Here's a riddle: I run next to Ohio Stadium and along your favorite bike path in Clintonville. I'm a prime fishing spot and provide drinking water to Central Ohio. Once Downtown, I merge with another river and head south.

Here's a riddle: I run next to Ohio Stadium and along your favorite bike path in Clintonville. I'm a prime fishing spot and provide drinking water to Central Ohio. Once Downtown, I merge with another river and head south.

No clue?

That would be the Olentangy River, a waterway often confused with the Scioto River to the west or not considered at all. Its name shouldn't be a mystery, but few in Central Ohio have any contact with one of the state's most interesting natural resources.

For most people, it's noteworthy only when it floods or smells - the butt of a thousand uninformed jokes.

Starting on Earth Day, the Friends of the Lower Olentangy Watershed will renew their quest to change these attitudes.

"The Olentangy River is such a great resource in such a densely populated area," said Heather Dean, watershed coordinator for FLOW, an environmental group dedicated to maintaining the river and its tributaries. "It flows through Delaware County and Franklin County. So many people make use of it for so many different things."

On Saturday, April 18, FLOW is hosting numerous riverside cleanups, where volunteers can pick up trash, remove invasive species and plant native shrubs. Those interested can sign up to work with FLOW through Picture This 2009, a citywide Earth Day campaign headquartered at PictureThis09.org.

This spring, the nonprofit group also will help the green-minded remain involved after the holiday hoopla subsides. Its upcoming Watershed 101 course includes more than 40 hours of classes and hands-on field trips delving into topics like watershed history, geology, native plants and wildlife, wetlands and water treatment.

Classes will be held Saturdays starting April 25. They're free and open to the public, but registration is required.

"What we wanted with this course was something to meet the needs of someone who wants to get involved and learn more," Dean said. "The idea was to engage those who don't have a science background, but to be interesting for those who do. It gets back to valuing the resources where we live."

As Central Ohio continues to grow and spread, managing natural treasures like this storied river is becoming more important and more difficult. FLOW hopes to address both the river's rich legacy and how it's affected by development.

"We really have something for everyone," she added. "If you just want to come once a year and do a cleanup, we've got that. If you want to be on a committee and do more, we have those opportunities, too."

One goal of the series is to raise awareness of the Olentangy - to make it something the average person considers worth saving.

"People are consistently surprised by the Olentangy," Dean said. "A lot of time, people just don't realize what a resource the river is. Once you get to know it, you'll see how beautiful and diverse it is."

For more environmental news and outdoors adventures, click to The Riot Act blog at ColumbusAlive.com.