PlaceDossier / BC places / Lakes

BC lake · 350 km² · Okanagan River watershed

Okanagan Lake

Its median summer Secchi depth over 2016–2025 was 5.5 m, from 194 readings. Clearer than 57% of the 122 BC lakes with at least 5 readings.

The readings

3,252 summer readings on record from 1973 to 2026, at 55 sampling sites.

Median, latest 10 sampled yearsCompared with BC lakes
Secchi depth5.5 m
2016–2025, 194 readings		Clearer than 57% of the 122 BC lakes with at least 5 readings.
Total phosphorus6.1 µg/L
2017–2026, 198 readings		Lower than 69% of the 269 BC lakes with at least 5 readings (lower is clearer).
Chlorophyll a2.0 µg/L
2017–2026, 197 readings		Higher than 52% of the 156 BC lakes with at least 5 readings.
Secchi depth how deep a black-and-white disc stays visible: deeper means clearer water
0510 19801990200020102020 1973: median 6.4 m from 5 readings1974: median 5.8 m from 3 readings1975: median 7.0 m from 17 readings1976: median 5.5 m from 17 readings1977: median 8.3 m from 10 readings1978: median 6.1 m from 14 readings1979: median 9.7 m from 13 readings1980: median 9.0 m from 13 readings1981: median 8.8 m from 9 readings1982: median 7.6 m from 14 readings1983: median 6.1 m from 17 readings1984: median 7.5 m from 24 readings1985: median 6.2 m from 21 readings1986: median 8.5 m from 3 readings1987: median 12 m from 8 readings1988: median 11.3 m from 11 readings1989: median 12.5 m from 2 readings1990: median 9.4 m from 14 readings1991: median 10.8 m from 12 readings1992: median 11.1 m from 11 readings1994: median 10.3 m from 16 readings1995: median 10.3 m from 6 readings1997: median 7.5 m from 2 readings1999: median 7.1 m from 34 readings2000: median 6.2 m from 40 readings2001: median 7.2 m from 40 readings2002: median 6.5 m from 35 readings2003: median 6.8 m from 47 readings2004: median 6.5 m from 31 readings2007: median 9.0 m from 7 readings2009: median 9.4 m from 4 readings2010: median 6.3 m from 16 readings2011: median 3.9 m from 17 readings2012: median 5.9 m from 23 readings2013: median 5.9 m from 20 readings2014: median 8.1 m from 15 readings2015: median 7.6 m from 20 readings2016: median 5.9 m from 20 readings2017: median 5.6 m from 20 readings2018: median 4.2 m from 18 readings2019: median 5.9 m from 20 readings2020: median 5.5 m from 20 readings2021: median 5.5 m from 17 readings2022: median 5.7 m from 20 readings2023: median 4.4 m from 20 readings2024: median 6.5 m from 20 readings2025: median 5.9 m from 19 readingsm
Total phosphorus the nutrient that most often feeds algae in BC lakes
310 19801990200020102020 1973: median 6.0 µg/L from 5 readings1974: median 8.5 µg/L from 4 readings1975: median 8.0 µg/L from 15 readings1976: median 10 µg/L from 33 readings1977: median 7.0 µg/L from 18 readings1978: median 8.0 µg/L from 26 readings1979: median 7.0 µg/L from 16 readings1980: median 8.0 µg/L from 13 readings1981: median 10 µg/L from 13 readings1982: median 11 µg/L from 13 readings1983: median 12 µg/L from 18 readings1984: median 13 µg/L from 26 readings1985: median 9.0 µg/L from 24 readings1986: median 6.0 µg/L from 16 readings1987: median 8.0 µg/L from 15 readings1988: median 4.5 µg/L from 16 readings1989: median 4.0 µg/L from 15 readings1990: median 5.0 µg/L from 15 readings1991: median 5.0 µg/L from 13 readings1992: median 4.0 µg/L from 15 readings1993: median 4.0 