Why rank lakes by phosphorus?

Phosphorus is usually what limits how much algae a lake can grow, so it is the earliest signal that a lake is under nutrient pressure. It is also the measurement these agencies publish most consistently, which makes it the fairest way to compare lakes across a country.

Is a low-phosphorus lake safe to swim in?

Not necessarily. A lightly loaded lake can still carry bacteria, a seasonal algal bloom, or contaminants that a nutrient reading does not cover. Check the local authority notice for the day you plan to go.

What is a typical phosphorus level in Sweden?

The median measured lake in Sweden reads 9.2 µg/L of total phosphorus. Lakes below roughly 10 µg/L are considered nutrient-poor and usually run clear; above about 30 µg/L a lake is generally nutrient-rich and more likely to green up in summer.

Cleanest lakes in Sweden

Cleanest lakes in Sweden: 55 named lakes have an official total-phosphorus reading. The 20 below carry the lowest nutrient load — a measurement, not a LakeQuality A–F grade.

Lake map

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Lowest phosphorus readings in Sweden

Phosphorus is the nutrient that feeds algae growth, so the lakes at the top of this table are the least loaded ones the Sweden monitoring programme has measured. The median measured lake in Sweden reads 9.2 µg/L.

Lake	Place	Total phosphorus	Chlorophyll-a	Secchi	Year
Vastra Solsjon	—	1.9 µg/L	2.1 µg/L	6.7 m	2023
Stor-Tjultrasket Lake	—	2.7 µg/L	0.90 µg/L	8.5 m	2023
Stor-Bjorsjon	—	2.8 µg/L	1.3 µg/L	4.3 m	2023
Vittrasket Lake	—	3.5 µg/L	1.1 µg/L	8.0 m	2023
Bastetrask Lake	—	3.6 µg/L	1.4 µg/L	3.5 m	2023
Bosjon	—	3.7 µg/L	1.6 µg/L	3.7 m	2023
Spjutsjon	—	3.9 µg/L	1.3 µg/L	6.0 m	2023
Limmingsjon	—	4.3 µg/L	2.9 µg/L	3.4 m	2023
Fyrsjon	—	4.9 µg/L	2.2 µg/L	3.9 m	2023
Hokesjon	—	5.2 µg/L	2.8 µg/L	6.7 m	2021
Hjartsjon	—	5.3 µg/L	1.3 µg/L	5.6 m	2023
Oversjon	—	5.4 µg/L	3.0 µg/L	4.2 m	2021
Ojsjon	—	5.9 µg/L	2.3 µg/L	5.2 m	2023
Stensjon	—	5.9 µg/L	2.2 µg/L	2.2 m	2023
Stor-Arasjon	—	5.9 µg/L	2.7 µg/L	3.4 m	2023
Ulvsjon	—	6.1 µg/L	1.9 µg/L	3.7 m	2021
Fjatsjon Ovre	—	6.5 µg/L	1.7 µg/L	4.1 m	2023
Hallsjon	—	6.7 µg/L	2.2 µg/L	3.2 m	2021
Grissjon	—	6.9 µg/L	3.2 µg/L	2.5 m	2021
Fjarasjo Lake	—	7.1 µg/L	2.8 µg/L	3.5 m	2023

Showing 20 of 55 named lakes. Open a county or place page for the rest.

Frequently asked questions

Which lakes in Sweden are the cleanest?: 55 named lakes in Sweden have an official total-phosphorus reading. This page ranks the 20 lowest. Phosphorus is the nutrient that feeds algae growth, so a low reading means a lightly loaded lake — it is not a swim-safety class and not a LakeQuality A–F grade.
Why rank lakes by phosphorus?: Phosphorus is usually what limits how much algae a lake can grow, so it is the earliest signal that a lake is under nutrient pressure. It is also the measurement these agencies publish most consistently, which makes it the fairest way to compare lakes across a country.
Is a low-phosphorus lake safe to swim in?: Not necessarily. A lightly loaded lake can still carry bacteria, a seasonal algal bloom, or contaminants that a nutrient reading does not cover. Check the local authority notice for the day you plan to go.
What is a typical phosphorus level in Sweden?: The median measured lake in Sweden reads 9.2 µg/L of total phosphorus. Lakes below roughly 10 µg/L are considered nutrient-poor and usually run clear; above about 30 µg/L a lake is generally nutrient-rich and more likely to green up in summer.