TORONTO - Legislation to protect Great Lakes water from being siphoned to jurisdictions not immediately surrounding the lakes is being finalized by Ontario, Quebec and eight U.S. states.

Still, environmental advocates warn that the Great Lakes-St. Lawrence River Basin Sustainable Water Resources Agreement benefits developers rather than the public and isn't tough enough in key areas.

Intra-basin diversions, the legal transfer of Great Lakes water as long as it stays within the Great Lakes Basin, are not adequately addressed in the agreement, said Robert Wright, a lawyer with the Sierra Legal Defence Fund.

"The bar should be a very high one and exceptions really should be exceptional situations," Wright said. "We'd like to see if we can ratchet down those exceptions even further than they already are."

In a written submission to the Ontario government, Sierra argued that intra-basin transfers should only be allowed when there is an equal return flow of water to the original source.

There's been little research on the possible negative effects of large transfers in the Great Lakes Basin, and Environment Canada forecasts a one to 1.5-metre drop in water levels for some of the Great Lakes over the next 50 years due to climate change.

Those factors combined means there's no margin for error when it comes to water levels in the Great Lakes, Wright said.

"With longer growing seasons and more frequent drought events due to climate change, more and more users will want access to Great Lakes waters," Sierra's submission reads.

"Intra-basin transfers will add to these pressures and we simply do not know the cumulative impacts they will have."

The Great Lakes-St. Lawrence River Basin Sustainable Water Resources Agreement was signed in December 2005 by Ontario, Quebec, Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania and Wisconsin.

Each jurisdiction is now preparing legislation to finalize the agreement.

Concern about the potential for intra-basin diversions is also being voiced by the citizens group the Georgian Bay Association.

Group spokeswoman Mary Muter said she fears the first big transfer will open the floodgates for other proposals and, inevitably, developers will pressure the government for more and more.

"This is big-time development pressure pushing for this and we're a bunch of environmental organizations - what takes priority when an election's coming up?" Muter said.

The group has also said an endorsement in Canada of large water diversions could have a trickle effect in the United States.

"We are concerned ... it will create a precedent for the U.S. states involved to not require return flow and could allow extremely large transfers, for which we know there is a very high demand," the group wrote to the government.

Ontario is still working on the specifics it wants in its legislation, but Minister of Natural Resources David Ramsay said he doesn't believe intra-basin transfers need to be outlawed.

"Only in small quantities will we allow intra-basin transfers without return flow - much larger ones we insist on return flow - and we want that flexibility ... so we can have sustainable development," Ramsay said.

"We'll only do it where it is sustainable and the quality of the water does not get abused."

The provinces and states will keep each other accountable and there's a feeling of confidence that everyone has the lakes' best interests in mind, Ramsay said.

"Having that wonderful supply of fresh water for our industries is a great competitive advantage for all these jurisdictions, so it's certainly in our interests to protect the quantity (of water) in the Great Lakes as well as the quality," he said.

"We're all watching each other and that's how we're going to keep it honest."

Gord Miller, Ontario's environmental commissioner, said it's important the province gets its legislation right because any flagrant abuses of the lakes could lead to a breakdown of the whole deal.

"It's a very sensitive time and we have to be careful of how any actions we take are perceived - not just domestically but by the Americans - because if we take any latitude with some of these interpretations the consequences could be substantial," Miller said.

Ontario's actions will be scrutinized by those in the U.S. who oppose the agreement, and if the deal stalls in the American legislatures "you could lose the whole agreement," he warned.

"Then it could degrade into a free for all, because without this agreement, you can get ... water moving out of the basin into the Mississippi basin and beyond."