Water temperatures have climbed to 26.7°C—well into the range where dissolved…

June 29, 2026Southern Limestone/Dolomite Valleys and Low Rolling Hills

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Water temperatures have climbed to 26.7°C—well into the range where dissolved oxygen becomes scarce—and stream flow has slowed to a barely perceptible trickle. That combination is catastrophic for the endemic mussels of the Cahaba: they are sessile filter-feeders dependent on a steady supply of oxygen-rich water moving past them, and in warm, stagnant conditions the water column degrades faster than they can survive.

The reach is already on the federal impaired list, and multiple stretches of the Cahaba within the surrounding area carry the same designation. These endemic mussels—found nowhere else on Earth—have survived here for millennia through patterns of flow and temperature we are now routinely breaking. Each summer like this narrows the margin further.

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