The covers are made of buoyant white sheeting by Flamingo Plus (2000). They come in modules sized to fit almost any farm dugout, and work by stopping sunlight at the surface. This blocks growth of algae and weeds, and limits evaporation and water warming. Evaporation control further boosts water quality, because evaporation concentrates all contaminants present. In hot years, even full dugouts can lose up to half of their water volume this way.
The idea of using covers to improve water quality and conserve supplies is not new, but Flamingo's approach may offer an affordable and durable design. In trials which took place last year, 100 percent of the water was covered in a dugout with chronically poor water. As a result of the cover, the dugout was maintained virtually free of algae. For a dugout with better water, 75-80 percent coverage produced good results.

A mid-season test of a 50 percent cover aimed at evaporation control gave unexpected quality improvements, according to test participants. Even this partial coverage so calmed waves caused by wind that suspended solids settled, and the need for inhouse filter maintenance fell sharply. A 25 percent cover of modified design aimed at reducing costs for larger dugouts did not help water quality.

PFRA built two identical lined dugouts so both evaporation and evaporation control with covers could be tested. It was found that standard `lake' evaporation estimates understate water losses, especially on days when these are high. Evaporation control efficiency, on the other hand, topped 80 percent with 77 percent of a test dugout covered.

Flamingo is aiming for an average cover life of six years or more. Test covers have repeatedly survived winds up to 80 kph. Less is known about the ability to resist damage from ice when water levels are drawn down through the winter, or resurge with spring runoff. Results this spring at the five 1993 test sites will be instructive.