PlaceDossier / BC places / Lakes

BC lake · 307 km² · Shuswap Lake watershed

Shuswap Lake

Its median summer Secchi depth over 2012–2025 was 5.8 m, from 234 readings. Clearer than 64% of the 62 BC lakes with enough recent readings.

The readings

2,285 summer readings from open water on record from 1971 to 2026, at 43 sampling sites.

Median since 2012Compared with BC lakes
Secchi depth5.8 m
2012–2025, 234 readings		Clearer than 64% of the 62 BC lakes with enough recent readings.
Total phosphorus10 µg/L
2012–2026, 454 readings		Higher than 53% of the 100 BC lakes with enough recent readings.
Chlorophyll a1.7 µg/L
2012–2026, 348 readings		Lower than 54% of the 83 BC lakes with enough recent readings (lower is clearer).
Secchi depth how deep a black-and-white disc stays visible: deeper means clearer water
0510 19801990200020102020 1971: median 3.2 m from 2 readings1973: median 7.9 m from 5 readings1974: median 7.9 m from 3 readings1975: median 3.9 m from 10 readings1976: median 5.8 m from 14 readings1977: median 11.7 m from 9 readings1978: median 8.0 m from 12 readings1979: median 9.0 m from 10 readings2004: median 7.9 m from 13 readings2009: median 9.6 m from 21 readings2010: median 6.9 m from 29 readings2011: median 4.8 m from 17 readings2012: median 4.6 m from 25 readings2013: median 5.3 m from 15 readings2014: median 7.9 m from 19 readings2015: median 8.1 m from 41 readings2016: median 4.7 m from 20 readings2017: median 4.2 m from 13 readings2018: median 2.4 m from 18 readings2019: median 6.5 m from 56 readings2020: median 7.4 m from 8 readings2021: median 0.5 m from 5 readings2022: median 9.4 m from 2 readings2023: median 4.9 m from 5 readings2024: median 5.3 m from 5 readings2025: median 10.8 m from 2 readingsm
Total phosphorus the nutrient that most often feeds algae in BC lakes
31030100 19801990200020102020 1971: median 5.0 µg/L from 5 readings1973: median 40 µg/L from 1 reading1974: median 10 µg/L from 5 readings1975: median 11 µg/L from 10 readings1976: median 4.5 µg/L from 18 readings1977: median 5.0 µg/L from 8 readings1978: median 6.0 µg/L from 11 readings1979: median 6.5 µg/L from 10 readings1987: median 11 µg/L from 16 readings1988: median 10 µg/L from 15 readings1989: median 11 µg/L from 40 readings1990: median 5.0 µg/L from 42 readings1991: median 5.0 µg/L from 33 readings1992: median 3.0 µg/L from 28 readings1993: median 3.0 µg/L from 27 readings1994: median 7.0 µg/L from 27 readings1995: median 3.5 µg/L from 20 readings1997: median 9.0 µg/L from 25 readings1998: median 3.0 µg/L from 25 readings1999: median 8.0 µg/L from 26 readings2000: median 8.0 µg/L from 26 readings2001: median 4.0 µg/L from 26 readings2002: median 84 µg/L from 48 readings2003: median 4.0 µg/L from 28 readings2004: median 2.0 µg/L from 67 readings2005: median 2.0 µg/L from 48 readings2006: median 2.0 µg/L from 50 readings2007: median 5.0 µg/L from 40 readings2008: median 4.0 µg/L from 59 readings2009: median 3.0 µg/L from 45 readings2010: median 4.0 µg/L from 33 readings2011: median 5.0 µg/L from 36 readings2012: median 8.7 µg/L from 35 readings2013: median 16 µg/L from 28 readings2014: median 19 µg/L from 36 readings2015: median 2.9 µg/L from 53 readings2016: median 15 µg/L from 31 readings2017: median 5.4 µg/L from 13 readings2018: median 15 µg/L from 22 readings2019: median 4.1 µg/L from 64 readings2020: median 11 µg/L from 14 readings2021: median 11 µg/L from 21 readings2022: median 19 µg/L from 19 readings2023: median 16 µg/L from 34 readings2024: median 10 µg/L from 32 readings2025: median 10.0 µg/L from 34 readings2026: median 7.6 µg/L from 18 readingsµg/L
Chlorophyll a the green pigment in algae: a direct measure of how much is growing
13 19801990200020102020 1975: median 2.1 µg/L from 5 readings1976: median 1.5 µg/L from 17 readings1977: median 0.6 µg/L from 7 readings1978: median 1.0 µg/L from 12 readings1979: median 0.6 µg/L from 10 readings1989: median 7.2 µg/L from 4 readings2002: median 1.9 µg/L from 12 readings2004: median 0.6 µg/L from 1 reading2006: median 1.6 µg/L from 23 readings2007: median 1.8 µg/L from 17 readings2008: median 1.4 µg/L from 29 readings2009: median 0.8 µg/L from 21 readings2010: median 1.2 µg/L from 28 readings2011: median 2.2 µg/L from 20 readings2012: median 2.0 µg/L from 23 readings2013: median 2.2 µg/L from 15 readings2014: median 1.9 µg/L from 18 readings2015: median 1.2 µg/L from 40 readings2016: median 1.6 µg/L from 12 readings2017: median 1.5 µg/L from 11 readings2018: median 5.1 µg/L from 8 readings2019: median 2.2 µg/L from 49 readings2020: median 3.3 µg/L from 9 readings2021: median 1.3 µg/L from 10 readings2022: median 4.0 µg/L from 8 readings2023: median 1.1 µg/L from 31 readings2024: median 1.7 µg/L from 94 readings2025: median 1.0 µg/L from 14 readings2026: median 1.8 µg/L from 6 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 (5.8 m, 2012–2025)35oligotrophic
From total phosphorus (10 µg/L, 2012–2026)37oligotrophic
From chlorophyll a (1.7 µg/L, 2012–2026)36oligotrophic

