Whatcom County's housing inventory was at its lowest level in nearly seven years last month, according to a new report.

The amount of available inventory of homes for sale in Whatcom County was at 5.8 months in October, the lowest level since February 2006, according to a study released by Coldwell Banker Bain. That inventory number means it would take that amount of time to deplete the supply of homes for sale if no more came on the market.

A rule of thumb is that if inventory supply falls below six months, it's indicative of a seller's market. If inventory is more than six months, then it leans toward a buyer's market. In early 2011, housing inventory was around 13 months.

Through October of this year, 1,829 homes were sold in Whatcom County, a 15.5 percent increase compared to the same period last year.

In a separate report, Whatcom County's mortgage delinquency rate posted a slight decline between August and September.

Whatcom's delinquency rate - the percentage of loans that are more than 90 days delinquent - was 4.26 percent in September, compared to 4.32 percent in August, according to CoreLogic, a national provider of financial and property information. The September rate is slightly higher than a year earlier, when it was at 4.20 percent.

Whatcom's delinquency rate remains well below the state and nation. The state's September rate was 6.57 percent; the U.S. rate was 7.69 percent.

The percentage of county mortgages in some stage of foreclosure continued to rise. It was 1.52 percent in September, up from 1.47 percent in August. In September 2011 the foreclosure rate was 1.17 percent.

The state foreclosure rate was 2.37 percent in September; the national rate was 3.25 percent.

Reach DAVE GALLAGHER at dave.gallagher@bellinghamherald.com or call 715-2269.