaries by PlaceDossier.
Where it was sampled
- E292118 LOWER QUINSAM LAKE DEEP SITE 1 (PE-7008) 175 readings
- 0900505 QUINSAM LAKE; NEAR SOUTH END 8 readings
- E292119 LOWER QUINSAM LAKE DEEP SITE 2 (PE-7008) 2 readings
Site names and IDs are as recorded in the provincial database; the IDs find each site's full record there.
What this record doesn't cover
Algae bloom reports and invasive mussel checks aren't in this record: the province's Algae Watch map and mussel monitoring aren't published as open data. For swimming, check the regional health authority's beach advisories; for blooms and mussels, ask the province's regional environment office or the local lake association.
Readings are from the province's monitoring database: samples taken by provincial staff, volunteer lake monitors, and companies and local governments that sample under their permits. We keep the ice-free season (May to October), and for phosphorus and chlorophyll only samples from the top 5 m. Each year's figure is the median of that year's readings; the summary is the median of every reading in the lake's latest 10 sampled years. A reading below the lab's detection limit counts at that limit. One site can be a bay rather than the open lake, so a lake's figures can differ from one end to the other.
Water quality changes with the season, the weather and the part of the lake. These are past readings, not a test of the water today: before you buy, ask the local government and the lake association what's known, and test a drinking-water intake yourself.