Hydrologists with the state Department of Water Resources estimate the Mokelumne, Stanislaus, Tuolumne and Merced watersheds, based on annual water year output, provide 6.76 percent of the state's water.

From the Mokelumne River watershed to below Lake McClure, people plan to pull trash out of four major waterways that flow through the Stanislaus National Forest this weekend.

There’s always trash in Mother Lode rivers, and multiple groups are seeking volunteers to take part in what’s organized as the 2017 Great Sierra River Cleanup.

In recent years, volunteers of all ages have combined to pull more than 800 tons of trash and recyclables from watersheds in the Sierra Nevada, according to the state nonprofit agency Sierra Nevada Conservancy.

From north to south in and near the 1,400-square-mile Stanislaus National Forest, here’s a breakdown of who’s doing what and where this Saturday:

• From 8:30 a.m. to noon, people with the Sierra Foothills River Cleanup will clean up the banks of the Mokelumne River and shoreline of Pardee and Camanche reservoirs. Volunteers should wear work clothes including long pants, sturdy boots or shoes, work gloves and bring a hat, sunscreen, insect repellent, and a canteen. Drinking water will be provided and Camanche Recreation Company will sponsor a free barbecue for volunteers at 12:30 p.m. at Camanche South Shore Recreation Area, north of Burson.

Volunteers younger than 18 are welcome with written permission from a parent or guardian. An adult must accompany those younger than 16. Flotation devices are recommended for children working close to the water. For more information email Ranger Lora Sparrowk at volunteer@ebmud.com or call her at (209) 772-8260.

• From 8:30 a.m. to noon, people with the Foothill Conservancy will clean up the Mokelumne River along Electra Road outside Jackson. Meetup is in the main beach parking lot. Volunteers should bring work gloves, filled water bottles, sunscreen and insect repellent. Sponsors will provide more drinking water and trash bags. No pets or alcoholic beverages are allowed. For more information, contact Carolyn Schooley at carolyn@foothillconservancy.org or (209) 223-3508.

• On Saturday, volunteer water quality monitors with the Alpine Watershed Group of Markleeville will gather trash at eight sites in the Carson River watershed in Alpine County. They also plan to pick up trash as part of a restoration project in Bear Valley on Sunday. For more information, contact Gavin Feiger, watershed coordinator, at awg.gavin@gmail.com or (530) 694-2327.

• From 9 a.m. to noon, people with the Bureau of Reclamation are seeking volunteers to help clean up multiple locations on New Melones. There will be trash and debris cleanup at sites around New Melones in the Stanislaus River watershed. Cleanup sites include the Tuttletown Recreation Areas, Mark Twain Day Use Area and Natural Bridges off Parrotts Ferry Road.

On-site registration begins at 8:30 a.m. at New Melones Visitor Center, 6850 Studhorse Flat Road. Volunteers will need to provide their own transportation. There also may be opportunities to do shoreline cleanup by boat. Register by calling (209) 536-9094, ext. 0. Volunteers should dress for the summer heat, wear a hat, sunscreen and sturdy shoes, bring snacks and water, and work gloves and trash grabbers if possible.

• From 9 a.m. to 1 p.m., people with the Tuolumne River Trust and Tuolumne County Resource Conservation District will clean up the Tuolumne River at Ward’s Ferry Road Bridge. Volunteers will float upstream on a barge and help to clean up the take-out area for whitewater rafters. Email volunteer@tuolumne.org to RSVP and secure space on the boat.

• From 9 a.m. to noon, people with the East Merced Resource Conservation District will clean up at locations downstream from McClure Reservoir including Schaffer Bridge at Oakdale Road, the Sante Fe Trestle and McConnell State Park outside Livingston, says Steve Starcher, a program coordinator. Volunteers on the water will work from kayaks and canoes to gather trash from Schaffer Bridge to Sante Fe Trestle, and from Sante Fe Trestle to McConnell State Park.

Organizers will provide canoes, kayaks, life jackets, paddles, trash bags and first aid kits. Volunteers need to bring leather gloves, closed toe shoes, water clothes, lunch, snacks and hand sanitizer. For more information, contact Starcher at admin@eastmercedrcd.org or (559) 289-8874.

This is the ninth annual Great Sierra River Cleanup. Organizers with the Sierra Nevada Conservancy say volunteers have pulled more than 815 tons of trash and recyclables from 2,600 river miles in Sierra Nevada watersheds.

Contact Guy McCarthy at gmccarthy@uniondemocrat.com or (209) 588-4585. Follow him on Twitter @GuyMcCarthy.