µg/L from 15 readings1994: median 4.0 µg/L from 28 readings1995: median 6.0 µg/L from 41 readings1996: median 9.0 µg/L from 25 readings1997: median 11 µg/L from 36 readings1998: median 7.0 µg/L from 22 readings1999: median 9.0 µg/L from 54 readings2000: median 10 µg/L from 43 readings2001: median 6.0 µg/L from 41 readings2002: median 7.0 µg/L from 68 readings2003: median 5.0 µg/L from 101 readings2004: median 3.0 µg/L from 33 readings2005: median 3.0 µg/L from 45 readings2006: median 3.0 µg/L from 19 readings2007: median 6.0 µg/L from 23 readings2008: median 5.0 µg/L from 14 readings2009: median 5.0 µg/L from 26 readings2010: median 5.0 µg/L from 16 readings2011: median 4.0 µg/L from 17 readings2012: median 6.5 µg/L from 23 readings2013: median 5.0 µg/L from 20 readings2014: median 6.4 µg/L from 15 readings2015: median 3.4 µg/L from 35 readings2016: median 5.3 µg/L from 20 readings2017: median 7.5 µg/L from 20 readings2018: median 7.6 µg/L from 18 readings2019: median 6.4 µg/L from 20 readings2020: median 6.4 µg/L from 20 readings2021: median 5.7 µg/L from 20 readings2022: median 6.7 µg/L from 20 readings2023: median 6.2 µg/L from 21 readings2024: median 5.6 µg/L from 20 readings2025: median 5.3 µg/L from 20 readings2026: median 4.8 µg/L from 19 readingsµg/L
Chlorophyll a the green pigment in algae: a direct measure of how much is growing
13 19801990200020102020 1975: median 2.0 µg/L from 10 readings1976: median 1.3 µg/L from 46 readings1977: median 1.2 µg/L from 19 readings1978: median 1.3 µg/L from 25 readings1979: median 0.6 µg/L from 19 readings1980: median 0.8 µg/L from 13 readings1981: median 0.6 µg/L from 13 readings1982: median 0.8 µg/L from 15 readings1983: median 1.4 µg/L from 18 readings1984: median 1.0 µg/L from 23 readings1987: median 0.7 µg/L from 15 readings1988: median 0.8 µg/L from 15 readings1989: median 1.0 µg/L from 15 readings1990: median 1.4 µg/L from 15 readings1991: median 1.4 µg/L from 13 readings1992: median 1.2 µg/L from 15 readings1993: median 2.0 µg/L from 14 readings1994: median 0.9 µg/L from 16 readings1995: median 1.6 µg/L from 14 readings1996: median 1.3 µg/L from 41 readings1997: median 2.4 µg/L from 38 readings1998: median 3.2 µg/L from 23 readings1999: median 4.8 µg/L from 43 readings2000: median 2.7 µg/L from 40 readings2001: median 2.1 µg/L from 39 readings2002: median 2.5 µg/L from 44 readings2003: median 1.5 µg/L from 77 readings2004: median 1.9 µg/L from 32 readings2005: median 1.1 µg/L from 16 readings2006: median 1.4 µg/L from 22 readings2007: median 1.0 µg/L from 22 readings2008: median 1.0 µg/L from 16 readings2009: median 0.8 µg/L from 4 readings2010: median 1.4 µg/L from 14 readings2011: median 1.9 µg/L from 17 readings2012: median 1.4 µg/L from 23 readings2013: median 1.6 µg/L from 20 readings2014: median 2.2 µg/L from 15 readings2015: median 0.7 µg/L from 44 readings2016: median 2.9 µg/L from 20 readings2017: median 1.9 µg/L from 20 readings2018: median 3.0 µg/L from 18 readings2019: median 2.2 µg/L from 20 readings2020: median 2.6 µg/L from 20 readings2021: median 1.8 µg/L from 20 readings2022: median 2.7 µg/L from 19 readings2023: median 1.9 µg/L from 20 readings2024: median 1.0 µg/L from 20 readings2025: median 1.3 µg/L from 20 readings2026: median 1.1 µg/L from 20 readingsµg/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

