With 86,000 streams and 4,000 lakes within its boundaries, Pennsylvania appears to have no shortage of water.
However, concerns regarding the state's water supply have been raised with the emergence of the natural gas industry in the Marcellus Shale.
That is because an average of about 3 million gallons of water is needed to develop a single well in the shale play, and it is estimated thousands of wells will be drilled by the time the shale is fully developed over the coming decades.
Companies are withdrawing that water from streams, rivers, ponds, and public and private water systems with excess capacity.
Concerns have been raised that industry demands for water may adversely impact local water supplies and fish and aquatic life.
Those concerns were raised to an even higher level with the recent drought advisories issued by the state Department of Environmental Protection for the entire state.
The basin's water - as far as quantity is concerned - is safe, said Jim Richenderfer, deputy director for technical programs for the Susquehanna River Basin Commission, the agency that regulates water-quantity issues in the basin.
"There is no danger the gas industry will drain the basin of its water," Richenderfer said.
"SRBC is well aware that many citizens are particularly concerned about this summer's emerging drought conditions because of water usage by the natural gas industry for hydraulic fracturing in the Marcellus Shale region," said Paul Swartz, commission executive director. "The commission has existing, protective provisions in place ... for such times when stream flows are impacted."
According to Richenderfer, the gas industry is removing about 2 million gallons of water per day from the watershed, though it is permitted to remove 25 to 30 million gallons.
That is a drop in the bucket compared to the amount of water flowing out of the watershed at any given moment, he said.
"We have a decent idea that on average, there's about 18 million gallons per minute that flow from the Susquehanna to the Chesapeake Bay," Richenderfer said. "That equates to 26 billion gallons per day."
Richenderfer said the bay is the river's sole discharge point, though water also leaves the watershed through other means, such as evaporation and consumption.
Gas industry usage ranks fourth behind the water supply, power generation and recreation industries, according to the commission.
The water-supply sector - the largest water-consuming sector in the basin - is permitted to remove about 325 million gallons of water per day from the basin. The number-two and -three water-consuming sectors - power generation and recreation - are permitted to use 150 million and 50 million gallons per day, respectively.
Gas exploration companies seek withdrawal permits from multiple sources to ensure they have plenty to use in case one or more sources become unavailable, Richenderfer said.
They have a choice of where to truck or pipe water from, depending on the location of their well sites, he said.
"They want flexibility in their daily operation."
Although the agency requires a permit for the withdrawal of 100,000 gallons or more per day for consumptive use - defined as withdrawing water that will not be returned to its source - no such threshold exists for the gas industry here. A permit is required before a single drop of water may be withdrawn for shale development.
The gas industry already had set up shop in the basin by the time the commission realized how much water it needed to operate, Richenderfer said.
Once that became apparent, the commission acted quickly, ordering 23 companies that they needed permits to withdraw water for drilling operations.
"The industry didn't know we existed when they first came here," Richenderfer said. "I think some of the measures we took got their attention."
The commission also tweaked its regulations, requiring all water withdrawn for Marcellus Shale drilling to be permitted.
"We simply did not understand the industry when they came knocking, so to be conservative ... we set the threshold at one gallon," Richenderfer said.
The commission charges an applicant 28 cents per 1,000 gallons of permitted water.
"We get that with an obligation," he said. "The commission has to look for water to replace that water during drought conditions." Water replacement can be made through contracts the commission has with the Army Corps of Engineers to release water from dams into the watershed.
Safeguards are in place to protect streams and rivers during low-flow periods caused by extended periods of dry, hot weather, Richenderfer said.
The commission imposes "passby" limits that trigger when streams reach a specific low level.
Passby limits require a certain volume of water to be able to flow past and downstream of an intake. Once a passby threshold is breached, a company is no longer permitted to withdraw from that intake, Richenderfer said.
Passby levels are determined based on what is called "Q7-10."
Q7-10 is "the lowest seven consecutive day flow that occurs once every 10 years," Richenderfer said.
"It's a severe drought condition," he said.
If a company requests less than 10 percent of a specific body of water's Q7-10 level, no passby limit is set. If greater than 10 percent of Q7-10, a passby limit is set, he said.
The agency also sets "gallons per minute" withdrawal limits to prevent companies from withdrawing water too quickly and impacting a stream, he said.
SRBC officials said the dry summer proved the agency can successfully protect the basin's water resources from adverse impacts.
What happens to the water after the industry takes it to the well site?