Red Line in the Water – Lake Divider Curtain

By: Michael Curry, Co-Designer of Limno Corrals

The Limno Corral System evolved in providing design options with a range of diameters and shapes. These designs assisted the researcher’s need for a specific volume of water required for testing. The common floatation shapes provided are Pentagon, Hexagon, Octagon and Decagon with sleeve depth ranging 0.5 – 20m deep.

When our Limno Corral Systems were introduced for freshwater research, another opportunity was presented. A research group had to replace a decommission hydro barrier due to fabric degradation. We were asked to make a new barrier improving the design. The researchers provided a sample of the old barrier fabric for our reference and a list of improvements needed.
The barrier’s weight had to be reduced, easy to handle in forest, easier to assemble with no zippers, the floatation needed to be less cumbersome, required an anchor skirt and the bottom edge must match the contour of sediment.
We had never made one before and with a “can do attitude” proceeded to make it better.
The curtain length is needed to divide a lake 110m wide with varying depths from 0.5 – 4m. The measurements provided were enough to start designing and planning of the fabrication.
The material we chose was a softer PVC Coated nylon weave with marine grade UV treatment. The choice of this material helped with handling the curtain on the shoreline during deployment.

The weight reduction enabled the fabrication of the floatation pocket and trimming of the bottom edge to match the lake sediment curves exactly for the length of 110m.
We embedded below the floatation pocket a fiber cable one tenth the weight and the same strength as the steel cable used before. The final improvement was the use of six-inch diameter polyfoam ten feet long separate from the floatation.
We designed gill openings in the floatation pocket to accept the polyfoam continuously for the 110m length.
Once all the components were carried to a small area on shoreline the assembly proceeded. With many helpers, the deployment was successfully anchored in position lasting many years.
The Lake Divider Curtain became the Red Line in the water for identifying serious nutrient overloads in freshwater lake systems. The location of the deployment was at Lake226 IISD-Experimental Lakes Area resulting in the banning of phosphorus in certain products globally.