The U.S. Environmental Protection Agency on Monday sent letters to governors and water regulators across the U.S. promising greater enforcement of rules to protect citizens from lead in drinking water in the wake of the crisis in Flint and urging every state to locate lead water lines as required.

As the Free Press reported Sunday, millions of lead service lines remain buried in cities across the nation, but in many cases water utilities are uncertain where those lines are, making it difficult if not impossible for them to be sure those utilities are testing for lead at sites considered the most likely to have contamination as required by the EPA.

The agency, which has been criticized by some for not moving more quickly in Flint after learning of high levels of lead in at least one home last February — and, two months later, that the water system was not practicing corrosion control as was required — also said it is is "increasing oversight of state programs to identify and address any deficiencies."

The EPA outlined its plans in two letters sent Monday: One, from agency Administrator Gina McCarthy to governors in 49 states; and a second, with more detail, from Deputy Assistant Administrator Joel Beauvais in the EPA Office of Water, to state regulators. The state of Wyoming did not get letters because it has not taken primary responsibility for drinking water, so it remains with EPA.