BETHEL — Preparations are under way for the Androscoggin River Watershed Council’s Source to the Sea Trek, which this month is celebrating its 15th anniversary.

 It will begin Friday, July 9, with a sunset paddle around Lake Umbagog, which straddles the Maine-New Hampshire border.

 It will then continue in a series of 19 day-trips as paddlers meander through northern New Hampshire and Western Maine until they reach Merrymeeting Bay in Bath.

 “The board decided for the 15th anniversary, we should do the whole thing,” trek organizer Jessie Seymour said late Monday afternoon in an e-mail.

She said she believes hundreds of people will participate in the journey.

Participation is free for source-to-sea “trekkers,” who need to bring their own paddle-powered boats, appropriate gear, and lunch.

Seymour said a voluntary, tax-deductible donation of $10 is requested to support the nonprofit Watershed Council, which supports costs of organizing the Trek.

 Many days include an educational component, with speakers on topics including history, ecology, conservation, and economic development in the area. Dates in the Bethel area include meeting at 9 a.m. on:

— July 16 – At the Shelburne Bridge in Shelburne, N. H., to paddle to Gilead. Fly fishing expert Bob Milne will discuss the revitalization of fishing in the northern Androscoggin.

— July 17 – At the Gilead Bridge to paddle to Bethel Outdoor Adventure Center. Jim Mitchell, executive director of the Mahoosuc Land Trust, will educate trekkers on the Mahoosuc Initiative, a regional conservation effort.

 —July 18 – At Bethel Outdoor Adventure Center to paddle to Hanover. The trek will be joined by a contingent from Maine Handicapped Skiing and Michele Windsor of the Oxford County Soil and Water Conservation District. Windsor will discuss aquatic insects.

More information on logistics, special events, and registration is available at the council website at www.androscogginwatershed.org. Paddlers may register by filling out a simple online form on the website, or by calling (207) 754-8158.

The nonprofit Androscoggin River Watershed Council was founded in 1999 with a mission to continuously improve environmental quality and promote healthy and prosperous communities in the Androscoggin River Watershed.

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