PlaceDossier / BC places / Lakes
BC lake · 423 km² · Kootenay Lake watershed
Kootenay Lake
Its median summer total phosphorus over 2012–2026 was 5.0 µg/L, from 1,161 readings. Lower than 69% of the 100 BC lakes with enough recent readings (lower is clearer).
The readings
4,037 summer readings from open water on record from 1970 to 2026, at 17 sampling sites.
| Median since 2012 | Compared with BC lakes | |
|---|---|---|
| Secchi depth | Too few readings to judge last sampled in 1984, before 2012 | Too few readings to compare (last sampled in 1984, before 2012). |
| Total phosphorus | 5.0 µg/L 2012–2026, 1,161 readings | Lower than 69% of the 100 BC lakes with enough recent readings (lower is clearer). |
| Chlorophyll a | 2.7 µg/L 2019–2026, 335 readings | Higher than 62% of the 83 BC lakes with enough recent 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
The measures disagree: phosphorus reads oligotrophic, algae reads mesotrophic. That's common: clarity also depends on silt and colour, not just algae.
| Index | Class | |
|---|---|---|
| From total phosphorus (5.0 µg/L, 2012–2026) | 27 | oligotrophic |
| From chlorophyll a (2.7 µg/L, 2019–2026) | 40 | mesotrophic |
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 (last sampled in 1984, before 2012).
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 |
|---|---|---|---|
| 2026 | – | 5.0 µg/L (25) | 2.0 µg/L (11) |
| 2025 | – | 5.8 µg/L (53) | 2.5 µg/L (45) |
| 2024 | – | 5.7 µg/L (52) | 2.3 µg/L (46) |
| 2023 | – | 5.4 µg/L (53) | 2.1 µg/L (46) |
| 2022 | – | 5.4 µg/L (86) | 3.2 µg/L (66) |
| 2021 | – | 4.9 µg/L (55) | 3.1 µg/L (46) |
| 2020 | – | 5.6 µg/L (54) | 3.3 µg/L (34) |
| 2019 | – | 5.4 µg/L (92) | 2.5 µg/L (41) |
| 2018 | – | 6.3 µg/L (103) | – |
| 2017 | – | 4.8 µg/L (94) | – |
| 2016 | – | 3.8 µg/L (100) | – |
| 2015 | – | 3.6 µg/L (104) | – |
| 2014 | – | 4.3 µg/L (98) | – |
| 2013 | – | 4.4 µg/L (91) | – |
| 2012 | – | 4.9 µg/L (101) | – |
| 2011 | – | 4.0 µg/L (101) | – |
| 2010 | – | 3.0 µg/L (69) | – |
| 2009 | – | 3.0 µg/L (78) | – |
| 2008 | – | 4.0 µg/L (74) | – |
| 2007 | – | 5.0 µg/L (90) | 2.0 µg/L (73) |
| 2006 | – | 3.5 µg/L (68) | 2.9 µg/L (72) |
| 2005 | – | 3.0 µg/L (66) | 1.9 µg/L (69) |
| 2004 | – | 4.0 µg/L (123) | 2.7 µg/L (108) |
| 2003 | – | 4.0 µg/L (88) | 2.2 µg/L (78) |
| 2002 | – | 7.5 µg/L (24) | 3.6 µg/L (16) |
| 2001 | – | 4.5 µg/L (30) | 1.6 µg/L (30) |
| 2000 | – | 8.0 µg/L (42) | 1.1 µg/L (36) |
| 1999 | – | 6.0 µg/L (20) | 1.1 µg/L (20) |
| 1998 | – | 6.5 µg/L (20) | 1.6 µg/L (20) |
| 1997 | – | 12 µg/L (14) | 2.7 µg/L (16) |
| 1996 | – | – | 3.0 µg/L (90) |
| 1995 | – | 4.0 µg/L (91) | 2.3 µg/L (91) |
| 1994 | – | 3.0 µg/L (91) | 2.3 µg/L (91) |
| 1993 | – | 4.0 µg/L (84) | 3.2 µg/L (83) |
| 1992 | – | 4.0 µg/L (90) | 2.7 µg/L (83) |
| 1991 | – | 3.0 µg/L (2) | 2.2 µg/L (2) |
| 1990 | – | 6.5 µg/L (2) | 2.5 µg/L (2) |
| 1988 | – | 4.0 µg/L (5) | – |
| 1987 | – | 5.0 µg/L (7) | – |
| 1986 | – | 5.0 µg/L (5) | – |
| 1985 | – | 7.0 µg/L (10) | – |
| 1984 | 5.5 m (5) | 8.0 µg/L (5) | 2.5 µg/L (10) |
| 1983 | 7.7 m (4) | 7.0 µg/L (6) | 2.6 µg/L (8) |
| 1982 | 5.5 m (4) | 9.0 µg/L (6) | 3.7 µg/L (10) |
| 1981 | 6.0 m (5) | 8.5 µg/L (8) | 2.2 µg/L (9) |
| 1980 | 6.6 m (6) | 10 µg/L (7) | 2.6 µg/L (12) |
| 1979 | 5.7 m (6) | 9.0 µg/L (6) | 2.4 µg/L (11) |
| 1978 | 5.8 m (3) | 6.0 µg/L (4) | 2.4 µg/L (7) |
| 1977 | 7.0 m (6) | 8.0 µg/L (6) | 2.7 µg/L (11) |
| 1976 | 6.1 m (5) | 8.5 µg/L (6) | 3.7 µg/L (12) |
| 1975 | 7.0 m (8) | 9.0 µg/L (14) | 2.3 µg/L (6) |
| 1974 | 5.5 m (9) | 12 µg/L (6) | – |
| 1973 | 3.7 m (5) | 11 µg/L (9) | – |
| 1972 | 2.0 m (4) | 25 µg/L (6) | – |
| 1971 | 2.1 m (4) | 22 µg/L (4) | – |
| 1970 | 5.8 m (3) | 30 µg/L (1) | – |
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
- E216950 At Kembell Creek (Klf 2) 819 readings
- E216954 At Rhinoceros Point (Klf 6) 794 readings
- E216952 At Hendryx Creek (Klf 4) 452 readings
- E218832 At Redman Point, KLF7 419 readings
- E216953 South of Crawford bay at Wilson Creek (Klf 5) 360 readings
- E216951 At Bjerkeness Creek (Klf 3) 346 readings
- E216949 At Johnson's Landing (Klf 1) 338 readings
- 0200034 At Cape Horn 303 readings
- E252949 West arm (KLF8) 178 readings
- E206384 At Bernard Creek 5 readings
- E256502 North of Nelson at lower Six Mile, site 2 5 readings
- E256506 North of Nelson at Shannon Point, site 3 5 readings
- E256509 North of Nelson at One Mile, site 1 5 readings
- E256512 Near Nelson at Johnstone Road, site 2 5 readings
- E228122 Middle of Kaslo bay 1 reading
- E228124 500 Meters D/s Kaslo River 1 reading
- E256513 At Johnstone Road, site 3 (Nelson) 1 reading
Left out: 11 readings at 3 sites whose names put them away from the open lake
- E206613 North of Ainsworth outfall 5 readings; an outfall or discharge
- E206614 South of Ainsworth outfall 5 readings; an outfall or discharge
- E228123 D/s Kaslo Stp 1 reading; an outfall or discharge
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.