Council director environmental monitoring Scott MacLean made that point in an update report to be tabled at the council's regulatory committee meeting today.
There was ''no known control tool'' for didymo in the world and very little research had been undertaken on the invasive alga and its potential impacts, Mr MacLean said.
Since the New Zealand incursion and extensive research undertaken here, this country was now considered ''the global authority on didymo''.
In Otago, didymo was ''reasonably widespread'' but the rate of spread through human activity had ''slowed significantly'' since the ''Check, Clean, Dry'' (CCD) programme, involving boats and equipment, had been implemented.
The ORC employed a CCD advocate each summer, on a cost recovery arrangement with central government, to move between high use recreational aquatic locations, such as rivers and lakes, informing people of the CCD programme and its importance.
The ORC also spread the CCD message at events such as jet-boat racing and multisport events, and event organisers were given information they could give out and advised how they could set up wash stations for boats.
''This social marketing has been crucial in slowing the spread of didymo throughout Otago,'' Mr MacLean said
The CCD programme remained successful, and didymo had not been recorded in the North Island and the spread had slowed in South Island areas where it was originally detected, he said.
