Most state agencies don't want the triploids to get out into the public waterways which is why they want to see evidence that your spillways are caged.

Barricading the spillway is a double edged sword due to the potential for blockage that holds water and pushes the dam to it's limits.

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."