PlaceDossier / BC places / Lakes
BC lake · 9 km² · Nicola River watershed
Pennask Lake
Its median summer Secchi depth over 2017–2026 was 2.6 m, from 18 readings. Murkier than 84% of the 122 BC lakes with at least 5 readings.
The readings
88 summer readings on record from 2001 to 2026, at 3 sampling sites.
| Median, latest 10 sampled years | Compared with BC lakes | |
|---|---|---|
| Secchi depth | 2.6 m 2017–2026, 18 readings | Murkier than 84% of the 122 BC lakes with at least 5 readings. |
| Total phosphorus | 16 µg/L 2017–2026, 22 readings | Higher than 64% of the 269 BC lakes with at least 5 readings. |
| Chlorophyll a | 6.7 µg/L 2017–2026, 19 readings | Higher than 84% of the 156 BC lakes with at least 5 readings. |
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 mesotrophic (moderate nutrients and algae).
| Index | Class | |
|---|---|---|
| From secchi depth (2.6 m, 2017–2026) | 47 | mesotrophic |
| From total phosphorus (16 µg/L, 2017–2026) | 44 | mesotrophic |
| From chlorophyll a (6.7 µg/L, 2017–2026) | 49 | mesotrophic |
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 |
|---|---|---|---|
| 2026 | 2.3 m (1) | 18 µg/L (2) | 9.4 µg/L (2) |
| 2025 | 2.7 m (2) | 19 µg/L (2) | 8.4 µg/L (2) |
| 2024 | 3.2 m (2) | 17 µg/L (2) | 1.9 µg/L (2) |
| 2023 | 2.9 m (2) | 29 µg/L (2) | 5.4 µg/L (2) |
| 2022 | 3.6 m (2) | 26 µg/L (2) | 4.6 µg/L (2) |
| 2021 | 2.3 m (2) | 13 µg/L (4) | 8.3 µg/L (2) |
| 2020 | 2.3 m (1) | 9.1 µg/L (2) | 13 µg/L (1) |
| 2019 | 3.6 m (2) | 14 µg/L (2) | 5.3 µg/L (2) |
| 2018 | 2.2 m (2) | 29 µg/L (2) | 11 µg/L (2) |
| 2017 | 2.1 m (2) | 23 µg/L (2) | 11 µg/L (2) |
| 2016 | 3.1 m (2) | 13 µg/L (3) | 4.5 µg/L (2) |
| 2015 | 2.5 m (1) | 13 µg/L (3) | 4.7 µg/L (2) |
| 2014 | – | 17 µg/L (1) | – |
| 2010 | – | 8.0 µg/L (1) | – |
| 2008 | – | 23 µg/L (2) | – |
| 2006 | – | 53 µg/L (2) | – |
| 2004 | – | 56 µg/L (2) | – |
| 2003 | – | 54 µg/L (2) | – |
| 2001 | – | 65 µg/L (6) | – |
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
- 0603071 PENNASK LK NEAR CENTER 72 readings
- E252114 PENNASK LAKE 14 readings
- E244094 PENNASK LK NEAR INLET 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.