The results of making a pretty yard may get ugly for storm sewers and the North Platte River if you let the leaves and grass get in the gutters.

"Anything like grass clippings, leaves, dirt or any litter that's left in the gutter can get picked up by rain and moved into the storm drain," said Beth Andress who does public services education for the City of Casper.

"So when that stuff goes into the storm drain it clogs up the storm drain, which means we can have localized flooding," Andress said. "It also can be carried to the river because storm water is never treated. It drains directly into our creeks and then into the river."

Grass clippings aren't completely natural because they are cut, which would not happen normally, she said.

When grass breaks down, it creates nitrogen. That feeds algae, which can harm local aquatic life like fish and ducks, Andress said.

So to join Casper's informal "don't clutter the gutter" campaign, Andress urges people to mow so the clippings are blown onto their lawns. Clippings that land on the sidewalks and gutters should be returned to the lawns.

The same advice applies to dirt, gravel, oil and litter, she said.

If you spill oil, spread sand to absorb it, and put it in the trash, Andress said.

The city's Code Enforcement Division can cite residents for not complying with the ordinances about litter and waste disposal by throwing, leaving or dumping anything besides water into the gutter or storm drain system.