The churning rapids of the White Nile near the Kalagala Falls can be heard from afar - a dull roar, punctuated by excited shouts of rafting tourists navigating the rushing waters with the help of local guides.

The spot in a rural area near the central Ugandan city of Jinja reveals a wide expanse of the frothing river surrounded by lush vegetation. This area is supposed to be protected - but it's currently under threat by the Isimba Dam, under construction about 40 kilometers (25 miles) to the north.

In Uganda, the government wants to use the force of the White Nile, a tributary of the main river, for hydroelectric dams. This could increase access to electricity for the 85 percent of Ugandans who lack a connection to the electrical grid. But it could also mean environmental risks and an end to lucrative business for locals around the dam sites.

Ecosystems affected

The current dam proposal would generate 183 megawatts, and create a reservoir that would flood the area around the Kalagala Falls, submerging the rapids and much of the surrounding forest.

Lori Pottinger, the Senior Africa Campaigner for environmental group International Rivers, says the hydroelectric dam would alter the natural ebb and flow of the water, risking the delicate balance of the river ecosystem and throwing the lifecycles of plants and animals off-kilter.

Pottinger says that translates into a loss of biodiversity. International Rivers has also been campaigning against the proposed Isimba Dam since the area to be flooded includes nesting grounds for Uganda's national bird - the crested crane - which is also an endangered species.

Warnings from the past

It's not the first time locals are facing the impacts of dams. The Bujagali Dam, built upstream in 2012, flooded another famous site for rapids: the Bujagali Falls.

Alex Muzungu, a local rafting company tour guide, recalls the harsh economic impact on the local community, which depended on the thousands of tourists who came to raft or kayak in the area.

"Since they built that dam, all the rapids changed and we ended up losing a lot of people who used to come," he said - including staying in local hotels, and eating and shopping at local establishments.

Tourists do still come, and he guides them over the remaining rapids, still considered some of the best in the world - even if they are not as good as they were before.

Energy vs. ecotourism?

The local and international uproar over the environmental and economic consequences of the effects of the Bujagali Dam pushed the Ugandan government to sign an indemnity agreement with the World Bank, promising to protect the Kalagala Falls area from the consequences of dam projects.

But despite that, the government is pressing ahead with construction plans, claiming the new dam will expand access to electricity for people in the region. According recent World Bank figures, fewer than 15 percent of Ugandans have access to electricity, and the power that is available is too expensive for most to be able to afford it.

Ugandan Energy Ministry spokesman Bukenya Motovo says the government is aware of the negative effects of dam projects. But he points out: "Uganda doesn't have enough energy to drive its economic development programs."

Motovo says that rafting and kayaking will continue at other sites in Uganda - but that there are only a few locations suitable for hydroelectric dams. And he is convinced this is Uganda's best option for relatively low-cost energy.

"Hydropower is clean energy, green energy," Motovo says. "We try as much as possible to minimize the impacts or even manage those impacts."

Even though tourism brings in more foreign currency than any other industry, he says ecotourism and adventure tourism don't bring in enough revenue to offset energy gains from the dam projects.

Ugandan electricity minster Motovo acknowledges a conflict. "Do we sacrifice energy for tourism? Or, do we sacrifice tourism for energy?"

Balancing the benefits

And some local businesses have benefited from the hydroelectric dams. On the outskirts of Jinja, the sprawling industrial complex of Steel Rolling Mills used to have to schedule operations around regular power outages.

Electrical Manager Kolumbi Charles says after the Bujagali Dam was completed, they were able to stay open 24 hours a day instead of eight, and add a new scrap metal recycling facility. He says those changes doubled employment, and created job opportunities for locals who collected the scrap metal from the area and brought it to the factory.

But Charles does worry about the balance between the quest for more energy and the environmental risks. "We have foregone our falls, several of them, in the name of generating power. The question is: for how long should this continue?"

Dam under construction

Charles feels confident the Ugandan government will strike that balance. But environmentalists like Pottinger are not as convinced. She says the Ugandan government isn't adequately weighing questions about cumulative impacts.

So far, the Ugandan government has not publicly released an assessment of the environmental impacts of the Isimba dam project.

And the World Bank has expressed concern to the Ugandan government over potential violation of the indemnity agreement.

But with construction on the dam already underway, it seems the roaring rapids near the Kalagala Falls will soon be submerged. But activists and local tourism companies have not given up, and are pushing the government to build a smaller version of the dam that they hope will reduce regional impacts.