PlaceDossier / BC places / Lakes
BC lake · 21 km² · Nechako River watershed
Tachick Lake
Its median summer total phosphorus over 2015–2026 was 39 µg/L, from 130 readings. Higher than 92% of the 100 BC lakes with enough recent readings.
The readings
229 summer readings from open water on record from 1983 to 2026, at 3 sampling sites.
| Median since 2012 | Compared with BC lakes | |
|---|---|---|
| Secchi depth | Too few readings to judge 21 readings since 2012, in 2 years | Too few readings to compare (21 readings since 2012, in 2 years). |
| Total phosphorus | 39 µg/L 2015–2026, 130 readings | Higher than 92% of the 100 BC lakes with enough recent readings. |
| Chlorophyll a | 13 µg/L 2015–2026, 65 readings | Higher than 94% 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
Reads as eutrophic (rich in nutrients, with more algae and weed growth).
| Index | Class | |
|---|---|---|
| From total phosphorus (39 µg/L, 2015–2026) | 57 | eutrophic |
| From chlorophyll a (13 µg/L, 2015–2026) | 56 | eutrophic |
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 (21 readings since 2012, in 2 years).
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 | – | 66 µg/L (18) | 21 µg/L (9) |
| 2025 | 1.6 m (11) | 55 µg/L (22) | 16 µg/L (11) |
| 2024 | 1.4 m (10) | 31 µg/L (21) | 12 µg/L (10) |
| 2017 | – | 42 µg/L (22) | 8.7 µg/L (11) |
| 2016 | – | 37 µg/L (25) | 9.0 µg/L (12) |
| 2015 | – | 30 µg/L (22) | 11 µg/L (12) |
| 1997 | – | 80 µg/L (2) | – |
| 1995 | – | 32 µg/L (3) | – |
| 1990 | – | 19 µg/L (2) | – |
| 1987 | – | 32 µg/L (3) | – |
| 1984 | – | 40 µg/L (2) | – |
| 1983 | – | 42 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
- 0400753 Near centre 225 readings
- 0400927 East end near Stony C 3 readings
- E227185 Littoral site 1 reading
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.