The regional council has also served the contractor involved, Paul Smith Contracting, with an infringement notice for dumping the waste, some of which is still on site.
More enforcement action could follow; after another more recent complaint, staff found the Taylorville Rd was non-compliant and are investigating.
A barrage of other environmental complaints kept the council compliance team on the hop last month, but most complaints were unfounded.
A complaint about a dead cow near the mouth of the Mahinapua Creek checked out. The animal was confirmed dead in the water, but there was no access to the riverbed for a digger to move it.
Seven other complaints were effectively dismissed.
Compliance officers who investigated claims that a New River goldminer was muddying the water found the discharge was minor and was put right by the operator on the spot.
Two complaints about a Hou Hou goldminer also failed to fly: staff found the operator was compliant and there was no issue with his settlement ponds.
An allegation that a Haast firewood operator was dragging logs down a tributary of the Turnbull River was found to be groundless. Staff reported an old road beside the creek had been washed out and spread gravel along the creek area.
Complaints about gravel extraction at Canoe Creek, Barrytown, and earthworks at Kaniere and the lower Waitangitahuna River, Whataroa, also came to nothing, as investigation showed no rules had been breached.
The council is still looking into a complaint that non-cleanfill material was dumped on to a section at Karoro.
In other incidents, a Rotomanu dairy farmer has been ordered to stop letting his cows cross creeks in the Lake Brunner catchment area, in breach of a national regulation.
Also in Rotomanu, compliance staff found a dairy effluent pond overflowing on to land. The farmer escaped a fine because the effects were considered minor and he had taken "quick and comprehensive actions" to sort the problem.
An Atarau miner who spotted a turbidity problem, reported it himself and then fixed it, has not been penalised but investigations are ongoing.
The Grey District Council also featured on the brown list for May - an electrical fault with its sewerage pumps caused partially treated wastewater to flow into the Blaketown lagoon next to Sawyers Creek. The regional council is waiting for a report on how and why the fault happened.
