The engineers had a mandate to keep the river at a certain height for navigation, and environmental concerns were not front of mind.

But about 20 years ago, the St. Louis corps began keeping the water a little lower when it could, maybe for around 30 days or so. Some of the taller, heartier river grasses began coming back.

“Now, we’re looking at if we can get it to 90 to 120 days,” said Dave Busse, the corps’ chief of engineering and construction. “Before we might have said, ‘OK, (the river grass is) five feet tall, let’s fill it back up.’”

Last year was the first time the corps really tried to keep the water levels low for an extended period, but unexpected heavy summer rain forced the corps to refill the pools to keep barges moving. This year, however, Busse said Mother Nature has cooperated exceptionally well, providing enough rain so the water levels are just right for the corps to manage the depths within the pools.

“I would put this as probably our best year ever,” Busse said.

While river grasses have been making a comeback for years, the extra time has just started to yield shorter, perennial river plants such as duck potatoes, Benjamin said. The hope is that healthier waterfowl and fish populations will follow.