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Management by the Control
Enemies of Waterfowl
4 other sections not shown
abundance acid waters acres alkaline aquatic plants auxiliary spillway birds blue-winged teal bulrush burreed bushy pondweed cattail chemical chufa Common threesquare construction crop depth dike draw-down duck foods duckpotato duckweed effective F. M. Uhler feet Figure Fish and Wildlife flood flow flowage fresh-water gallons growing season growth habitat heavy hoops impoundment inches instances Ladysthumb Lake located Muskgrass muskrats National Wildlife Refuge nesting Nymphaea Patuxent Research Refuge Photograph by F. M. poison pond pond waters ponds and marshes pondweed Potamogeton runoff Sagittaria platyphylla sago pondweed salt marsh Scirpus seed seepage shallow slope Small duckweed small ponds smartweed sodium arsenite southern Spatterdock species spikerush spillway spray stained stream suitable surface surface runoff tion tubers turbid U. S. Fish U. S. Soil Conservation usually vegetation water control structure water level water supply waterchestnut waterfowl waterfowl habitat waterlily watershield wave action Wigeongrass wild millet Wildcelery Wildlife Service wildrice winter wood ducks