Lake O' the Cherokees Subwatershed Association About The Lake o the CherokeesSubwatershed association Our Mission The Lake O The Cherokees Subwatershed Association LOTCSWA is comprised of a group of citizens whose mission is to protect and improve water quality through collaborative adoption of best management practices that will promote the health safety and economic prosperity of the Lake O The Cherokees SubWatershed Basin region. How we accomplish Our Mission The first step is to provide a framework for collaborative efforts of stakeholders that with state agency and tribal input will develop a watershed plan that provides the impetus for broad adoption of best management practices within the watershed. When implemented these practices will address the impairments within the watershed including excess nutrients and sedimentation. About Grand Lake Grand Lake O the Cherokees more commonly known as Grand Lake is the northeastern most manmade lake in Oklahoma.