Monitoring of the region's swimming spots last summer produced some pleasing results, but concerns remain at some key sites, Environment Canterbury says.
ECan is due to start its summer monitoring of more than 100 rivers, lakes and coastal areas in November to ensure they are safe for swimming. It will use last summer’s results as a starting point.
The Ashley-Rakahuri and Hurunui rivers and Lyell Creek in Kaikōura are among the areas of concern.
ECan will test the water for faecal bacteria (E. coli and enterococci) and check for toxic algae (cyanobacteria), which can harm the health of people and animals, especially dogs.
Five freshwater sites showed improvement, but seven sites produced worse results than the 2022/23 summer, including two sites on the Ashley-Rakahuri River, which slipped from 'good' gradings to 'fair'.
Akaroa Beach and Tikao Bay on Banks Peninsula have improved, moving from ‘poor’ to ‘fair’ and are now considered generally suitable for swimming.
Cass Bay, Church Bay, and Charteris Bay are graded suitable for swimming. Corsair Bay, Rāpaki Bay, Governors Bay, Diamond Harbour and Purau Bay are graded unsuitable.
Moriarty said water quality can change from week-to-week or even day-to-day.
“It’s best to check the LAWA website for up-to-date information each time you head out,” she said.
The council believes the results are due to combination of factors including bird and livestock poop, landuse practices and climate change.
‘‘Environment Canterbury is doing a lot of work around the estuary and we are working with Ngāi Tūāhuriri,’’ Moriarty said.
‘‘It is also something to consider if you are practising mahinga kai, being careful with your whitebait gear and making sure your food is well cooked.’’
A testing site on the Ashley-Rakahuri River at State Highway 1 produced a 'good' grading, while 'very good' sites were Pegasus Beach, Waikuku Beach, Woodend Beach and Pegasus Lake.
Hurunui River sites produced 'fair' and 'very poor' ratings, while a Waipara River site was 'poor', likely due to nutrients from livestock farming and climate change, Moriarty said.
‘‘There are things we can do with our planning and our consenting and looking at the landuse and activities on the water.’’
But she stressed the gradings were guidelines and did not indicate there was a ban on swimming or recreational activities.
Sites at Hanmer River, Waiau Uwha River and Motunau Beach scored 'good' gradings, while Gore Bay produced a 'very good' result.
In Kaikōura, the Lyell Creek / Waikōau Lagoon site produced a 'very poor' result, similar to Christchurch’s Ōtākaro Avon River, Moriarty said.
‘‘You often get that in small towns and Kaikōura has had the earthquakes, which led to a fragile water system due to lateral spreading damage and to the main sewer pipes.’’
Brunton said it could take five years or more for water ways to recover after a major event.
Armers, Gooches, Peketā and South Bay beaches all produced 'good' results, while Mangāmāunu has a 'very good' grading.
Swimmers are advised to check the LAWA (Land Air Water Aotearoa) website before taking a dip this summer, and to avoid swimming holes for 48 hours after a heavy rainfall.
- Find out where you can and cannot swim at www.ecan.govt.nz/your-region/your-environment/water/swimming-water-quality.
By David Hill, Local Democracy Reporter
■ LDR is local body journalism co-funded by RNZ and NZ On Air
