The letter, sent to Bill English yesterday, has been signed by Central Otago Mayor Tim Cadogan, Waitaki Mayor Gary Kircher, Mackenzie Mayor Graham Smith, Southland Mayor Gary Tong, Clutha Mayor Bryan Cadogan and Gore Mayor Tracy Hicks.
It says the mayors are ''bending under the weight of problems being caused by irresponsible campers'', and receiving frequent complaints about ''the mess and waste left by this group of travellers''.
Often the complaints were accompanied by photographs of rubbish, bottles and, ''at times, human faeces'', the letter said.
The mayors want the Government to reconsider its stance on a tourist levy and are ''deeply concerned'' Finance Minister Steven Joyce and Tourism Minister Paula Bennett are against a levy.
Mr Cadogan said the main message of the letter was ''fund us''.
''No matter how we try to address the irresponsible camping issue, it all comes down to lack of funding for infrastructure.
''No matter what we do, we need money to do it.''
The mayors were grateful for government funding available through the Regional Mid-sized Tourism Facilities Grants Fund, but the money did not ''come close to matching the need in our and other popular districts''.
The letter said many of those complaining to councils about irresponsible camping wanted camping outside of motor camps to be banned, but that would be ''somewhere between impossible and impractical'', the mayors said.
New Zealand should not be afraid to impose a tourist levy that could help with infrastructure to tackle irresponsible camping, they said.
''New Zealand is a premium brand in the tourism market. We do not accept that our country is in a position where it needs to be afraid to impose a $20 levy (perhaps $10 on under-16s) to provide funding for the needs created by tourism in the regions . . . By not imposing a modest levy that will allow sufficient funding to provide suitable facilities in the regions, the Government truly risks killing the goose that is laying the golden egg.''
Mr Cadogan believed tourists would be happy to pay a small levy if it went towards improving facilities at freedom-camping areas.
A spokesman for the prime minister's office said the mayors' letter had been received, and the prime minister would respond ''in due course''.
The spokesman directed further queries to Tourism Minister Paula Bennett, who said the Government did have a role supporting councils with tourism infrastructure, especially those with a low ratepayer base and high visitor numbers.
''We've established the $12million Mid-sized Facilities Grant Fund and the first $3million round co-funded 14 infrastructure projects for councils around New Zealand. An additional $5.5million round has just closed and we're looking to fund another 20 or so projects from the strong response.''
Ms Bennett said although she had previously said the Government was not contemplating a tourism levy, ''we are currently looking at how else Government can support tourism infrastructure for those councils that are financially constrained''.
