Rhode Island’s housing market deteriorated at the end of last year, as single-family sales slowed to a crawl, prices inched down and inventory rose, according to two separate reports.

The Rhode Island Association of Realtors reports today that fourth-quarter house sales plummeted more than 19 percent, while the median price during October, November and December fell nearly 6 percent, to $259,000.

For all of last year, the median price of single-family houses fell 2.6 percent, to $275,000, the lowest since 2004, according to the Realtors.

At the current pace of sales, it would take about 10 months to sell all the 6,100 single-family houses listed with real-estate agents at the end of last year, compared with 6 months at the end of 2005.

Thirty-two of Rhode Island’s 39 cities and towns reported median house-price declines last year, according to the Realtors. Six communities reported prices increases and one showed no change.

Boston-based research firm The Warren Group reported separately price and sales declines that were somewhat steeper than those in the Realtors report, with single-family house sales last year down 11.2 percent, ending the year with the lowest sales volume since the group began tracking the data in 2005.

The Warren Group reported that the median price for a single-family house in Rhode Island last year fell nearly 5 percent, to $254,000.

The Warren Group data includes properties sold by owners as well as real estate agents; the Realtors only report sales assisted by real estate agents.

In Massachusetts, single-family house sales last year declined 8.4 percent, and the median price dipped 4.6 percent, to $310,000, The Warren Group reported.

The Warren Group’s chief executive officer, Timothy Warren Jr., said in a statement that Rhode Island’s real-estate market deteriorated sharply at the end of last year — single-family sales in December plunged nearly 24 percent — so “we have to watch the market during the first quarter” because “there could be more bad news in the coming months.”

Rhode Island’s condominium market also slowed, the report said, with sales for last year down 6.8 percent and the median price down about 1 percent, or $2,000, to $225,000.

The Warren Group reported that house prices last year declined in all five Rhode Island counties. The most dramatic decline was in Providence County, where the median price of a single-family house last year fell 7.5 percent, to $231,300, compared with $250,000 in 2006. Providence County’s single-family house sales for the year fell more than 15 percent, according to The Warren Group.

The median price last year fell 4.3 percent in Washington County, 4.7 percent in Newport County and 3.5 percent in Kent County. The Warren Group reports that the median price in Bristol County last year fell 6.2 percent, but that number could be skewed because the data do not include Barrington.

The Barrington assessor’s office does not classify properties by type (condo, single-family, multifamily) nor does it differentiate between residential and commercial, so researchers have been unable to properly categorize sales, said The Warren Group’s data analyst, Alan Pasnik.

The Realtors reported that the median price of single-family houses sold in Barrington last year rose 3.6 percent, to $433,500. The Realtors also reported house-price increases last year in Westerly, Newport, Jamestown, North Smithfield and Hopkinton.

The median single-family house price in Providence (excluding the East Side) last year fell 7.3 percent, to $197,000. On the East Side, the median price fell 6.7 percent, to $468,075.

Prices of single-family houses last year also declined in other urban communities including Warwick, Cranston, Pawtucket, Johnston and Woonsocket, the Realtors reported.

Many of the suburban communities also recorded price declines, although most were not as pronounced. Some notable exceptions were Smithfield, where the median house price fell 14.6 percent, to $286,000, and West Greenwich, where the median price fell 11.5 percent, to $345,000.

“The correction that began in 2006 continued throughout 2007,” The Realtors president, Robert Scaralia, said in a statement. “The Federal Reserve’s recent rate drops should help balance the market further [and] more favorable interest rates will decrease housing inventory as homes placed on the market due to strained finances are refinanced.”

larditi@projo.com