PlaceDossier / BC places / Lakes

BC lake · 4 km² · Middle Fraser watershed

Chimney Lake

Its median summer Secchi depth over 2017–2025 was 2.9 m, from 15 readings. Murkier than 75% of the 62 BC lakes with enough recent readings.

The readings

185 summer readings from open water on record from 1979 to 2025, at 3 sampling sites.

Median since 2012Compared with BC lakes
Secchi depth2.9 m
2017–2025, 15 readings		Murkier than 75% of the 62 BC lakes with enough recent readings.
Total phosphorus11 µg/L
2012–2025, 34 readings		Higher than 54% of the 100 BC lakes with enough recent readings.
Chlorophyll a2.2 µg/L
2012–2025, 20 readings		Higher than 55% of the 83 BC lakes with enough recent readings.
Secchi depth how deep a black-and-white disc stays visible: deeper means clearer water
0246 19801990200020102020 1979: median 3.3 m from 23 readings1984: median 5.0 m from 1 reading2017: median 2.9 m from 3 readings2018: median 3.4 m from 2 readings2019: median 3.9 m from 1 reading2020: median 3.7 m from 1 reading2021: median 3.0 m from 2 readings2022: median 3.2 m from 2 readings2023: median 2.8 m from 2 readings2024: median 2.0 m from 1 reading2025: median 1.9 m from 1 readingm
Total phosphorus the nutrient that most often feeds algae in BC lakes
1030 19801990200020102020 1979: median 13 µg/L from 28 readings1984: median 22 µg/L from 2 readings1994: median 22 µg/L from 3 readings1995: median 8.0 µg/L from 1 reading1996: median 18 µg/L from 1 reading1997: median 25 µg/L from 11 readings2000: median 29 µg/L from 4 readings2001: median 16 µg/L from 4 readings2002: median 8.0 µg/L from 4 readings2011: median 6.5 µg/L from 6 readings2012: median 11 µg/L from 7 readings2013: median 9.2 µg/L from 8 readings2015: median 6.9 µg/L from 3 readings2016: median 9.4 µg/L from 1 reading2017: median 17 µg/L from 3 readings2018: median 11 µg/L from 2 readings2019: median 11 µg/L from 1 reading2020: median 11 µg/L from 1 reading2021: median 19 µg/L from 2 readings2022: median 12 µg/L from 2 readings2023: median 17 µg/L from 2 readings2024: median 13 µg/L from 1 reading2025: median 7.1 µg/L from 1 readingµg/L
Chlorophyll a the green pigment in algae: a direct measure of how much is growing
13 19801990200020102020 1979: median 2.0 µg/L from 25 readings1996: median 5.9 µg/L from 1 reading2011: median 1.8 µg/L from 2 readings2012: median 1.9 µg/L from 2 readings2013: median 1.9 µg/L from 2 readings2015: median 2.6 µg/L from 1 reading2016: median 2.2 µg/L from 1 reading2017: median 2.9 µg/L from 2 readings2018: median 2.4 µg/L from 2 readings2019: median 2.4 µg/L from 1 reading2020: median 2.1 µg/L from 1 reading2021: median 8.0 µg/L from 2 readings2022: median 2.8 µg/L from 2 readings2023: median 2.8 µg/L from 2 readings2024: median 1.9 µg/L from 1 reading2025: median 1.5 µg/L from 1 readingµg/L

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: clarity reads mesotrophic, phosphorus reads oligotrophic, algae reads oligotrophic. That's common: clarity also depends on silt and colour, not just algae.

IndexClass
From secchi depth (2.9 m, 2017–2025)45mesotrophic
From total phosphorus (11 µg/L, 2012–2025)38oligotrophic
From chlorophyll a (2.2 µg/L, 2012–2025)38oligotrophic

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

YearSecchi depthTotal phosphorusChlorophyll a
20251.9 m (1)7.1 µg/L (1)1.5 µg/L (1)
20242.0 m (1)13 µg/L (1)1.9 µg/L (1)
20232.8 m (2)17 µg/L (2)2.8 µg/L (2)
20223.2 m (2)12 µg/L (2)2.8 µg/L (2)
20213.0 m (2)19 µg/L (2)8.0 µg/L (2)
20203.7 m (1)11 µg/L (1)2.1 µg/L (1)
20193.9 m (1)11 µg/L (1)2.4 µg/L (1)
20183.4 m (2)11 µg/L (2)2.4 µg/L (2)
20172.9 m (3)17 µg/L (3)2.9 µg/L (2)
2016–9.4 µg/L (1)2.2 µg/L (1)
2015–6.9 µg/L (3)2.6 µg/L (1)
2013–9.2 µg/L (8)1.9 µg/L (2)
2012–11 µg/L (7)1.9 µg/L (2)
2011–6.5 µg/L (6)1.8 µg/L (2)
2002–8.0 µg/L (4)–
2001–16 µg/L (4)–
2000–29 µg/L (4)–
1997–25 µg/L (11)–
1996–18 µg/L (1)5.9 µg/L (1)
1995–8.0 µg/L (1)–
1994–22 µg/L (3)–
19845.0 m (1)22 µg/L (2)–
19793.3 m (23)13 µg/L (28)2.0 µg/L (25)

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

  • 0603097 . at Nw end 98 readings
  • 0603098 Near centre 56 readings
  • 0603104 . at Se end 31 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.