The grades have shown that 77% of the region’s monitored swimming sites are suitable for contact recreation (swimming and other water-based activities) — the same result as the previous season.
Each summer, starting in mid-November, Environment Canterbury monitors 52 popular freshwater sites and 47 coastal sites.
"Our teams are out weekly throughout the summer season collecting water samples and testing for faecal indicator bacteria to determine which sites are safe for everyone to enjoy," said Environment Canterbury acting chief scientist Dr Elaine Moriarty in a statement.
As the long-term grades, which summarise the last five years, are only updated after the end of each season, weekly water sampling provides a more up-to date picture of water quality.
Dr Moriarty advised people to use Land Air Water Aotearoa’s (LAWA) Can I swim here? website to check the current water quality before swimming or engaging in water activities.
Toxic algal blooms can occur in all freshwater sites during the season, and temporary warnings will be issued on sites that are monitored.
Long-term and weekly grades, and toxic algae warnings, are available to view on the LAWA website.
She also recommended avoiding swimming for 48 hours after rain, because rain could wash bacteria from roads, paddocks and other sources into the waterways.
"A handy guide is, if you can’t see your toes when standing knee deep in water, then water quality is not good enough for swimming."
Caroline Bay has good water quality for swimming near the yacht club and in the middle of the beach.
However, it is best to avoid swimming near the stormwater outlet "Whale Creek", especially up to 48 hours after rainfall.
Based on this year’s grades, in Waimate, the Hakataramea River at the highway, Waihao River at Bradshaw’s Road and Gum Tree Road are good swimming spots this year.
Pareora River at the Huts settlement and at Evan’s Crossing should both be avoided, as well as Waihao River at Black Hole.
In the Timaru District, all sites on the Opihi River are good for swimming, as well as all monitored spots on the Waihī River.
However, the Temuka River/Te Uma Kaha at State Highway1 should be avoided.
There is very good water quality at the Lake Ruataniwha camping ground, Lake Opuha recreation reserve, Loch Cameron south bank and Lake Tekapo beach.
Lake Alexandrina at Bottom Huts has been downgraded from fair to poor this season, making it unsuitable for contact recreation.
This lake has experienced variable water quality since monitoring began in 2012, with grades improving from poor in the mid-2010s to good between 2019-23, before recent deterioration due to more frequent high E. coli concentrations during summer monitoring periods.
"We will continue to work with local councils and the community to identify the sources of the contamination and improve water quality at these popular recreational sites," Dr Moriarty said.
During the 2024-25 summer, 46 temporary public health warnings were issued across 34 sites, including 28 warnings for faecal contamination and 18 for toxic algae.
"Lake Hood’s E. coli long-term grade, at the Baylis Beach site, remains suitable for recreation but has declined from very good to good. However, given the recent history of toxic algae blooms, we anticipate that health warnings may be required again this season," Dr Moriarty said.
"These temporary warnings are a crucial part of keeping the public safe."
— Allied Media
