| Barnsjön | |
| Coords: | 59.2266°N 18.2355°W |
| Outflow: | Tyresö-Flaten |
| Basin Countries: | Sweden |
| Area: | 2ha |
| Elevation: | 30m (100feet) |
| Cities: | Tyresö |
| Pushpin Map: | Sweden Stockholm |
| Pushpin Map Alt: | Location in Stockholm County, Sweden |
| Reference: | [1] [2] |
Barnsjön (Swedish for "the Child Lake") is a small lake within the Tyresån Lake System in Tyresö Municipality south of Stockholm, Sweden.
The lake, situated between the residential areas Trollbäcken and Bollmora, empties into Lake Tyresö-Flaten through the brook Prästängsdiket.[3] It is regarded as an important local recreational milieu. It is popular for both fishing and bathing. There are two municipal baths by the lake.[4]
Barnsjön is a forest lake poor in nutrients. With a low buffering capacity, the lake is sensitive to acid deposits and has an acidity at about pH 7. It is therefore regarded as important to avoid contaminations within its catchment area.