Swimmers have been warned away from Queenstown’s popular Lake Hayes after it recorded more than three-and-a-half times the level of E.coli considered safe to swim in.
The Otago Regional Council has warned swimmers to stay out of the water until further testing is completed after it found E.coli levels of 921/100ml in the lake.
Water quality guidelines state levels with less than 260 E.coli/100ml are considered safe and levels above 550 E.coli/100ml pose a health risk. The bacteria can cause diarrhea, abdominal pain, and fever.
“ORC staff are carrying out further water quality testing this week to determine the cause of the E.coli contamination and whether an advisory against swimming in the area is required,” said the regional council.
The results of the testing should be available by Wednesday but in the meantime “people considering swimming in the lake should hold off”.
The picturesque lake near Arrowtown, north of Queenstown, is a popular spot with visitors, campers and motorhome users and the walking track around the water is well used by cyclists, runners and walkers.
Queenstown mayor Jim Boult lives by the lake and he has taken a keen interest in the quality of its environment. New camping and parking restrictions are being implemented over the summer.
The lake and its surroundings are a habitat for threatened species such as the native koaro fish and swamp birds Australasian bittern and great crested grebe.
ORC’s manager for resource science, Dean Olsen, said a number of factors such as recent rainfall, water flow, bird activity, stock in waterways can influence bacteria counts in water.
Even whether it was a cloudy or sunny day could affect quality as E.coli often died quickly in clear water when exposed to sunlight.
For more information on when water is safe to swim in across Otago, contact the ORC or visit www.orc.govt.nz.