Dairying meets Abrupt Climate Change in rural Canterbury

My rage, shame and grief knows no bounds as I share this.

I remember what used to be a pristine little lake at Little River on Banks Peninsular,east of Christchurch (our friends lived across the road), from my childhood.

I know people (mostly in high places), who should be frogmarched down to this lake and have their heads rubbed in it. 

Criminal arseholes!

Canterbury's poisonous Lake Forsyth kills sheep, full of green slime

Poisonous water in a Canterbury lake has killed sheep and household pets, after recurring algal blooms made the water toxic.

STACY SQUIRES/FAIRFAX NZ   Lake Forsyth on the Banks Peninsula is green with toxic slime.

Stuff,

26 November, 2014

Locals say that after several years of improvement, the water in Lake Forsyth on the Banks Peninsula has deteriorated after a run of dry weather.

For the last few months, large parts of the lake have been green, with toxic green slime seeping onto its shores.

Signs warn that the water is dangerous for humans and animals.

Several weeks ago, a farmer lost around 30 sheep after they died drinking water from the lake.

"It's in a very bad state this year, which is actually quite surprising. The quality of the lake has been improving for the last five years,"  said Banks Peninsula zone committee chair Steve Lowndes.

"This year, it's gone backwards."

STACY SQUIRES/FAIRFAX NZ

The green slime washes up on the shore.

He had lost a cat and a dog because of the lake's water over the years, he said.

While there was signage declaring the water unsafe, visiting campers may miss the warnings, he said.

"It's toxic. It kills people's pets, and if humans get into it, they can be made to feel very sick... as it is, it's a health hazard."

"With climate change and sea level rise and all sorts of things, you have to think the lake is in trouble."

ECAN/SUPPLIED  Cows in the Okana River, where banks have eroded into the water. The river forms the Takiritawai River and flows into the lake.

The state of Lake Forsyth shows the difficulty of revitalising some of Canterbury's unhealthy lakes, which has been the focus of Environment Canterbury (ECan+) and other community groups in recent years.

The larger and more high-profile lake nearby, Lake Ellesmere, is undergoing its own recovery expected to take generations.

Lowndes said the zone committee had tried to improve Lake Forsyth's quality – it wanted to create a sediment trap and wetlands at the mouth of the lake – but acknowledged it may never recover.

The main culprit was the phosphorous-rich soil on the bed of the shallow, brackish lake. Erosion of nearby river banks had caused further soil to enter the water, creating an ideal environment for toxic algae.

Blooms occurred routinely, but the latest bloom was particularly severe.

A public health warning issued in January, which warned that blooms of blue-green algae posed a risk to both animals and humans, is still in place.

STACY SQUIRES/FAIRFAX NZ  Signs on the lake-front warn visitors and their pets not to go near the water.

ECan surface water science manager Tim Davie said the regional council had been working with the Wairewa runanga to improve the lake's water quality.

It did so by maintaining high water levels, which allowed plants to grow, he said.

"[T]his year the very dry spring meant that the lake has remained low, aquatic plants did not grow well in the lake and we have a seen a severe cyanobacterial bloom," he said.

The Wairewa sub-regional plan, which had hearings last week, would introduce new policies and rules to reduce sediment going into the lake, he said.

They included rules around fencing-off stock from rivers and streams to reduce bank erosion, and introducing minimum flows in nearby rivers.

Trophic level index scores, used to measure the health of lakes, show a trend of improved quality in the lake in the last five years. 

Latest testing, however, shows it had dipped from previous years.

Iwi Ngai Tahu has customary title over the lake, meaning only members of the iwi can fish for tuna (eel), recognising the lake's importance as a food source to local Maori.

Forsyth is one of two customary lakes in New Zealand, and the only one in the South Island. 

The Wairewa rununga is actively involved in managing the lake. It was unable to comment on Tuesday.