WeitiBay chief executive Evan Williams said he and his team were working hard to minimise the sediment flow and were meeting all the standards they had to.
Townend said there were a number of development sites from which sediment was flowing, and it was threatening the wildlife and habitats in their reserve.
He has since gone out whenever he can during a storm or rain event to take sediment samples from the sites he had access to.
One of the main problems was that Auckland City Council could not pinpoint whose site the sediment came from as it would flow from multiple sites into one catchment.
But Townend has access to two areas that are owned by only one developer, and has been taking samples for a report on the issue. The draft report has already been given to council.
There needed to be a change to the way consents were given for development, he said.
"Developers talk in percentages," he said.
This meant if a developer spoke of retaining 90 or 95 per cent of the sediment from their sites, it did not show if the leftover five or so per cent could be five grams per cubic metre, or 5000 tonnes of sediment.
The group is currently battling the matter in court, a process which Townend said was a "very expensive game to play".
In the meantime, the reserve is getting "a right raw kicking".
"The simple thing is development should happen with regard to the impact it's going to have on the sensitive environments that are around it."
Sediment discharge should only be allowed in small amounts that would not harm the marine environment.
Townend said the "tool box" developers had to deal with sediment was "enormous".
Everybody likes to say it's only the construction work, but it isn't. That's just an important point if we're all being fair.
"It's all available to them but it costs money.
"Think about the amount of sediment control they are putting in place in Transmission Gully down in Wellington."
Townend said people did not know what they were missing. They had not come down to swim in the estuary amount the bioluminescent plankton at night, or seen the fish or birdlife.
"We've got to take better care of it, eh? That's what we're trying to do."
He felt the majority of councillors wanted to "do better in this area" but there was no case law to support fining companies.
The society has a Givealittle page to help with its legal costs.
Williams said there was a natural slip that caused a large deal of sediment flow in June, but this was out of the company's control. He believed much of the photography used by the society was of sediment caused by this natural slip.
"We work really hard at making sure that we put as many controls in place as possible and we have taken a lot more steps to do that than we're obligated to under the rules, so we're actually working hard at it and we care about it."
Over summer Auckland received more rain than it usually would in a year, which tested all the developers' systems to their maximum points, he said.
The sediment that came off his site included natural run-off, he said. There was a pine forest there before his company bought the site and as the harvest area settled down it was producing a large amount of run-off "which we simply can't control".
"Everybody likes to say it's only the construction work, but it isn't. That's just an important point if we're all being fair."
He said WeitiBay was not the only source of sediment in the area.
"There are a lot of people, some of whom are working hard and some aren't. I can tell you we are working hard at it. We get audited every time there's a big rain event.
"We're meeting all the standards we're required to meet. People may argue those standards aren't good enough but at the moment they're the standards that apply through the whole of Auckland . . . we think they're reasonably tight."
