Summer students are critical to water monitoring efforts

Monitoring the water of Canterbury's favourite contact recreation sites is one of the lesser-seen - but nonetheless critical - jobs our summer students carry out.

The summer internship programme gives environmentally-inclined students a chance to put into effect what they have been learning in their tertiary studies.

One such student, South Africa-born New Zealander Keagan Hopper, recently carried out a run of site testing in North Canterbury on a balmy February day.

Keagan grew up in Hokitika before making the move east to Christchurch – at first to University of Canterbury, then Lincoln University. This is his second term with us as a summer student in the recreational water monitoring team.

Getting a grip on North Canterbury's waterways

cyanobacteria on rocks

Cyanobacteria appears as on rocks as thick dark brown or black mats

Keagan tested five rivers and two coastal sites on the day. The first stop was the Rakahuri/Ashley River at State Highway 1.

Out of the boot came waders, sample bottles, and even a bathyscope - a road cone-like object water samplers use to get an accurate understanding of what's going on under the water without ripples or glare interfering.

"We use it to get an estimate on what percentage of the riverbed is covered with cyanobacteria," Keagan said.

Cyanobacteria (also called blue-green algae or toxic algae) makes animals and humans extremely sick and can be fatal to dogs. Dogs are particularly at risk if they swallow the algae or algal mats when swimming or drinking from rivers, ponds and lakes.

The visual estimate from the bathyscope gives an initial indication - if it's over the 15% threshold, monitors conduct a transect of the river to get a more accurate result. It is the transect results which are used to advise whether a river should go into warning or not.

The bathyscope can be used to do several transects or cuts across the riverbed, where the cyanobacteria cover is counted at multiple points across the width of the river.

Week by week observations

Motunau Beach

Keagan tested for Enterococci at Motunau Beach

After the visual estimate, Keagan headed back into the river with a bottle and claw to collect an E. coli sample to be taken to a laboratory for testing.

"It took a while to get used to visually estimating cover, but I'm getting quite good at it now. I usually end up within a couple of percentage points of the transect observation," he said.

"It's really interesting to me, seeing how quickly - just a matter of a week sometimes - a waterway can change. It's what keeps me coming back.

"This is my second time as a water monitoring summer student and I can definitely see myself returning for a third year," Keagan said.

After the Ashley/Rakahuri, Keagan headed to Waipara Boys Brigade, two sites on the Hurunui River, and one on the Waiau River. He tested coastal sites Motunau Beach and Gore Bay too.

At the coastal sites Keagan wasn't looking for cyanobacteria and E. coli, but Enterococci. The results of this testing can be found under 'Can I Swim Here?' on