It's enough to put Yao Ming under water.
At 7 feet 5 inches tall, if Ming, the former NBA player from China, was to stand at the current water's edge of the Allegheny Reservoir, he would drown if the reservoir was at the usual summer level.
The reservoir is currently just under eight feet below maximum summer pool level 1,328 feet, or the benchmark level maintained in summer to allow room in the reservoir for flood mitigation.
Photo by Jacob Perryman
The deck of this platform near the Elijah Run Boat Launch on the Allegheny Reservoir usually sits near water level. The reservoir’s water level is currently eight feet lower than usually maintained in the summer.
At maximum summer pool levels, the reservoir generally reaches a maximum depth of just over 130 feet and an average depth around 48 feet. So, on average, there's still more than 40 feet of water under the surface.
During winter, the reservoir's maximum pool level is maintained 21 feet lower than in summer and the minimum pool level is set 67 feet lower still. At minimum pool levels, large sections of the reservoir bed would be exposed. The reservoir is still almost 13 and a half feet from winter levels, let alone overall minimums.
Over the reservoir's normal summer surface area of 12,080 acres, the current 7.6-foot difference in water level translates to approximately 333,670 cubic feet of water, or about 2.5 million gallons. That's assuming a uniform straight drop below water level and a level, even bed. The banks of the reservoir neither drop straight down nor is the bed of the reservoir a standard depth, so the actual volume is less than that. Still, it translates into a staggering amount of water.
It's being kept low on purpose.
According to the U.S. Army Corps of Engineers, which oversees reservoir level and outflow through Kinzua Dam, the reservoir's primary purpose is flood mitigation and regulation of water levels downstream of the dam. Low reservoir levels aren't a major concern.
Regulating water quality downstream from the dam was included as part of the initial dam/reservoir project when the dam was built. Regulating water quality through flow adjustments is actually a duty of the project mandated by law.
"A lot of our reservoirs have missions besides recreation," said Dan Jones, who handles public affairs out of the Corps of Engineers' Pittsburgh office. "Their main mission is low-flow augmentation and maintaining water levels for downstream transportation."
Low-flow augmentation means releasing enough water at the dam to keep downstream river depth and current speeds near normal.
With a dry early summer, much of western Pennsylvania is still under a drought watch designation with some areas still listed as holding emergency status concerning groundwater levels. The Allegheny River borders or flows through a majority of the counties effected, and the Ohio River, which the Allegheny empties into, runs through still more.
Kinzua Dam regulates water flow into the Allegheny River and therefore, more water flowing out of the dam means more water in those rivers. During periods of lower than average rainfall, more water flowing out of the dam also means lower than average reservoir levels.
"Low-flow augmentation helps reduce pollutants, which helps reduce (water) treatment costs and keeps consumer water prices down," according to Jones. "Maintaining flow for watercraft helps reduce energy costs for shipping."
According to Evan Skornick, northern area operations manager for the Corps' Pittsburgh District, actual impact on reservoir use from the lower water levels should be negligible.
"We keep an eye on recreational facilities," Skornick said. "We would see an impact at Elijah Run (boat launch) first."
According to Skornick, larger boats would begin to have difficulty using the ramp at Elijah Run if water levels were to drop an additional three feet. At approximately six feet below current levels, the ramp at the site could become unusable.
"We're not expecting to see impacts due to where the water levels are for at least three or four weeks," Skornick said, "well after Labor Day."
Skornick noted even those projections vary depending on rainfall.
So how much rain would it take to raise the water levels back to normal? According to Jones, it would have to be enough to break records.
"We've received some rain, but not enough," Jones said. "It would take a record rainfall in the month of August to bring levels to normal."