The Waitaki District Council's planned erosion work at Oamaru's foreshore will "destroy'' the beach and could affect the colony of up to 500 little blue penguins near Oamaru Creek, an opponent to the plan says.
Lorraine Adams, of the informal Oamaru conservation group Coast Care, has lobbied for increased protection for the penguins north of Holmes Wharf since 1992.
She says the geotextile sand mattresses the council plans to install in front of a proposed 240m sea wall would change the nature of the existing beach and cause "unnecessary disruption'' for the birds.
"If it goes ahead it's going to be a mistake,'' she said.
Ms Adams has advocated for a less invasive approach to erosion protection and would like to see more rock armouring put in place - "the same as what they [the council] have done up the coast''.
"It's just a big mess,'' she said.
"We don't know how it is going to affect them [the penguins].''
However, Oamaru Blue Penguin Colony marine biologist Dr Philippa Agnew supported the erosion work at the waterfront and had suggested an expansion of the penguin colony be done at the same time.
The fence housing the 252 penguin nesting boxes would be pushed back 10m to allow for better spacing of the boxes, allowing the colony to keep growing.
Much of the original penguin refuge area had been lost to erosion over the past 15 years.
"The colonies continue to increase, and we have had to put in more boxes to accommodate those birds, but they're just kind of on top of each other at the moment,'' Dr Agnew said.
"It basically gives the birds somewhere safe to be without having them go, `Oh, this colony is obviously really crowded. I'm going to go and breed somewhere else' and run across the road somewhere and get squashed, or end up being underneath somebody's house.
"This allows us to try to encourage the birds to continue breeding there and reduce the spillover into other areas.''
She said the expansion would "take back'' the ground the colony lost in 2008 after a large expanse of beachfront disappeared during a large storm.
Erosion had been a problem at the colony before Dr Agnew started working with Oamaru's blue penguins in 2006 - in 2001 a large storm wiped out half the colony, she said.
"This has been an ongoing issue for a really long time. I really want to see something happen and I'm trying to work with council as best I can to support them.''
She understood the geotextile mattresses would allow the penguins better access to the nesting boxes.
The mattress coverings were like a "velcro'' covering.
"It will just be like a beach ... that's what I've been told.''
In a letter to the Otago Regional Council provided to the Otago Daily Times by Ms Adams, council consultants OCEL Consultants NZ Ltd write "the supply of sediment from the south is insufficient to replace the material swept north in the prevailing littoral drift by ocean swell predominantly from the southeast''.
The letter states erosion work in front of the penguin colony would be done "to stop further loss of the penguin reserve area''.
It adds the rock armouring used elsewhere along the coast cuts off direct access to the sea.
Council roading manager Michael Voss said the council was "getting the final consents sorted'', but he hoped work could begin this winter.