Reads as oligotrophic (few nutrients, little algae, usually clear).

IndexClass
From secchi depth (5.5 m, 2016–2025)35oligotrophic
From total phosphorus (6.1 µg/L, 2017–2026)30oligotrophic
From chlorophyll a (2.0 µg/L, 2017–2026)37oligotrophic

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

YearSecchi depthTotal phosphorusChlorophyll a
2026–4.8 µg/L (19)1.1 µg/L (20)
20255.9 m (19)5.3 µg/L (20)1.3 µg/L (20)
20246.5 m (20)5.6 µg/L (20)1.0 µg/L (20)
20234.4 m (20)6.2 µg/L (21)1.9 µg/L (20)
20225.7 m (20)6.7 µg/L (20)2.7 µg/L (19)
20215.5 m (17)5.7 µg/L (20)1.8 µg/L (20)
20205.5 m (20)6.4 µg/L (20)2.6 µg/L (20)
20195.9 m (20)6.4 µg/L (20)2.2 µg/L (20)
20184.2 m (18)7.6 µg/L (18)3.0 µg/L (18)
20175.6 m (20)7.5 µg/L (20)1.9 µg/L (20)
20165.9 m (20)5.3 µg/L (20)2.9 µg/L (20)
20157.6 m (20)3.4 µg/L (35)0.7 µg/L (44)
20148.1 m (15)6.4 µg/L (15)2.2 µg/L (15)
20135.9 m (20)5.0 µg/L (20)1.6 µg/L (20)
20125.9 m (23)6.5 µg/L (23)1.4 µg/L (23)
20113.9 m (17)4.0 µg/L (17)1.9 µg/L (17)
20106.3 m (16)5.0 µg/L (16)1.4 µg/L (14)
20099.4 m (4)5.0 µg/L (26)0.8 µg/L (4)
2008–5.0 µg/L (14)1.0 µg/L (16)
20079.0 m (7)6.0 µg/L (23)1.0 µg/L (22)
2006–3.0 µg/L (19)1.4 µg/L (22)
2005–3.0 µg/L (45)1.1 µg/L (16)
20046.5 m (31)3.0 µg/L (33)1.9 µg/L (32)
20036.8 m (47)5.0 µg/L (101)1.5 µg/L (77)
20026.5 m (35)7.0 µg/L (68)2.5 µg/L (44)
20017.2 m (40)6.0 µg/L (41)2.1 µg/L (39)
20006.2 m (40)10 µg/L (43)2.7 µg/L (40)
19997.1 m (34)9.0 µg/L (54)4.8 µg/L (43)
1998–7.0 µg/L (22)3.2 µg/L (23)
19977.5 m (2)11 µg/L (36)2.4 µg/L (38)
1996–9.0 µg/L (25)1.3 µg/L (41)
199510.3 m (6)6.0 µg/L (41)1.6 µg/L (14)
199410.3 m (16)4.0 µg/L (28)0.9 µg/L (16)
1993–4.0 µg/L (15)2.0 µg/L (14)
199211.1 m (11)4.0 µg/L (15)1.2 µg/L (15)
199110.8 m (12)5.0 µg/L (13)1.4 µg/L (13)
19909.4 m (14)5.0 µg/L (15)1.4 µg/L (15)
198912.5 m (2)4.0 µg/L (15)1.0 µg/L (15)
198811.3 m (11)4.5 µg/L (16)0.8 µg/L (15)
198712 m (8)8.0 µg/L (15)0.7 µg/L (15)
19868.5 m (3)6.0 µg/L (16)–
19856.2 m (21)9.0 µg/L (24)–
19847.5 m (24)13 µg/L (26)1.0 µg/L (23)
19836.1 m (17)12 µg/L (18)1.4 µg/L (18)
19827.6 m (14)11 µg/L (13)0.8 µg/L (15)
19818.8 m (9)10 µg/L (13)0.6 µg/L (13)
19809.0 m (13)8.0 µg/L (13)0.8 µg/L (13)
19799.7 m (13)7.0 µg/L (16)0.6 µg/L (19)
19786.1 m (14)8.0 µg/L (26)1.3 µg/L (25)
19778.3 m (10)7.0 µg/L (18)1.2 µg/L (19)
19765.5 m (17)10 µg/L (33)1.3 µg/L (46)
19757.0 m (17)8.0 µg/L (15)2.0 µg/L (10)
19745.8 m (3)8.5 µg/L (4)–
19736.4 m (5)6.0 µg/L (5)–

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

  • 0500730 OKANAGAN L NORTH OKANAGAN CENTRE 779 readings
  • 0500239 OKANAGAN L CENTRAL ARMSTRONG ARM 736 readings
  • 0500454 OKANAGAN L SOUTH PRAIRIE C - OK1 - N SUMMERLAND STP OUTFALL DIFFUSER 727 readings
  • 0500236 OKANAGAN L D/S KELOWNA STP (DEEP) 722 readings
  • E206611 OKANAGAN L NEAR VERNON OUTFALL 341 readings
  • E223295 OKANAGAN LAKE OPP. RATTLESNAKE ISLAND 220 readings
  • 0500729 OKANAGAN L STH. SQUALLY PT. 210 readings
  • 0500458 OKANAGAN LAKE KIN BEACH WEST 190 readings
  • 0500456 OKANAGAN L UPS KELOWNA STP (DEEP) 179 readings
  • 0500238 OKANAGAN L CENTRAL VERNON ARM 165 readings
  • 0500460 OKANAGAN LAKEHEAD WEST 139 readings
  • 0500240 OKANAGAN L OPP. TROUT HATCHERY 135 readings
  • 0500911 OKANAGAN L. @ PEACHLAND CR. 119 readings
  • 0500912 OKANAGAN L. @ TREPANIER CR. 118 readings
  • 0500242 OKANAGAN L OPP. KELOWNA OUTFALL (SHALLOW) 115 readings
  • E206570 OKANAGAN LAKE SOUTH POWERS CREEK 96 readings
  • 0500455 OKANAGAN LK/SOUTH KELOWNA STP (SHALLOW) 62 readings
  • E227650 OKANAGAN LAKE AT SUMMERLAND STP OUTFALL; PE-13627 31 readings
  • 0500874 OKANAGAN L NEAR SHORE OKANAGAN CENTRE 16 readings
  • 0500873 OKANAGAN L NEAR MOUTH VERNON CREEK 15 readings

And 35 more sites.

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.