Flathead Electric Cooperative members will see bigger monthly bills starting May 1.

The cooperative’s board of trustees on Friday unanimously approved a rate increase that will bump the monthly basic service charge from $16 to $18.91 for residential single-phase service, which accounts for about 84 percent of all co-op services.

Flathead Electric’s new basic service charge is lower than some area electric cooperatives.

Neighboring Lincoln Electric Cooperative charges a $20 basic charge and 7 cents per kilowatt-hour. Missoula Electric charges a $24.87 basic rate, plus 6.3 cents per kwh. Marias River Electric is one of the lower-priced cooperatives at $12 for basic service plus 6.1 cents per kwh.

Flathead Electric’s residential basic service charge increase is offset by a new three-tier rate structure that encourages conservation by charging more for higher kwh usage.

Currently, single-phase residential members are charged 5.7 cents per kwh. Under the new structure, those same customers will pay 5 cents per kwh for the first 600 kwh; 6 cents for the second tier of usage, 601 to 3,500 kwh; and 8.7 cents for usage beyond 3,501 kwh monthly.

The proposed tiered rates limit the monthly increase to $3 or less for 79 percent of services, or 40,799 meters, according to Flathead Electric Director of Regulatory Affairs John Goroski.

For commercial users, basic service charges also will increase but the existing rate structure will be maintained. Declining block rates will be eliminated for larger users. Commercial users are grouped into small, medium, large and extra large users.

The overall 2.5 percent rate increase is based on the co-op’s cost of service analysis and is structured to absorb the effects of a nearly 7.5 percent rate increase in wholesale power rates from BPA that took effect last October.

The board opted to wait until spring to help its customers get through the winter heating season.