Eric Evenson-Marden's 15-year tenure as head of the Minnehaha Creek Watershed District has ended.

In a statement released Friday, district board President Sherry Davis White said Evenson-Marden had "left the organization." Evenson­-Marden said in an interview that his move wasn't voluntary.

"I knew there were a few issues with a few of the board members, but I did not fully anticipate this," said Evenson­-Marden. Board member Pam Blixt, an Evenson­-Marden supporter, said she was also caught by surprise.

In her statement, White said, "The challenges of protecting water quality in one of the largest urban watersheds in the state continue to grow, and we felt the district needed new leadership to guide the vision and work of the organization in future years."

The watershed district was named Watershed District of the Year in 2013 by the state Department of Natural Resources.

Prior to Thursday's board meeting, which included a performance review for Evenson-Marden, the district was named Watershed Hero by the Freshwater Foundation.

The district deals with water quality, shorelines, invasive species, flood control, stormwater, recreational and other issues from the western end of Lake Minnetonka, along the 22 miles of Minnehaha Creek to the Mississippi River, and around the Minneapolis Chain of Lakes.

It has a $13 million operating budget this year. It will collect $7.9 million this year from property owners in the 181-square-mile watershed, which includes all or parts of 27 cities and two townships in two counties.

Evenson-Marden will be replaced on an interim basis by David Mandt, the district's director of operations and programs who had been city administrator in Watertown until 2009.