DES MOINES, I.A.(WNAX)- While we are at the end of the heating season, natural gas prices continue to rise.

Geoff Greenwood with Mid American Energy says while usage is going down, they are also ending a surcharge that people had been paying.

Natural gas is now over twelve dollars a therm, up four dollars from last year.

Greenwood says they expect more spikes before fall.

Greenwood says every energy source is impacted.

Mid American serves about ninety thousand customers mostly in southeast South Dakota.