Housing prices in Westchester and Putnam counties continued to plunge in the first quarter, real estate agents reported.

The median sale price of a single-family house in Westchester slid to $505,500, 8.5 percent less than the year-ago quarter and the lowest level in a decade. In Putnam, the price decline was even steeper, falling 20.5 percent to $277,500.

The median price reflects the midpoint of all sales and is unaffected by properties priced at the extremely high or low ends.

Still, the average price of single-family homes followed a similar trend. In Westchester, the average price of a single-family house fell to $725,191 in the first quarter, a 4.7 percent decline from the 2011 period, while Putnam properties slid to $310,096, an 18.2 percent dip.

The report from the Hudson Gateway Association of Realtors found that the pace of sales closed in the quarter remained generally flat. While single-family house sales edged up 1.4 percent and condominium sales rose 5 percent in Westchester, cooperative unit sales skidded 3 percent and 2- 4-family house sales declined 8.8 percent.

In Putnam, which has a negligible market for condos and co-ops, the number of single family houses sold fell by 19.4 percent.

The pricing and sale data are considered lagging indicators, the report noted, given the time required to list, market and close on properties.

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Some factors that the report said could bode well for the market include: mortgage rates that remain below 5 percent; a strong stock market, and a "manageable" foreclosure market.

Nationwide, there has been mixed news in housing. The number of contracts signed to buy homes dipped in February, but economists polled by Reuters for the S&P/Case-Shiller 20-city home price index forecast that the decline in home prices should end this year and begin to rise in 2013.