Inspector checking a boat for invasive aquatic species at Blue Mesa Reservoir, Colorado, USA. Boats entering and leaving the reservoir are inspected for invasive species. Colorado's mandatory inspection program aims to keep zebra mussels, quagga mussels, New Zealand mudsnails, Eurasian watermilfoil, Asian carp, and rusty crayfish out of the state's waters. Photographed at Curecanti National Recreation Area, Colorado, USA.