Coeur d'Alene's Wastewater Utility Department is celebrating its 75th anniversary Friday with a free hot dog and hamburger lunch.

Wastewater Superintendent Sid Fredrickson said attendees can decide themselves whether to tour the Wastewater Treatment Plant before or after they eat.

An open house is set for 9 a.m. to 3:30 p.m. Friday, with hourly tours for ages 10 and older and a presentation on "What Happens After the Flush."

Fun, games and crafts for kids are also planned.

"I promise we won't have bobbing for Baby Ruth candy bars," Fredrickson said.

Lunch will be served from 11 a.m. to 2 p.m.

When the city's Wastewater Treatment Plant was built in 1939, Coeur d'Alene had a population of 10,000. Many homes were still on septic then, Fredrickson said.

Before that - dating to 1907 when the first sewer lines went in - what happened "after the flush" was it all went right into the Spokane River.

Coeur d'Alene's plant was one of the first in the Northwest, Fredrickson said.

"As a matter of fact, it went online 20 years before the city of Spokane's," he said. "We were ahead of the game."

In the 28 years he has been with the city, Fredrickson has seen firsthand Coeur d'Alene's tremendous population spurts and increasingly rigorous regulations aimed at protecting the environment.

When he first started, the city was still using much of the original 1939 treatment process. Since 1982, the plant has undergone 11 major upgrades.

People touring the facility are often surprised about the "absolute complexity of the facility," Fredrickson said.

Visitors to Friday's open house will be able to visit the plant's laboratory and watch videos of microorganisms feeding on sewage.

The open house is also an opportunity to admire recent additions of public art at the plant.

"One of the things we're also very proud of is the architectural features we've adopted," Fredrickson said. "Aesthetically, we look like a good neighbor rather than an old gray tank farm."

If you go ...

• Coeur d'Alene Wastewater Utility Department 75th Anniversary celebration:

Where: 765 W. Hubbard Ave., Coeur d'Alene

When: 9 a.m. to 3:30 p.m. Friday

Lunch served: 11 a.m. to 2 p.m.

Information: 769-2281