Duck run flooring?

[Duckchickenmamma]

I recently built a duck run that is attached to their coop. At first the floor of the run was just dirt. They made a muddy mess with their water. I put their waterer in a large feeder bowl. They were still making a mess. I put down small pebbles which looked really good the first few days. Now they are making a huge mess with their feed and water and the pebbles are impossible to keep clean. Does anyone have any suggestions for flooring in a duck run? I would like to keep the pebbles so suggestions for easy cleaning?

 

[Welshies]

Slope your run, put down a tarp that drains into a ditch or gutter (slope it), then put pebbles over top. Requires landscaping but you can just hose everything clean now.