While the city ran on diesel, the lakes of Snettisham filled.
"The lakes are much higher than they were last year at this time," said Scott Willis, spokesman for Alaska Electric Light and Power Co., Juneau's electric utility. "The higher the lakes are, the more likely that we will fill the lakes by this fall and spill water."
Higher levels in Crater Lake and Long Lake, which power the Snettisham Hydroelectric Project, make electricity cheaper for AEL&P's regular customers because spillover translates into surplus energy.
Certain customers, deemed "interruptible," only get to plug into the grid when there's a surplus.
First-priority interruptible customers are those with dual fuel systems who have signed up as interruptible, about 100 homes and some government buildings, including the Federal Building. Next priority are the Hecla Mining Co.-owned Greens Creek Mine and Princess Cruise Lines ships.
Of the money paid by those customers, between 0.5 and 1.5 cents per kilowatt-hour goes toward the cost of the program. The rest subsidizes regular customers' rates.
But AEL&P has to make the call to sell surplus energy before any water spills. It's an educated guess.
Ordinarily, AEL&P headquarters gets automatic electronic measurements of the lake levels. That system went off-line along with the transmission lines, taken out April 16 by avalanches. The transmission lines are back up, but the automatic measurements are not; the utility measured lake levels manually June 1.
Willis said he'll decide around July 1 whether to turn on interruptible customers. At this point surplus seems likely, he said.
"Because I want to make sure that we reserve enough water for our firm customers, I'm going to be more conservative about turning them on," Willis said.
Last summer, AEL&P officials anticipated a surplus and sold electricity to interruptible customers.
They were wrong. The lakes didn't fill in the fall as much as the utility had expected.
As a result, AEL&P had to use some diesel during the winter, the cost of which was tacked onto the regular rate for firm customers. That cost of power adjustment of 3 cents was suspended in May while customers paid a 42-cent emergency rate adjustment for running the city on diesel, but the balance remains.
• Contact reporter Kate Golden at 523-2276 or e-mail firstname.lastname@example.org.