Leave the mussels behind after boating on Lake Powell Utah Division of Wildlife Resources and last updated 2021-07-06 22:11:07-04 LAKE POWELL, Utah â Utah's Division of Wildlife Services (DWR) was busy over the Independence Day weekend helping to keep Utah free--free from invasive quagga mussels that cling to boats after leaving Lake Powell. What makes these mussels so bad? They can plug water supply systems, steal food from game fish, plug water lines, and damage boat engines. Statewide, the DWR together with Utah State Parks, Arizona Game and Fish Department, and the National Park Service inspected 19,025 boats and performed 381 decontaminations over the long weekend, slightly down from last year's totals.