In summer the water of Marton's Tutaenui Stream is diverted to supply humans and animals, and topped up with wastewater from sewage treatment ponds.
In winter its detention dams usually prevent flooding in the town, but they fill very fast and leave people on edge.
The almost total water take in summer was put in place decades ago. It wouldn't be allowed now under Horizons Regional Council's One Plan or the Resource Management Act.
Instead the life supporting capacity of the water would have to be protected, resident Greg Carlyon says.
He's a former Conservation Department and Horizons Regional Council staffer and co-ordinates the Tutaenui Stream Restoration Society.
He said the stream is a sad remnant of what it used to be.
The society has advocated to Rangitīkei District and Horizons Region councils for increased flow and wastewater improvements every year for five years, getting no more than a polite "thank you for your submission".
"For my part, it's when not if water is going to be returned to the stream. It's going to happen - it's just a case of being moderately patient," Carlyon said.
The Tutaenui's main tributaries are two smaller streams that drain fertile terraces and feed into the Marton reservoirs 10km from town.
The western stream, on the Smith farm, is fenced from stock and runs through bush. Its water quality is pretty good, Carlyon says.
The eastern one has had its meanders straightened and has road stormwater directed into it. It's not so great.
The water is held in two reservoirs built in the 1960s and 70s to supply the surrounding area. Pines have been logged from the lower reservoir, adding sediment and phosphorous to it.
The Rangitīkei council is considering adding carp as well, which Carlyon says would have dubious benefit.
Poor quality water from the lower dam is fed into the Marton Water Treatment Plant in Tutaenui Rd. The plant cost millions and can handle "just about anything".
It produces drinking water of human standard, that is used by both households and farms.
The water isn't metered and one cattlebeast can drink 70 litres a day.
"The relatively poor community of Marton pays for that."
From about November to May, little to nothing is allowed to flow over a large earth dam and become Tutaenui Stream.
From there to Marton many of the stream's banks have been fenced and planted, and people care about it.
The stream wriggles and meanders through and around Marton, but most houses have their backs to it. Service groups have made a walking track through town, but it's not well used.
In summer the empty stream is not very inviting. In winter its water can rise fast, and if its detention dams are overtopped it floods houses.
"Each year now there are two or three floods like that. The town is seriously at risk from floods that are going to become more frequent," Carlyon said.
Marton's wastewater treatment plant is typical of those built in the 1950s to 1970s and has not been maintained.
Its treated water is constantly discharged into the Tutaenui. In summer that can amount to putting 20 litres per second of sewerage into a river bed with just one litre per second of flowing water - overpowering it with nutrients, especially nitrogen.
"You can't hope to maintain its life supporting capacity like that."
Making matters worse, until 2017 "supertoxic" leachate from the Bonny Glen Landfill was treated with the wastewater, at the rate of three truckloads a day, and added to the stream.
This only happens in winter now, Rangitīkei senior wastewater engineer Arno Benadie said.
From there the stream flows seaward through mostly unfenced paddocks, with very little shade, to finish up in the Rangitīkei River.
By this time what water is left is growing streams of bright green algae, fed by nutrients from the wastewater.
There's long-term hope that treated wastewater will stop being added to the stream, except in winter when its flow can cope.
The council is considering merging the treatment of Marton and Bulls wastewater into a new facility that would discharge to land.
Rangitīkei iwi Ngā Wairiki Ngāti Apa joined the stream society in hoping this will happen.
"We're supportive of trying to restore as much flow as we can into the stream, and getting the sewerage out of it. That's looking fairly likely, but it could take some time," Chris Shenton said.
Another advance is replanting the land around the lower reservoir with locally sourced native plants.
Forestry New Zealand is contributing 17,000 this year, adding to others planted by landowners, volunteers and the society.
The society's popular 4km walkway around the reservoir, damaged by logging, could be reinstated through beautiful bush.
If water from an unused $800,000 council bore is pumped into the reservoirs to add to reserves more water could be allowed to spill out of the reservoirs and into the stream in summer.
An extra one or two litres per second would make a big difference.
If the stream could be maintained at two to five litres per second it would have eels, koura, pools, riffles and the highest aquatic values in the district.
Because it's close to the coast and has no fish barriers native fish would pass freely back and forth.
"It's got that potential to turn around," Carlyon said.