The Department of Conservation has admitted that dropping 1080 bait on a Marlborough Sounds tramping track last year was unacceptable.
The DoC review has looked into the incident where bait accidentally fell onto the Nydia Track, which was excluded from the aerial bait distribution under a Medical Officer of Health condition for the operation.
Bait fell near some people on the track and the review has found they should not have been allowed on the track at the time.
DoC conservation services director Mike Slater said the department had received a formal warning from the Nelson Marlborough public health service and admits the mistake was unacceptable.
Mr Slater said the review has recommended several improvements to the department's 1080 drops in the future.