In 2002, oxygen levels that could support fish along the entire length were recorded for the first time since industry began on the Mersey.
Besides, the ability of a waterway to support fish is a pretty simple and dramatic barometer of its health.
The state reported last week that more than a quarter of the lakes in the Adirondacks were too acidic to support fish.
Consequently, the lake may remain with a negative K and be unable to support fish for many years.
Because of acid rain, this Scandinavian lake is now too acid to support fish.
In some spots, the river is covered with soap foam and lacks the oxygen to support fish.
"And with this, the river would once again be able to support fish, or water life."
The total force needed to support tub, water, AND fish together remains the same.
The salt marshes, so important to the ecosystem, could not support deep-water fish.
However, due to environmental regulation the water quality is now improving and the river supports fish, including trout.