Of the Bay states, only Maryland has a comprehensive water management policy that allows the regulation of consumptive water use.

The state requires a permit for all surface and groundwater withdrawals and, if necessary, the state can require that consumptive use of water be discontinued — or that provisions be made to replace the water — during times of short supply.

While it’s not a standard permit condition that someone must replace consumptive use water, state officials say they can revisit individual permits and adjust requirements if problems arise.

The state has a separate regulation for its portion of the Potomac River basin which requires anyone consumptively using 1 million gallons of water a day or more to either stop using water during times of low flow, or to furnish an alternative water supply to the river during those times The Potomac regulation was intended to support an agreement to maintain flows in the Washington area that dates to the early 1980s.

That agreement, worked out by the Interstate Commission on the Potomac River, allows water in upstream reservoirs to be released during times of extreme low flows to ensure there is enough water flowing by the Washington area to meet municipal water demand and maintain a 100-million-gallon-a-day flow in the river.

Maryland’s Potomac regulations were enacted out of concern that the growing demand for water would reduce the ability to maintain those flows as overall consumptive use of water increases.

In addition to the state regulations, the Susquehanna River Basin Commission has regulatory authority over consumptive use in the portion of Maryland that is in the Susquehanna watershed.

The state established separate regulations in the Potomac because — unlike the SRBC — the Potomac commission has no regulatory authority.

Neither Pennsylvania nor Virginia have statewide programs to address consumptive use, though the Susquehanna portion of Pennsylvania is regulated by the SRBC.