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
2026–7.6 µg/L (18)1.8 µg/L (6)
202510.8 m (2)10.0 µg/L (34)1.0 µg/L (14)
20245.3 m (5)10 µg/L (32)1.7 µg/L (94)
20234.9 m (5)16 µg/L (34)1.1 µg/L (31)
20229.4 m (2)19 µg/L (19)4.0 µg/L (8)
20210.5 m (5)11 µg/L (21)1.3 µg/L (10)
20207.4 m (8)11 µg/L (14)3.3 µg/L (9)
20196.5 m (56)4.1 µg/L (64)2.2 µg/L (49)
20182.4 m (18)15 µg/L (22)5.1 µg/L (8)
20174.2 m (13)5.4 µg/L (13)1.5 µg/L (11)
20164.7 m (20)15 µg/L (31)1.6 µg/L (12)
20158.1 m (41)2.9 µg/L (53)1.2 µg/L (40)
20147.9 m (19)19 µg/L (36)1.9 µg/L (18)
20135.3 m (15)16 µg/L (28)2.2 µg/L (15)
20124.6 m (25)8.7 µg/L (35)2.0 µg/L (23)
20114.8 m (17)5.0 µg/L (36)2.2 µg/L (20)
20106.9 m (29)4.0 µg/L (33)1.2 µg/L (28)
20099.6 m (21)3.0 µg/L (45)0.8 µg/L (21)
2008–4.0 µg/L (59)1.4 µg/L (29)
2007–5.0 µg/L (40)1.8 µg/L (17)
2006–2.0 µg/L (50)1.6 µg/L (23)
2005–2.0 µg/L (48)–
20047.9 m (13)2.0 µg/L (67)0.6 µg/L (1)
2003–4.0 µg/L (28)–
2002–84 µg/L (48)1.9 µg/L (12)
2001–4.0 µg/L (26)–
2000–8.0 µg/L (26)–
1999–8.0 µg/L (26)–
1998–3.0 µg/L (25)–
1997–9.0 µg/L (25)–
1995–3.5 µg/L (20)–
1994–7.0 µg/L (27)–
1993–3.0 µg/L (27)–
1992–3.0 µg/L (28)–
1991–5.0 µg/L (33)–
1990–5.0 µg/L (42)–
1989–11 µg/L (40)7.2 µg/L (4)
1988–10 µg/L (15)–
1987–11 µg/L (16)–
19799.0 m (10)6.5 µg/L (10)0.6 µg/L (10)
19788.0 m (12)6.0 µg/L (11)1.0 µg/L (12)
197711.7 m (9)5.0 µg/L (8)0.6 µg/L (7)
19765.8 m (14)4.5 µg/L (18)1.5 µg/L (17)
19753.9 m (10)11 µg/L (10)2.1 µg/L (5)
19747.9 m (3)10 µg/L (5)–
19737.9 m (5)40 µg/L (1)–
19713.2 m (2)5.0 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

  • E206771 Tb # 5 447 readings
  • 0500124 Opposite Marble Point 283 readings
  • 0500123 West of Sorrento 183 readings
  • E206770 Tb # 4 171 readings
  • E208721 Off Broken Point 110 readings
  • E208718 Off Canoe Point 108 readings
  • E208722 Off Encounter Point 108 readings
  • E263504 100 m north Idz 103 readings
  • E208723 Off Armstrong Point 77 readings
  • E206768 Tb # 2 61 readings
  • 0500555 Blind bay S.e 50 readings
  • E206769 Tb # 3 41 readings
  • E207579 Tb #6 40 readings
  • E208734 At Sorrento 36 readings
  • E208730 At Eagle bay 35 readings
  • E208724 Off Mcbride Point 30 readings
  • E222131 At Wild Rose bay 30 readings
  • E208729 At Angemont 26 readings
  • E208731 At Magna bay 26 readings
  • E208733 At Scotch Ck 26 readings

And 23 more sites.

Left out: 105 readings at 5 sites whose names put them away from the open lake

  • E263503 At City of Salmon arm Stp Discharge 89 readings; an outfall or discharge
  • E272408 Nielsen beach north - Control 5 readings; on the shore
  • E276603 Nielsen beach 4 readings; on the shore
  • E334888 The Owners, Strata Plan Kas 3536 - Diffuser at surface 4 readings; an outfall or discharge
  • E334889 The Owners, Strata Plan Kas 3536 - Diffuser at Bottom 3 readings; 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.