Opalsøen

Denmark Lake 1 - Excellent

Opalsøen is a freshwater lake located in a former granite quarry that was used until the 1970s. The bathing area features an 8-metre designated swimming zone and is part of the Natura 2000 protected area Hammeren and Slotslyngen, which includes EU bird protection zones. The lake has a granite and compacted sand shoreline with multiple plateau levels. Water conditions are generally calm with no detectable current.

Reviews

No reviews yet.

Write a review

Photos

Upload a photo

Water

Freshwater lake formed in a former granite quarry. The lake is very deep with no visible bottom. Water flow is consistently calm. Salt content is less than 0.05 percent.

Location

Opalsøen is located on the island of Bornholm, Denmark. The bathing station is managed by Bornholms Regionskommune. Parking and public toilets are available at the bathing site.

Facilities

Shelter and covered barbecue area at the bathing site. Tables and benches distributed throughout the area. Public toilet and parking available.

Season

Official monitoring period is 1 June to 1 September.

Water Quality

The bathing station was designated in 2020 and has not yet received an official classification. Water quality classification will be assigned after 16 test samples have been reported to the EU. Six water samples are collected annually and analysed for the indicator bacteria E. coli and enterococci. Control samples show minor, short-term faecal contamination with slightly reduced water quality observed periodically. No sewage overflow outlets discharge into the lake.

Risks

Faecal contamination from birds in the adjacent EU bird protection area is the primary pollution risk. Blue-green algae blooms and phytoplankton can occur, especially during warm periods in July and August with calm, sunny conditions. Macroalgae accumulation can occur and may promote bacterial growth. Sudden contamination events can occur from accidents. Bathing is not recommended immediately after heavy rainfall or when water smells of sewage or contains waste.