Rusty Creek and the lakes are part of the Waterhen River drainage basin.

It features a solar-powered water system, composting toilets, food storage lockers, a six tent cluster site, culvert barbecues, and a picnic shelter.

[11] The lake's inflow from Third Mustus is at the northern shore and the outflow is at the eastern end.

Fourth Mustus Lake 54°27′52″N 108°51′23″W / 54.4645°N 108.85635°W / 54.4645; -108.85635[14] is the smallest at 62.6 ha (155 acres) in size and has an elevation of 512 m (1,680 ft) above sea level.

Fish species found in the lakes include northern pike, walleye, and yellow perch.