Dams don’t release CO2, they can produce trivial amounts of methane but that breaks down fairly rapidly in the atmosphere. It’s only when vast amounts of methane are released at the same time or the source is continuous that methane is an issue.
In terms of fish, large dams are needed for flood control and water. But rivers and streams often have huge numbers of small dams that are equally problematic and far less useful.
In terms of fish, large dams are needed for flood control and water. But rivers and streams often have huge numbers of small dams that are equally problematic and far less useful.