The graphs on the left show the rate of growth compared to the earliest year for which we have data -- in most cases 2003. The gray lines represent a theoretical constant annual rate of change. The bar charts on the right show the actual values for each year we have data.

Limitations

Each state tracks oversight of oil and gas wells differently. In some states, the numbers for enforcement staff represent staff members whose jobs revolve around enforcement, including field inspectors, supervisors and attorneys who handle enforcement cases. In other states, such as New York, enforcement staff is more broadly defined because all of the agency's employees are involved in enforcement to some degree. In some states, such as Nebraska, enforcement actions are not tracked consistently, so officials would not release data. The total well count provided by each state also varied. Some states provided producing oil and gas wells while others included injection, disposal and shut-in wells in their reported figures. Each state page lists how that state reports its data.