The project is located on West Rosebud Creek, in Stillwater and Carbon counties, Montana.  The project occupies 673.54 acres and is located entirely within Custer National Forest owned by US Forest Service.

The Mystic Lake Project has two reservoirs: Mystic Lake, created by Mystic Lake dam, also the storage reservoir; and the West Rosebud Lake, impounded by Re-regulation dam, located downstream. West Rosebud Lake is used to moderate peaking flows from the powerhouse. Normal 0 false false false MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;}