The Deerfield River Watershed’s Chapter of Trout Unlimited is holding its annual “Single-Fly” Fundraising Tournament the weekend of June 3 and 4.

Participants will test their fly-fishing skill by using a single-fly pattern (three duplicate copies are allowed ) of their choice, for the entire weekend. Open to all ages and skill levels, participants can fish along any section of the Deerfield River.

The entry fee is $35 and all proceeds will help fund Trout Unlimited’s local land and cold-water fisheries conservation efforts.

Advanced registration is available at event sponsors: Deerfield Fly Shop, 8 Elm St., South Deerfield, and Overwatch Outpost, 97 Main St., (Route 2) Charlemont. Participants 15 years old and younger are free.

Anglers can also register on the day of the event (Saturday, June 3) at the Zoar picnic grounds on Zoar Road in Charlemont from 6:30 a.m. until noon. Further details can be found at: www.deerfieldrivertroutunlimited.com.

The tournament will end with a picnic at the Zoar picnic grounds on Sunday, June 4, at 6 p.m., and a subsequent drawing for prizes donated by all event sponsors that also include Cabellas gear and local fishing guide services, according to organizers.

The “Single-Fly” coincides with the state’s “Free Fishing Weekend,” meaning that fishing licenses are not required, but that all other rules and regulations set by the Massachusetts Division of Fisheries and Wildlife must be strictly observed. The “Single-Fly” is also a “catch and release” event, adhering to Trout Unlimited’s conservation philosophy of releasing fish to allow other anglers the enjoyment of catching them.

Also on June 3 at the Zoar picnic grounds, a companion event, Spey Day, will offer anglers the opportunity to explore and learn about the spey casting form of fly fishing from 9 a.m. to 3:30 p.m. Master spey caster and instructor Walt Geryk will be on hand to teach the basics of spey casting, which is growing in popularity among many fly anglers.

Proceeds from Spey Day will benefit Reel Recovery, a nonprofit organization that conducts free fly-fishing retreats for anglers recovering from all forms of cancer.