Media release

High levels of E. coli in Lake Hayes

Monday 18 December 2017

Otago Regional Council (ORC) water quality samples taken from Lake Hayes have shown high levels of the bacteria E.Coli.

Government water quality guidelines for recreational swimming areas are that those with less than 260 E.coli/100ml should be safe, whereas water with more than 550 E.coli/100ml poses a health risk. ORC’s most recent sampling in the area showed E.coli levels at 921/100ml.

ORC Manager Resource Science Dean Olsen said a number of factors such as recent rainfall, water flow, bird activity, stock in waterways or even whether it is a cloudy or sunny day, (as E.coli often dies quickly in clear water when exposed to sunlight), can influence observed bacteria counts.

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. The results of this testing should be available by Wednesday.

People considering swimming in the lake should hold off in the meantime, pending further testing.

To find out when the water is safe to swim in, contact the ORC or visit

For more information contact:

Dean Olsen
ORC Manager Resource Science
Ph 03 470 7408 or 027 602 2737