FLOWERY BRANCH — Chattahoochee Riverkeeper has worked the past 1½ years on a “seamless transition” in top leadership, as one of Georgia’s most recognizable faces in environmental advocacy heads into retirement.

The big change took effect Monday as Sally Bethea, the environmental watchdog group’s founding riverkeeper and executive director, hands over reins to a couple of longtime, loyal employees.

Jason Ulseth, technical programs director, becomes riverkeeper, and Juliet Cohen, who had served as general counsel, will serve as executive director.

“Sally has put a lot of hard work into teaching us all the lessons she has learned over the past 20 years,” said Ulseth, who lives in Cumming.

Bethea’s environmental passions actually extend into the 1970s, when she got caught up in the decade’s big environmental push into more awareness and stricter federal laws.

As a member of the Sierra Club, she found she “got mad about things being proposed in this state.”

Bethea went on to earn her master’s degree at Georgia Tech and work for the U.S. Environmental Protection Agency.

She “was in the right place at right time” as Laura and Rutherford Seydel founded Chattahoochee Riverkeeper in 1994. She recalled wanting “to focus on a specific resource and the thought of being the protector of a river like this one was pretty exciting ... and daunting.”

In a small organization, she served as both riverkeeper, the person overseeing program development and the organization’s chief spokesman, and executive director, or chief manager and fundraiser.

Over the years, the group grew from its Atlanta main office to satellite offices in Gainesville and LaGrange. The staff also grew, as did the annual budget, rising to $1.5 million.

“We have worked to ensure clean water laws are enforced and, when necessary, go to court,” Bethea said during an interview last week

She and Ulseth met recently with The Times of Gainesville at Aqualand Marina in southern Hall County, where the group’s floating classroom, Chota Princess II, is anchored.

Ulseth joined the staff seven years ago, after a stint at the Georgia Soil and Water Conservation Commission.

The Gwinnett County native, who developed a love of water after growing up fishing and boating on the Chattahoochee and Lake Lanier, said he had crossed paths with Chattahoochee Riverkeeper during his state work and “had a very large respect for the organization.”

When his predecessor moved on to another job, he jumped at the opportunity to apply.

“He was the best, most qualified candidate by far,” Bethea said. “It turns out he can drive a boat, too, and that’s very helpful.”

In 2010, Ulseth developed a program of monitoring community streams, including ones in neighborhoods and parks.

“They rarely receive any monitoring or testing, so we don’t know if they’re posing public health threats,” he said. “The program allows us to get long-term quality data on each of these streams and has enabled us to go out and find numerous sewer spills.”

The program moved into Hall County in the past couple of years, where the group is checking 15 streams that flow into Lanier.

Ulseth’s work with the group has been eye-opening at times, he said.

“I’ve really learned a lot about what the true threats are to the river,” he said. “We’ve been able to develop and implement programs [that have] been effective in monitoring our community’s waterways and addressing industrial facilities that have been polluting for years without any consequence.”

Bethea, 63, said she came to realize that, after two decades, she had done “as much as I could.”

“It’s time for younger folks in charge who will bring new perspective and energy,” she said. “It just seems like the right timing.”

Bethea now will serve as a “very part-time” senior adviser to the group. She said she hopes to lend a hand in developing a floating classroom on West Point Lake near LaGrange.

“I think it’s critical to educate kids on a boat like this one,” she said.

Ulseth, 33, said Chattahoochee Riverkeeper, meanwhile, plans to embark on a three-year campaign to increase programs in the river’s headwaters and Middle Chattahoochee region.

Those plans include opening a storefront office on the Gainesville downtown square.

“We have these great programs in metro Atlanta and on much smaller scale in our satellite areas,” he said. “We know they’re successful and that we can make an impact. We just need more resources to make a bigger impact.”