WATERTOWN A loud, motorized, whirring sound fills the nearly 90-year-old brick building off Marble Street as water flows unnoticed underneath until it pours out the other side of the historic landmark, much like an overflowing sink.
Thanks to three 20-ton turbines inside, the nearly 5,000-square-foot structure the Watertown Municipal Hydroelectric Plant powers all city-owned buildings and facilities. The plant generates about 9 percent of the citys annual revenues an average of nearly $3 million and is Watertowns fourth-largest revenue source, behind sales tax, property taxes and state aid, City Comptroller James E. Mills said.
Helped by a strong February, the city has earned $2.82 million from the facility through April of this budget year, which ends June 30. So far, May is doing extremely well, according to city Water Superintendent Michael J. Sligar, who oversees the hydro plant, built in 1927.
Its a gold mine, said Jeffrey C. Hammond, a civil engineer in the city engineers office.
The city owns, operates and maintains the plant the only municipal hydro facility along the 125-mile-long Black River, which begins just above Lyons Falls and empties into the eastern portion of Lake Ontario.
There are 16 other hydro plants in the Black River Basin, and all are privately owned. Four of the 17 are in the city of Watertown.
Watertowns city-run facility harnesses the rivers energy by using simple mechanics to convert that energy into electricity. Its based on a basic concept water flowing through the plants dam turns the turbines, which turns a generator.
Hydroelectricity is a natural for Watertown. As the Black River traverses the city from east to west, a 47-foot drop in elevation causes the water to speed up as it flows downhill, turning it into a powerful force, according to Mr. Sligar.
Producing a maximum of 125,000 kilowatt hours per day, Watertowns hydro plant supplies electricity to City Hall, the water and sewage plants, the Watertown Municipal Arena and other Parks and Recreation Department facilities.
The city sells any excess electricity to power giant National Grid. If the municipal plant produces more than 900,000 kilowatt hours in a month, the city sells the electricity to National Grid for 18.36 cents per kilowatt hour. This month, National Grids residential rate for electricity, not counting delivery costs, is 8.2 cents per kilowatt hour.
It makes economic sense for the city, Mr. Sligar said.
The citys lucrative 38-year agreement with National Grid expires in 2029. City officials said they hope to iron out a new agreement before then.
For the most part, the hydroelectric plant has been a big moneymaker since it was renovated during the early 1990s, Mr. Sligar said. During the past five budget years, the plant has generated an average of $2.87 million in annual revenues for the city, with a high of almost $3.1 million last year.
But Mr. Sligar said the revenues depend on how much water runs through the plants three turbines, which are nicknamed Faith, Hope and Charity. The amount of precipitation in the river basin has a direct correlation to how much electricity can be produced at the plant, Mr. Sligar said.
Initially, snow has little impact on how the computerized hydro plant runs, Mr. Sligar said. Thats because only water can flow through the turbines, which powers the system. Its only after snow melts and turns into water that the turbines convert it to electricity.
Mr. Sligar watches two large monitors that gauge water flow; he checks the algorithm of the flow before determining how many turbines should be running.
It totally depends on Mother Nature, and we cannot predict (that), Mr. Sligar said.
When theres enough water, all three turbines run at capacity. When the water flow isnt as high, either two, one or none operate, he said.
According to city records, the plant had its best February in at least seven years this past winter, generating nearly 29 percent more power than usual for the month when all three turbines were used. Mr. Sligar attributed the production strength to higher-than-average rainfall for February.
March, April and May usually are the strongest months for the hydro plant, Mr. Sligar said, citing the amount of snowmelt that occurs and the rainfall during the spring. He said July, August and September normally are the driest months, so power production is low, and January and February are down months until a thaw occurs.
This spring has been a roller-coaster season for generating power. First, March wasnt very productive because of a lack of river water due to a late thaw and ice that remained on the river. Only one turbine was used for the month, except in a four-hour period March 31, when two turbines ran, Mr. Sligar said.
In April, it was the opposite problem. Mr. Sligar blamed too much water caused by flood-stage levels in the river for not operating the three turbines at their full potential for much of the month.As a result, it was an average April, when 2.8 million kilowatt hours of power were produced and two turbines were used for a part of the month.
This month, the plant is generating 166 percent more power than usual for the month, Mr. Sligar said.