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Methods & equipment

Drawdown

Drawdown is the deliberate lowering of pond or reservoir water levels in fall or winter to expose submerged vegetation, tubers, and shoreline plants to freezing temperatures, dehydration, and freeze-thaw damage. In northern US climates with sustained sub-freezing winters, drawdown can kill 60–90% of biomass over a single season. Effectively free if outflow control exists. Useless in Florida and the Gulf Coast — winters are not cold enough for sustained killing temperatures. Requires permits in most states because of fish stress and downstream water-quality impact.

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