Madison Dam area

Madison Dam

I have been asked many times about the status of Tubifex below Ennis Lake. Most people suspected large Tubifex numbers here. I did not. In Montana, Tubifex appears to always be depressed below lakes. Ennis Lake is much more like a lake than a deep storage reservoir. In mid-October 1996, I finally took samples from above (274) and from below (275) Madison (Ennis) Dam. Among 111 worms examined from above the dam, only 1 might be Tubifex. From below the dam I examined 106 worms and none were Tubifex. Worm density was only medium at both sites. As always, I selected worms for slide mounting to emphasize Tubifex.

If TAMs do not come through Ennis Lake, I suspect that Tubifex numbers must limit the disease here. At least I hope that it does! This should be another good area to try to calibrate Tubifex numbers with disease severity. Tubifex here likely varies each year depending on flow and temperature.

Aquatic Oligochaete species list

5 JAN 1997, updated on 28 JAN 1997 D.L. Gustafson
Back to the Madison River Tubifex Summary
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dlg@rivers.oscs.montana.edu