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Lake Clearwater, in the foothills of Mid-Canterbury.
Lake Clearwater is no longer clear.
Conservationists are upset that a once pristine Canterbury lake loved by fishermen and tourists has been shut down after toxic algal blooms began to cloud the water.
Authorities have partly blamed the lake’s condition on the farm community’s gate, saying runoff from farmland has contaminated it with nutrients.
But agricultural representatives say nearby natural wetlands and pothole discharges into the lake are also responsible for its condition.
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The Canterbury District Health Board (CDHB) issued a public health advisory on Monday for Lake Clearwater, which is located in the Ashburton Lakes basin area, after high concentrations of dangerous blue-green algae were detected.
Regional Forest and Bird Conservation Manager Debs Martin was at the lake this week visiting her family and was “appalled by the brown, cloudy lake water.”
“Right now it looks like pea soup and is not safe to use. It’s just horrible, ”he said.
“You should be able to see the depths of the lake, this is how the lake got its name and why fishermen and tourists love it so much.”
Martin said Lake Clearwater is incredibly important to wildlife, but the diving birds that live in the lake now cannot see their prey in the murky water.
“We have destroyed their only home. Responsible councils must do better. “
Supplied.
Toxic blue-green algae (cyanobacteria) visible in Central Otago’s Lake Hayes (File photo).
The latest Environment Canterbury report shows that Clearwater Lake is contaminated with nutrients from runoff from farmland and has not met the standards of the Canterbury Regional Land and Water Plan since 2005.
Other lakes in the area are in worse shape, Martin said.
“Neither regional nor district councils are doing enough to protect fresh water… they must act now.
“We could lose these incredible natural lakes and essential habitats, I am concerned that it is already too late.”
Forest and Bird wants to see a robust compliance and enforcement system, like Lake Taupō, implemented in New Zealand.
Federated Farmers Mid-Canterbury Provincial President David Clark said: “There are three problems with Lake Clearwater: nitrogen from farmland, discharge from septic tanks from Clearwater pothole outflows, and from natural wetlands in the Ashburton Gorge watershed.
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A raft of blue-green algae in the Hutt River.
“There has been a management plan in the Ashburton Gorge watershed for several years with all the lakes identified as sensitive lakes, and there are restrictions on agricultural practices in these areas.
“The Canterbury Regional Land and Water Plan implemented by ECan Commissioners provides a very strong planning framework throughout Canterbury to achieve reductions in discharges.”
The ECan report does identify a possible Clearwater Huts village septic tank leak as a factor that could affect water quality, as well as contributions from nearby Lake Camp.
But he found that Lake Camp’s contributions are likely low, with studies suggesting that nutrients were rising downstream of farmland, with more than half of total farmland nitrogen coming from runoff.
CDHB Medical Health Officer Ramon Pink said that for now, people should avoid Clearwater Lake and that animals, particularly dogs, should not be near the water.
“Exposure can cause rashes, nausea, stomach cramps, tingling and numbness around the mouth and fingertips.”
He said that no one should drink the lake water and that boiling the water will not remove the toxin.
Also, fish and shellfish can concentrate toxins, Pink said, so eating any fish caught in the lake should be avoided.
