Volunteers with the Ottawa Riverkeeper were out on Kettle Island again this year for the annual garbage cleanup, but this time they were worrying about the National Capital Commission's desire to build a bridge across the island, and what that might mean for habitat there.

"We've been here last year, and we removed four tonnes of garbage — big burnt car, 30 tires and more," said Andrew Mott, one of the volunteers.

However, the NCC recently named the island as its preferred choice for a bridge across the Ottawa River between Gatineau, Que., and Ottawa's east end.

"The salamanders and … little snakes would probably be killed off eventually, and the construction of the bridge would do a lot of damage to their habitat too — but then we have to decide if we need a bridge, don't we," Mott said.

Conservationists are focusing their attention on Kettle Island because of the bridge proposal, but they say plants, animals, and fish are feeling the pressures of urbanization all up and down the Ottawa River watershed.

They are also studying the effects on small tributaries, such as Sawmill Creek, which winds through the south end of Ottawa, emptying into the Rideau River, which then flows into the Ottawa.

They want to see how property development pressures are affecting them.

"We're looking at changes in bank stability, we're looking at sources of pollution. So, if we see something running into the creek we're looking at sediment coming in, or if there's a lot of garbage," said Julia Sutton, of the Rideau Valley Conservation Authority.

"Creeks like this are very important because [they provide] habitat for species that support other species in the Ottawa River," she said.

Kettle Island is important to the river's health too. The island is one of the biggest on the entire river, about four kilometres long and a kilometre wide. It includes mature forests and wetlands.

The Riverkeeper volunteers believe a bridge would be a disaster for the island.

"There are other spots that would have less impact on the river. I'm not talking about the people's backyards, I'm talking about health of the river," said Laurel Rosene, one of the volunteers.

The NCC's consultant, Steve Taylor, is recommending that the bridge cross only the western tip of the island, where, he says, the impact would be minimal.

"There's no consideration for off-ramps. The bridge itself will be over 20 metres in the air, and it will just be the piers that have an impact on the island itself," Taylor said.