That wasn’t a Christmas card from Cascade Natural Gas in local mailboxes earlier this month. The local natural gas utility is notifying customers that residential rates are rising 18 percent, effective on the first of this month. Cascade filed for the rate increase in September, citing a rise in the cost of gas pipelines, reservation and storage costs. Cascade General Manager and Executive Vice President Scott Madison says that this is a “straight pass-through” of their increased costs. Commercial gas rates are also going up 20 percent. Cascade Natural Gas has 260,000 residential and commercial customers in Washington and Oregon.