The median price of an existing Orange County home slipped by nearly $3,500 in July from June, while sales declined almost 15% from a month earlier, the California Association of Realtors said Tuesday.

The median price for an existing stand-alone OC home sold in July was $514,180, a 0.7% decrease from a month ago and up 2.8% from a year earlier.

The area’s median sales price now is up 21.5% from the recent bottom of the market, seen in January 2009.

Prices here still are off more than 31% from the peak of the market, when the median sales price for an OC home topped $747,000 in April 2007.

The number of sales here fell by 14.5% from a month earlier, and were down 12.6% from a year ago, the association said.

The annual decline in sales was more pronounced in other parts of the state last month. California home sales fell 20.8% in July compared to a year ago, and were off 10.9% from June’s levels.

On a national basis, housing sales in July dropped to their lowest level in more than a decade, 25.5% below year-ago levels. Last month was the first month that buyers across the country could not qualify for a tax credit of up to $8,000.

The Realtor association excludes condominiums from its figures.

Including condos, the median price of an OC home sold in July was $450,000, a $5,000 increase from a month earlier and a 7.1% increase from year-ago levels, according to San Diego-based MDA DataQuick, a unit of Canada’s MacDonald, Dettwiler and Associates.

The median sales price of an existing home in California was $314,850 in July, about a 1% increase from June and a 10.4% increase from a year earlier, according to the Realtor association.

Statewide median prices are up about 28% from the bottom of the market, but still stand 47% below the peak mid-2007 median price of $594,530.