How to clean up New Zealand's 7th most polluted lake. Made with funding from NZ On Air.
The death of Lake Horowhenua has been on the radar for decades.
It divides a community, figuratively and literally, as it creates a watery border between a town and countryside.
From a distance it resembles a picture perfect postcard, but up close the reality is very different.
Two hours north of Wellington, surrounded by rich alluvial plains and next to Levin, Lake Horowhenua is one of New Zealand's most polluted lakes.
Its catchment is tiny and so are the streams and drains flowing into it. Despite being small, they include the country's second and fourth most polluted waterways, Arawhata Stream and Patiki Stream.
The lake used to teem with fish and other seafood, which fed local iwi Muaūpoko who lived in the coastal forest that surrounded the water in pre-European times.
Weeds cover the lake in spring, before rotting and causing toxic algae bloom each summer.
Sediment swirls around the banks of Lake Horowhenua. Credit / Alexander Robertson
Swimming is discouraged year-round, and in summer, boating and kayaking are discouraged. Niwa freshwater scientist Max Gibbs shocked the district council in 2012 when he said the water was toxic enough to be lethal if swallowed by a small child.
A report card earlier this year put the lake at a 6.7, on a measure of 1-7 (seven being the worst). It looked at water clarity, chlorophyll content, phosphorus and nitrogen content.
But despite funding from local and national government, the clean-up is a long process slowed by lengthy court battles, objections from locals, fights over the lake's ownership and a few bureaucratic messes.
Resident Christine Moriarty is fighting to restore the health of the lake. She is frustrated at what she believes is a lack of action - or not the right action - from Horizons Regional Council, whose job it is to do something about it.
Horowhenua resident Christine Moriarity says a sediment trap system is taking focus away from the source of the lake contamination. Photo / Alexander Robertson
The council manages a vast swathe of the greater Manawatū-Whanganui region, including the land, air and waterways.
"The buck stops with the regional council," says Moriarty. "The regional council is not only not listening, but they have taken sides against us who are trying to get them to do the right thing. And now we are the bad guys.
"I'm always an optimistic person and I believe it's going to come right but it's going to take intervention by the Government to make some decisions about what farming practices happen in the country. We either fix it or we change the name to Lake Horror-whenua. It's a horror ride for the lake owners. Any other European land owner would be up in arms."
She highlighted some of the major causes of pollution, including stormwater runoff from nearby subdivisions and a drain within Levin's industrial area.
Horizons have made improvements around the lake, such as a $230,000 sediment trap, but Moriarty says it failed to address the source of contaminants.
"The sediment trap that the council has put at the south end of the lake is basically an ambulance at the bottom of the cliff.
"A stream starts as a spring and, in less than 2km, it becomes the second filthiest in the country. That should make it the easiest to clean," says Moriarty.
"Most streams are miles and miles long and you don't know where [the pollution] is coming in.
The Horizons Regional Council sediment trap was installed at a cost of $230,000. Photo / Alexander Robertson
"It is just common sense that if you are going to clean the water, you clean it before it comes into the waterways."
The lake is owned by the descendants of a small group of the Muaūpoko tribe, who set up the Lake Horowhenua Trust in 2013 to administer it.
It joined four parties in 2013 to form the Lake Horowhenua Accord which includes the Lake Horowhenua Domain Board, Horowhenua District Council, Horizons Regional Council, and the Department of Conservation.
Government has given the accord partners $2.36 million and the lake accord partners have contributed $1.7m. The money has gone towards sediment traps, a weed harvester, thousands of trees and kilometres of stream-lake fencing. An estimated $7m will be spent in the first decade of the accord programmes.
But the lake owners are divided and its trust recently reached an impasse with legal challenges and disagreement over who governed it.