PlaceDossier / BC places / Lakes
BC lake · 2 km² · Thompson River watershed
Tunkwa Lake
Its median summer total phosphorus over 2014–2019 was 36 µg/L, from 35 readings. Higher than 91% of the 100 BC lakes with enough recent readings.
The readings
84 summer readings from open water on record from 1992 to 2019, at 2 sampling sites.
| Median since 2012 | Compared with BC lakes | |
|---|---|---|
| Secchi depth | Too few readings to judge 17 readings since 2012, in 2 years | Too few readings to compare (17 readings since 2012, in 2 years). |
| Total phosphorus | 36 µg/L 2014–2019, 35 readings | Higher than 91% of the 100 BC lakes with enough recent readings. |
| Chlorophyll a | Too few readings to judge 17 readings since 2012, in 2 years | Too few readings to compare (17 readings since 2012, in 2 years). |
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 eutrophic (rich in nutrients, with more algae and weed growth).
| Index | Class | |
|---|---|---|
| From total phosphorus (36 µg/L, 2014–2019) | 56 | eutrophic |
Left out for too few recent readings (we need at least 10 summer readings from open water, spread over at least 3 different years, since 2012): secchi depth (17 readings since 2012, in 2 years); chlorophyll a (17 readings since 2012, in 2 years).
Inferred by us, not a provincial classification. 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.
How we worked this out
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.
Year by year
| Year | Secchi depth | Total phosphorus | Chlorophyll a |
|---|---|---|---|
| 2019 | 3.3 m (9) | 28 µg/L (18) | 4.3 µg/L (9) |
| 2018 | 2.5 m (8) | 41 µg/L (15) | 11 µg/L (8) |
| 2015 | – | 24 µg/L (1) | – |
| 2014 | – | 39 µg/L (1) | – |
| 2008 | – | 58 µg/L (2) | – |
| 2006 | – | 57 µg/L (2) | – |
| 2004 | – | 68 µg/L (2) | – |
| 2003 | – | 62 µg/L (2) | – |
| 1996 | – | 26 µg/L (1) | – |
| 1995 | – | 126 µg/L (1) | 177 µg/L (1) |
| 1993 | – | 26 µg/L (2) | – |
| 1992 | – | 32 µg/L (2) | – |
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
- E252112 Main site 77 readings
- 0603069 At centre 7 readings
Site names are tidied from the provincial records; 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. We leave out sites whose names put them at a water intake, a sewage or industrial outfall, a mine or a permit holder's works, or on the shore (a beach, dock or boat launch): water there can differ a lot from the open lake. Each year's figure is the median of that year's readings. We give a lake a summary, a comparison with other lakes and a nutrient level only when it has at least 10 summer readings from open water, spread over at least 3 different years, since 2012; the summary is the median of those readings. With fewer, or only older ones, we show the readings and say there are too few to judge the lake. 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.