A case of “human error” caused 2,500 gallons of diesel fuel to spill at a Massachusetts Water Resources Authority plant in Cambridge yesterday morning, with about 1,000 gallons of the fuel leaking into the Charles River.

According to Ria Convery, a spokeswoman for the MWRA, a crew discovered diesel spilling onto the plant’s parking lot around 12:15 a.m. yesterday. The site of the spill was an unmanned station on Memorial Drive near the Boston University bridge.

MWRA provides water and sewer services to the greater Boston area.

Frederick A. Laskey, MWRA executive director, said that “human error” in the configuration of the facility’s valves caused a tank to be overpressurized, resulting in fuel going through the vent of the facility. The fuel spilled first onto the roof, then onto the driveway, and eventually into the Charles.

“Our staff, immediately when they discovered it, stopped the overflow and then placed oil absorbent tubes to stop the flow,” Laskey said. “Unfortunately, some of it came down into the river.”

Clean Harbors, a hazardous waste disposal and response company, is currently cleaning the river. Laskey said he anticipates their work to take several days.

The Massachusetts Department of Environmental Protection is leading the government response to the spill, according to a press release from the Coast Guard.

Laskey said the DEP, the Environmental Protection Agency, the Coast Guard, Massachusetts State Police, and the Cambridge Police and Fire departments were all involved in the response, but the fire department’s Deputy Chief Gerard E. Mahoney criticized the MWRA for calling them almost three hours after the spill was discovered

“As I conveyed to the MWRA people there this morning, the delay in the notification of the fire department was unacceptable,” Mahoney said. “They assured me this morning that it wouldn’t happen again.”

Laskey said that he does not think crews at the facility initially thought to call the fire department—instead, they focused on containing the oil, he said—but Laskey acknowledged that the criticism was warranted.

“We should have called him immediately when oil was seen on the ground,” he said. “It’s a good suggestion and a lesson learned.”

Mahoney also criticized the MWRA for not having an “emergency action plan.”

“When I asked for it, they couldn’t find it,” he said.

Laskey maintains that the MWRA has strong standard operating procedures.

Contrary to forecasts of heavy snow, the weather aided in the initial response to the spill, Laskey said.

“If we had the heavy snow and high winds that we’ve predicted, it would have been really bad,” he added.

—Staff writer Naveen N. Srivatsa can be reached at srivatsa@fas.harvard.edu.