Bids are due March 26 for Chelan County PUD’s latest auction of up to 5 percent of the output from its Rocky Reach and Rock Island hydroelectric projects, for either a 2.5-percent slice or for the entire 5-percent slice.

Bidders will be notified of the outcome within 90 minutes. The necessary contracts will be ­formalized by March 28, according to the timeline on Chelan PUD’s website.

The output includes energy, capacity and storage from the dams. For a 2.5-percent slice of an average water year, that would be 26 aMW of energy, 46 MW of capacity and 98 MWh of pond storage. A 5-percent slice would be 52 aMW of energy, 92 MW of capacity and 195 MWh of pond storage.

The contract duration on offer is from January 2020 through December 2024, and the delivery point would be from the Mid-Columbia.

Chelan PUD is also offering the slice product with environmental attributes, on a negotiated basis. ­However, the utility notes in its material on the auction that it ­cannot guarantee the product will comply with ­compulsory or voluntary renewable portfolio programs.

The utility began auctioning slices in 2010. It did not hold an auction in 2018, opting instead to ­negotiate two competitive contracts—a five-year deal with ­Avangrid Renewables and a 10-year deal with Avista.

Typically, Chelan PUD sells about 25 percent of output from Rocky Reach and Rock Island dams through slice contracts. If the upcoming bid is successful, the PUD will have 25 percent under slice contract through 2020.