They are the least of the creatures that swim the Catawba River: baby fish, inches-long shad, eggs and larvae. More than 2 billion die in U.S. waterways each year, casualties of the nation's hunger for electricity.
Power plants need water as much as fish do. Water drawn from lakes or rivers condenses the steam that turns turbines. The rush of water traps small creatures against screened intakes or sucks them inside the plants themselves.
An Environmental Protection Agency plan to slow the death rate will affect hundreds of power plants nationwide and, in the Carolinas, eight Duke Energy and six Progress Energy plants.
Industry estimates say it would cost utilities and their customers up to $100 billion to retrofit the plants and save more fish, as environmental groups advocate.
But that might not be a tidy solution: the retrofits could leave less water for people.
The debate also refocuses attention on the electric industry's thirst for water, which competes with growing demand from cities.
Water experts predict more conflicts like the fight between the Carolinas over rights to the Catawba that went to the U.S. Supreme Court. The case was settled last year.
Most power plants return nearly all the cooling water they draw to rivers and lakes. Still, the scale of the plantsalso magnifies the amount that isn't returned to its source. For example, Duke's plants, companywide, pumped 3.9 trillion gallons last year. About 88 billion gallons evaporated as heated vapor - twice as much water as the city of Charlotte pumps in a year.
Models show that "for the next 30 to 50 years out, we don't really see a conflict between water use for humans and electric generation," said Tom Reeder, director of the N.C. Division of Water Resources. "My experience with the utilities is that they're looking for ways to conserve water and get the maximum use of their lakes."
But more frequent droughts, which climate models predict, could hasten that timeline.
"There is a high likelihood that water shortages and warmer water temperatures will limit power plant electricity production in many regions," including the Southeast, the U.S. Global Change Research Program reported in 2009.
Charlotte, for the first time, banned lawn watering during the deep drought of 2007 and 2008, the second to scorch the Carolinas in a decade. Duke largely shut off its hydroelectric plants to save water and reconfigured its McGuire nuclear plant to allow Lake Norman to be reduced 3 feet below its previous minimum.
The industry is researching new water-saving techniques, such as using treated sewage or farm runoff to cool power plants.
"The drought in the Southeast two years ago awakened a lot of companies," said Robert Goldstein of the industry-supported Electric Power Research Institute. "They thought (shortages) were a western problem."
EPA's cooling-water proposal, which will affect about 1,260 power plants and water-intensive industries, stems from a settlement last fall with New York state's Riverkeeper Inc. and other environmental groups. A public comment period ends in August, and EPA will take final action next July - and is not leaning toward the more expensive option that utilities fear.
The proposal is aimed at protecting the young or small fish killed when they're stuck against cooling water intake screens. Eggs or larvae are most often sucked inside the plant.
Despite the insignificant size of the fish, said Reed Super, a New York attorney representing the environmental groups, "this is the base of the aquatic food chain."
The groups say the best way to protect the animals is to make power plants recycle their cooling water in devices called cooling towers. The towers need only a fraction of the amount used by systems that discharge water after using it to cool their plants.
EPA has previously recognized their worth. The agency mandated cooling towers, or the technological equivalent, for new power plants in 2001. The agency's new proposal addresses existing plants. The option the agency prefers would not mandate cooling towers.
Duke's Catawba nuclear plant, which has cooling towers, draws 128 million gallons of water a day from Lake Wylie. The similar-size McGuire plant on Lake Norman, which does not have towers, pumps 2.6 billion gallons a day - 20 times as much.
But there's a catch - cooling towers save fish but consume more water.
Cooling towers evaporate nearly twice as much water as conventional systems, so the water isn't returned to its source. Catawba loses 25 percent of its water, McGuire less than 1 percent.
A group of municipal water systems in the Catawba basin that includes Duke, in comments to EPA last week, said requiring the towers on Duke's plants would leave cities and industries "exposed to greater risk of running out of water" during droughts.
EPRI, the industry research group, estimates that a nationwide EPA mandate for cooling towers would cost up to $1 billion for each plant. Environmental advocates say those estimates are overblown.
Catawba Riverkeeper David Merryman said the costs are a justifiable tradeoff for utilities' free use of a public resource, water, and the environmental damage they cause.
"It's asking them to account for their use of the water," he said.
Fish kill limits
EPA apparently won't force utilities to install cooling towers. But industry officials say utilities will struggle to meet other aspects of the proposal - including limits on how many fish they may kill.
Eric Myers, Duke's energy and environmental policy director, said the EPA's approach doesn't recognize differences among plant sites. Rather than mandating cooling towers, he said, it forces utilities to prove towers aren't needed.
That will mean laborious monitoring of intakes, including collecting fish stuck against intake screens, counting those that die and dumping live ones back into the lake, he said. Duke contends its plants aren't hurting fish populations.
"We think a pretty important indicator is the overall health of the water body, and that's something that's missing from the EPA rule," Myers said. "We should be focusing on species where we know have problems."
A cooling tower will serve the $1.8 billion addition to Duke's Cliffside power plant, now under construction about 50 miles west of Charlotte. Myers said the tower was included largely because the Broad River, its water supply, has less water than the Catawba.
Downstream, in the South Carolina portion of the Broad, the proposed Lee nuclear plant will sport cooling towers and a backup cooling-water reservoir. That's also to take pressure off the Broad when water levels are low during dry spells, Myers said.