Sheep guts, test tubes and a fridge were among items of rubbish illegally dumped in the Bay of Plenty in the past year.
Bay of Plenty Regional Council pollution prevention team leader Stephen Mellor said the regional council had dealt with 96 instances of illegally dumped rubbish in the past 12 months.
Items included sheep guts in a Katikati stream, test tubes washed up on the beach in Tauranga, a fridge in a river at Welcome Bay and couches on a beach in Papamoa.
Mr Mellor said it was difficult to gather evidence to prove the origin of dumped waste, particularly for small scale "fly-tipping".
The council had not had any success in finding the people responsible over the past 12 months.
"Waste is often dumped in areas with little foot or vehicle traffic to reduce the chance of anybody witnessing it happening," said Mr Mellor.
However, the regional council had taken prosecution cases for illegally dumped rubbish in the past few years where it had good information on large scale operations.
The regional council dealt with illegally dumped rubbish left in locations which fell under its responsibility such as waterways.
Tauranga City Council chief executive's group general manager Kirsty Downey said there were 278 reports of illegally dumped rubbish in the 12 months to the end of April. The council received about another 1300 general litter notifications.
Locations of the rubbish ranged across the whole city.
Ms Downey said only a small percentage of offenders had been identified in the past 12 months. There were five written warnings issued in the past 12 months.
Warnings were for first time offenders, issued with education to prevent re-offending.
There were 441 cases of illegally dumped rubbish recorded in the Western Bay of Plenty district in the 12 months to the beginning of April, according to council group manager customer and community services Kevin Jefferies.
Some of the district's most common dumping spots were Te Matai Rd, where rubbish had been dumped 30 times over the 12 month period, and Old Coach Rd, with 14 cases of dumping.
Mr Jefferies said no one had been caught in the act of dumping rubbish in the past 12 months. However, council staff and contractors went through the dumped rubbish and bags and retrieved any information linking people to specific dumping incidents.
He said six cases were followed up where those who dumped the rubbish were identified and fined.
Envirohub Bay of Plenty chairwoman Mary Dillon said toxic rubbish getting into streams could be an issue.
Farm waste could also get into aquifers if farmers were careless about rubbish they buried.