The council had become increasingly aware of issues surrounding the four permitted horse-use beaches in Dunedin, Waikouaiti, Tomahawk, Smails and Island Park, Ms Gordon said.
Horse trainers thought they did not have to clean up their horses' dung, she said.
"If dog owners don't pick up their poo, everyone is up in arms about it. But they think a horse can poo and it's OK. It's not OK.
"Leaving horse faeces on the beach is littering and an offence under the bylaw."
Ms Gordon said the dung was very noticeable at low tide.
"There is just poo everywhere. It's really not pleasant."
Catching offenders was the difficult part.
Dung usually got washed away, but there had been problems with people sweeping it out of horse floats on to the reserve, away from water.
Training horses on a beach also prompted safety concerns, Ms Gordon said.
"Who knows what an out-of-control horse can do to its rider and anyone else in the way."
The council had no plans to change the bylaw, but "when it is up for review, who knows what submissions we will receive".
The bylaws could change at any time and it would depend on the submissions made, she said.
Waikouaiti beach trainer Andrew Faulks said there was no problem with horse dung at Waikouaiti and preventing beach training would adversely affect local horse trainers who collectively ran about 60 horses along the beach.
Smails Beach trainer Jack Gamble said the four horse trainers who used Smails Beach kept it very clean.
Mr Gamble believed issues lay with "hoons with 4WDs".
Ms Gordon said the council had put chains and gates around Ocean View and Smails Beaches to keep "idiots off the sensitive dunes", but Mr Gamble said there were still some "clowns" around, some of whom recently removed a "heavy steel gate" at Smails Beach and proceeded to tear up the sand.
Ms Gordon said there were also problems at Ocean View Beach, where the remaining track to the beach was just big enough to get quad bikes through and the council continued to catch offenders.
