Shag Lake, located in Marquette County, Michigan, consists of two connected bodies of water - Big Shag Lake (194 acres) and Little Shag Lake (103 acres). The lake features a public boat launch on Big Shag Lake, which was renovated in 2015 with a new concrete ramp. Access is via Knudsen Road off Marquette County Road 557.

Watercraft regulations are specifically defined for both sections of the lake. On Big Shag Lake, high-speed boating and water skiing are prohibited between 6:30 PM and 10:00 AM. Additionally, a designated portion of Big Shag Lake requires slow-no wake speed at all times - this area lies between the northwest corner of government lot 4 and a line 500 feet south, running from the eastern to western shore. Similar speed and skiing restrictions apply to Little Shag Lake during evening and early morning hours.

The lake supports a diverse fish population including walleye, bluegill, bass, and northern pike, indicating a healthy aquatic ecosystem. The surrounding area is accessible year-round, though ice conditions affect winter access. The lake is situated in a rural setting near the communities of Gwinn and K.I. Sawyer.

A Recreation Passport is required for vehicle access to the boat launch. Paddlers should be aware of motorized boat traffic during permitted high-speed hours (10:00 AM to 6:30 PM) and plan accordingly. The designated slow-no wake zone provides a more protected area for paddling when motorized traffic is present. The lake's moderate size makes it suitable for day trips, with opportunities to explore both Big and Little Shag Lakes in a single outing.