BC lake · 16 km² · Nechako River watershed

Nulki Lake

Its median summer Secchi depth over 2022–2023 was 1.2 m, from 16 readings. Murkier than 97% of the 122 BC lakes with at least 5 readings.

The readings

111 summer readings on record from 1983 to 2023, at 3 sampling sites.

	Median, latest 10 sampled years	Compared with BC lakes
Secchi depth	1.2 m 2022–2023, 16 readings	Murkier than 97% of the 122 BC lakes with at least 5 readings.
Total phosphorus	85 µg/L 2021–2023, 57 readings	Higher than 96% of the 269 BC lakes with at least 5 readings.
Chlorophyll a	44 µg/L 2021–2023, 28 readings	Higher than 99% 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

Total phosphorus the nutrient that most often feeds algae in BC lakes

Chlorophyll a the green pigment in algae: a direct measure of how much is growing

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 secchi depth (1.2 m, 2022–2023)	58	eutrophic
From total phosphorus (85 µg/L, 2021–2023)	68	eutrophic
From chlorophyll a (44 µg/L, 2021–2023)	68	eutrophic

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

Year	Secchi depth	Total phosphorus	Chlorophyll a
2023	1.1 m (8)	91 µg/L (16)	32 µg/L (8)
2022	1.2 m (8)	67 µg/L (20)	46 µg/L (10)
2021	–	92 µg/L (21)	90 µg/L (10)
1997	–	90 µg/L (2)	–
1995	–	26 µg/L (2)	–
1990	–	36 µg/L (1)	–
1989	–	63 µg/L (2)	–
1987	–	43 µg/L (2)	–
1983	–	72 µg/L (1)	–

Median of each year's May to October readings; the number of readings is in brackets.

Where it was sampled

E288730 NULKI LAKE DEEP STATION 103 readings
0400574 NULKI L NEAR CENTER 11 readings
E227173 NULKI LAKE LITTORAL SITE 1 reading

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.