The spillway, which controls discharge from the Taieri River into the upper ponding area during floods, has been a hot topic since the gates were propped up by an unauthorised person after the regional council dropped them during floods in 2010.
Discussions between the farmers affected by the spillway and the regional council have been ongoing ever since.
Because there were concerns the concentration of spill from the southern end of the spillway could increase the risk of its failure and rapid uncontrolled discharge into the upper pond, the council was planning to adjust the top profile of the structure at a cost of less than $20,000 and ease the slope of the landward side.
It was also proposing to strengthen and buttress the spillway's landward slope with rock rip-rap to reduce the risk of scour failure.
This work, at a cost of $300,000, had been included in the long-term plan.
Environmental engineering and natural hazards director Gavin Palmer said at an engineering and hazards committee meeting this week farmers had expressed concerns about the timing of the work, funding for which was included in the 2011-2012 annual plan, and the impact a flood could have while work was being done.
As a result of that feedback, he was thinking about the timing and risk before making a decision on proceeding, he said.
"The work is around reducing the risk rather than increasing it. It is our intent to make it operate safely. It's not a huge change; more a fine-tuning."
The work involved mostly lowering the profile so it was, ideally, parallel with the surface of the water, and there were some concerns about that, he said.
"The new crest would be as strong as the present crest."
Upper Pond Ratepayers Group spokesman Simon Parks, who attended the meeting, said when contacted farmers did not have a problem with changing the profile of the spillway or the adjustments to its landward side but were concerned about lowering it and its timing.
"It's the worst time of year ... it floods in autumn and early winter."
The group was presented with three options and believed lifting the profile so it was consistent along the spillway was better than lowering it to do the same thing, as they were concerned it would mean extra water would end up in the upper pond.
"It could be a massive amount of water, which will take a long time to get out - the damage is done when we can't get the water out fast enough."
The "rationale just did not stack up", especially when they believed the undertaking given during the last annual plan process was that the work would not take place in the coming year, he said.
They were now waiting for the regional council to come back to the group, Mr Parks said.
