Monday, 10 May 2021, 4:14 pm Canterbury DHB’s Community and Public Health unit has issued a health warning for the Cust Main Drain at Skewbridge. The warning follows a high cover of potentially toxic algae (benthic cyanobacteria), as well as detaching mats, being found in the Cust Main Drain. People should avoid the area and animals, particularly dogs, should not be allowed near the water until the health warning has been lifted. People are advised to treat every low-flowing river cautiously, check for the presence of benthic cyanobacteria and avoid contact. Dr Cheryl Brunton, Canterbury Medical Officer of Health, says the algae look like dark brown to black mats