"Roughly a decade ago, when officials in Pennsylvania’s York County were struggling to put together Chesapeake Bay cleanup plans, they ran into a problem: No one believed their numbers.

The county’s plans were based on goals established by computer models from the state-federal Bay Program partnership. The strategy called for municipalities, agencies and farmers to sharply ramp up efforts to reduce nutrient pollution entering waterways from livestock manure and fertilizer.

But in meetings, local officials and farmers were skeptical about whether those figures reflected reality — or showed results of cleanup actions they had already taken.

'The model was not well believed. I’ll say that,' said John Seitz, a senior planner with the county planning commission. 'Everybody, but farmers especially, were saying "nobody wants cleaner water more than we do, but the model just doesn’t fit."'

It’s not unusual for state and local government officials to dispute computer model figures used to set nutrient reduction goals and assess progress.

But the York County Board of Supervisors did something others rarely do. They contracted with the U.S. Geological Survey to install state-of-the-art water quality monitoring devices on six streams in the county to see if model figures were, in fact, reflecting reality. . ."