Most British Columbians know well the names of the manmade behemoths that straddle their rivers and produce hydroelectricity: the W.A.C. Bennett, Keenleyside, Mica and Revelstoke dams.

There are many more but they're less obtrusive, less gargantuan.

Those massive dams were all built under varying degrees of controversy, blocking rivers and creating reservoirs, sometimes forcing the relocation of communities.

Still, most British Columbians have preferred hydro power to the alternatives -- nuclear power, or coal, or natural gas.

But the NDP wants voters to think about the latest alternative -- and turn it down flat.

The BC Liberals have been promoting run-of-the-river projects as a green alternative to more power mega projects.

It's part of the party's ambitious green agenda to cut greenhouse gas emissions and get more independent power producers sending energy to the B.C. Hydro grid.

The NDP wants a moratorium on run-of-the-river power projects. Leader Carole James has accused the Liberals of selling off the province's rivers and says there hasn't been enough public consultation on the projects.

"There are places where it may make sense, to look at run of river projects. There are areas in the province where it may make perfect sense and it may be good, green energy," she said on the campaign trail.

"But. . . they're saying the water and the electricity will belong to the private company, not to British Columbians. Well, that's a public resource and it belongs to us in this province and it needs to stay in public hands in this province."

Steve Davis, president of the Independent Power Producers Assoc. of B.C., said James is wrong.

"The water belongs in all projects to citizens," he says.

"All that happens is that the (independent power project) gets a licence, gets permission to divert a portion of water to a pipe, to a powerhouse and back to the creek. We rent that water and return it."

James and some environmental groups also worry about the "cumulative" effect of several projects in one area.

"They're looked at individually. We've said that makes no sense. You need to make sure you look at the cumulative impact of all of those projects to ensure that we've really taken a look at the environment and how it's going to be impacted."

Davis's association represents more than 320 companies who produce power through run-of-the-river projects or by burning wood waste or natural gas.

The companies have been around for 18 years, including when about half of the current 47 projects now in operation were approved under an NDP regime.

Environment Minister Barry Penner said since 2001, the government has issued 61 water licences for run-of-the-river power generation, and rejected or withdrawn 154.

Some are now under construction and some are still under review.

The average size of a run-of-the-river project is about 10 megawatts, said Davis, enough to power 6,000 homes for a year.

By contrast, the proposed Site C dam on the Peace River in northeastern B.C. would produce about 900 megawatts annuallyThe W.A.C. Bennett dam is capable of generating 2,730 megawatts at peak capacity.

Melissa Davis, of Citizens for Public Power, and Craig Orr, a spokesman for Watershed Watch, share James's reservations about run-of-the-river.

"We're not opposed in principle to run-of-the river projects but we have concerns about environmental impacts, particularly the cumulative environmental impacts associated with multiple run-of-river projects," Davis said.

She said there needs to be proper public and environmental oversight.

She cites the proposed Bute Inlet project and one under construction at Toba Inlet, located about 200 kilometres northwest of Vancouver.

Bute would be massive and far from the mom-and-pop projects that many British Columbians now envision. It's actually more on scale with Site C, she said.

Bute would come in at more than 1,000 megawatts annually while Site C is about 900. Toba is slated to produce about 200 megawatts.

Orr, of Watershed Watch, said some of the newer proposals are "anything but small, green, micro-hydro projects and the impacts on fish and wildlife are a concern."

He even suggested another massive dam might be better.

"Why can't we have that dialogue? British Columbians are not being allowed to even consider the question: `Do we want one Site C dam on the Peace River or do we want 600 private power projects scattered all over B.C.?"'

Penner and Davis both point out that B.C. has been a net importer of electricity for seven of the last eight years, but critics point out the province has also been trading electricity with California for about the past four decades.

California recently introduced green legislation that will affect -- but not kill -- the export of power from B.C. Hydro, the Crown corporation which buys all the power produced in B.C. by the run-of-river projects.

Despite the B.C. Liberal government's insistence that the run-of-river model is a source of green energy, earlier this month, the California senate rejected efforts by electrical utilities to allow power from sources such B.C.'s run-of-river projects as renewable energy.

Legislation obligates California to source 33 per cent of retail electricity sales from renewable sources by 2020.

But the senate has disqualified hydro projects projects producing more than 30 megawatts. Projects that are bigger aren't considered renewable.

Penner notes that if the run-of-river power passes the senate's scrutiny for renewable it will fetch a higher price, but even if it doesn't, B.C. can still sell the power to California.

Penner sent a letter to the California legislators earlier this month pointing out that river projects undergo stringent environmental assessments.

An advisor to California Gov. Arnold Schwarzenegger has said recently that B.C. run-of-river power may yet qualify as green power.

The bill is being reviewed by the California state assembly and a decision is months off but NDP leader James is asking B.C. voters to make their own decision on May 12, when they go to the polls.