PlaceDossier / BC places / Lakes

BC lake · 61 ha · Victoria watershed

Langford Lake

Its median summer Secchi depth over 2013–2025 was 5.5 m, from 16 readings. Clearer than 61% of the 62 BC lakes with enough recent readings.

The readings

254 summer readings from open water on record from 1973 to 2026, at 4 sampling sites.

Median since 2012Compared with BC lakes
Secchi depth5.5 m
2013–2025, 16 readings		Clearer than 61% of the 62 BC lakes with enough recent readings.
Total phosphorus12 µg/L
2013–2026, 25 readings		Higher than 57% of the 100 BC lakes with enough recent readings.
Chlorophyll a3.5 µg/L
2013–2026, 19 readings		Higher than 71% of the 83 BC lakes with enough recent readings.
Secchi depth how deep a black-and-white disc stays visible: deeper means clearer water
02468 19801990200020102020 1979: median 3.7 m from 2 readings1980: median 1.5 m from 7 readings1981: median 3.0 m from 1 reading1983: median 3.4 m from 1 reading2003: median 4.9 m from 2 readings2004: median 8.5 m from 1 reading2005: median 4.6 m from 8 readings2008: median 4.8 m from 1 reading2009: median 4.5 m from 5 readings2011: median 4.0 m from 5 readings2013: median 6.0 m from 5 readings2015: median 3.4 m from 1 reading2016: median 3.5 m from 1 reading2017: median 4.0 m from 1 reading2018: median 5.5 m from 1 reading2019: median 7.1 m from 1 reading2020: median 4.5 m from 1 reading2021: median 3.2 m from 1 reading2022: median 5.6 m from 1 reading2023: median 5.3 m from 1 reading2024: median 6.1 m from 1 reading2025: median 6.9 m from 1 readingm
Total phosphorus the nutrient that most often feeds algae in BC lakes
1030100 19801990200020102020 1973: median 29 µg/L from 1 reading1980: median 23 µg/L from 16 readings1981: median 26 µg/L from 2 readings1983: median 21 µg/L from 8 readings1984: median 34 µg/L from 10 readings1985: median 34 µg/L from 6 readings1987: median 41 µg/L from 1 reading1989: median 6.0 µg/L from 1 reading2003: median 11 µg/L from 3 readings2004: median 6.0 µg/L from 1 reading2005: median 18 µg/L from 47 readings2006: median 8.0 µg/L from 1 reading2008: median 8.0 µg/L from 1 reading2009: median 8.5 µg/L from 4 readings2011: median 10 µg/L from 3 readings2013: median 11 µg/L from 10 readings2015: median 21 µg/L from 3 readings2016: median 8.3 µg/L from 1 reading2017: median 12 µg/L from 1 reading2018: median 12 µg/L from 1 reading2019: median 8.4 µg/L from 1 reading2020: median 15 µg/L from 1 reading2021: median 16 µg/L from 1 reading2022: median 22 µg/L from 1 reading2023: median 26 µg/L from 1 reading2024: median 11 µg/L from 1 reading2025: median 7.4 µg/L from 1 reading2026: median 163 µg/L from 2 readingsµg/L
Chlorophyll a the green pigment in algae: a direct measure of how much is growing
1310 19801990200020102020 1980: median 6.3 µg/L from 18 readings1981: median 13 µg/L from 2 readings1984: median 7.0 µg/L from 24 readings1985: median 3.1 µg/L from 1 reading2004: median 2.4 µg/L from 1 reading2005: median 3.2 µg/L from 6 readings2009: median 4.9 µg/L from 4 readings2013: median 1.1 µg/L from 5 readings2015: median 9.1 µg/L from 3 readings2016: median 6.5 µg/L from 1 reading2017: median 3.5 µg/L from 1 reading2018: median 3.0 µg/L from 1 reading2019: median 3.4 µg/L from 1 reading2020: median 8.8 µg/L from 1 reading2021: median 7.7 µg/L from 1 reading2022: median 5.4 µg/L from 1 reading2023: median 3.8 µg/L from 1 reading2024: median 1.5 µg/L from 1 reading2025: median 1.5 µg/L from 1 reading2026: median 2.0 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 oligotrophic, phosphorus reads oligotrophic, algae reads mesotrophic. That's common: clarity also depends on silt and colour, not just algae.

IndexClass
From secchi depth (5.5 m, 2013–2025)35oligotrophic
From total phosphorus (12 µg/L, 2013–2026)40oligotrophic
From chlorophyll a (3.5 µg/L, 2013–2026)43mesotrophic

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
2026–163 µg/L (2)2.0 µg/L (1)
20256.9 m (1)7.4 µg/L (1)1.5 µg/L (1)
20246.1 m (1)11 µg/L (1)1.5 µg/L (1)
20235.3 m (1)26 µg/L (1)3.8 µg/L (1)
20225.6 m (1)22 µg/L (1)5.4 µg/L (1)
20213.2 m (1)16 µg/L (1)7.7 µg/L (1)
20204.5 m (1)15 µg/L (1)8.8 µg/L (1)
20197.1 m (1)8.4 µg/L (1)3.4 µg/L (1)
20185.5 m (1)12 µg/L (1)3.0 µg/L (1)
20174.0 m (1)12 µg/L (1)3.5 µg/L (1)
20163.5 m (1)8.3 µg/L (1)6.5 µg/L (1)
20153.4 m (1)21 µg/L (3)9.1 µg/L (3)
20136.0 m (5)11 µg/L (10)1.1 µg/L (5)
20114.0 m (5)10 µg/L (3)–
20094.5 m (5)8.5 µg/L (4)4.9 µg/L (4)
20084.8 m (1)8.0 µg/L (1)–
2006–8.0 µg/L (1)–
20054.6 m (8)18 µg/L (47)3.2 µg/L (6)
20048.5 m (1)6.0 µg/L (1)2.4 µg/L (1)
20034.9 m (2)11 µg/L (3)–
1989–6.0 µg/L (1)–
1987–41 µg/L (1)–
1985–34 µg/L (6)3.1 µg/L (1)
1984–34 µg/L (10)7.0 µg/L (24)
19833.4 m (1)21 µg/L (8)–
19813.0 m (1)26 µg/L (2)13 µg/L (2)
19801.5 m (7)23 µg/L (16)6.3 µg/L (18)
19793.7 m (2)––
1973–29 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

  • 1100944 S.e. Half #3 117 readings
  • 1100953 Centre 112 readings
  • E257395 #10 13 readings
  • E257396 #9 12 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.