They waited. And waited. And waited some more.

It was a good thing they had something to do. While waiting for the governor and a bevy of officials to arrive at the Arlington Echo Outdoor Education Center on Wednesday, a few dozen kids tooled around the Severn River in canoes, checked and rechecked the water quality and planted plugs of grasses along a beach. They practiced how they'd explain dissolved oxygen and pollution to the officials and the TV cameras.

Nearby, up on a hill, more than 100 teachers, parents and activists milled around, munching on snacks and talking about getting kids out in the great outdoors.

They...