How about a giant pool liner! :)
LOL
When I was younger, my brothers & I dammed a small cold water mountain creek next to our camping property (family privately owned). Used round boulders to build the base then placed black plastic liner on the upstream side. We left an "overtopping control" section in the center a few feet wide.
We quickly learned that we could not safely walk through this center section. That water was near ice cold & you didn't want an instant bath. So we learned to walk/wade around it in the center area.
The trout fishing was amazing. But the yellow jackets AND hornets were pesky. The river valley was named "Twisp", which is an indian translation for "you see 'um many bees" (I forgot the exact wording but it was a name associated with bees).
The bald faced hornets are "meat bee" machines. We once forgot & left a fresh trout on the picnic table. Came back in a few hours and only a perfectly picked clean skeleton remained. Sheesh.
Our entertainment was watching the bald faced hornets attack and eat the yellow jackets. It was interesting as the yellow jackets were more maneuverable, yet smaller, but they would gang up on the hornet if it attacked a fellow yellow jacket. The hornet would hover & wait for a yellow jacket to wander by & then it would attack. We built a homemade 5 gal bucket bee trap (oil layer on water fill with a hanging piece of ham slice). The yellow jackets would gorge until they fell into the oil surface. So many bees died that the layer was almost 3 inches thick (yes there were that many ground nests all around). Once the population of the yellow jackets were greatly reduced, the hornets had the upper hand. They would capture, sting, then take the yellow jacket to a pine tree, hook one of its legs on the pine needle junction, and hang upside down as it ate the bee. You would see the yellow jacket's wings flutter down as the bee was consumed. Then the hornet would go back down a inch or so off the ground to hover and wait for another victim. Bee wars.
btw - Safety tip: You had to search out the area for any underground nests if you had to make a momentary "pit stop".