Out of the 167,500 value notices mailed April 2 by the Williamson Central Appraisal District to residential property owners, more than half will show a decrease or remain close to the 2011 value.

According to a news release by the appraisal district, 51 percent of residential properties reflect a decrease in value, 36 percent show an increase and 13 percent remained within $1,000 of their 2011 valuation. This is the fourth consecutive year that the majority of values have decreased or remained the same.

Alvin Lankford, chief appraiser, said the valuations are determined by the home sales within a certain area.

"We are truly a mirror reflection of what's happening in the market itself, in the sales that are happening within those neighborhoods," he said.

Despite the dip in values, there were more than 2,900 new homes built in Williamson County in 2011, offsetting the decrease and causing the preliminary average home market value to rise less than 1 percent from $186,416 in 2011 to $187,451 for 2012.

The protest process has started in the county, so Lankford said the just over $1,000 increase in the average home market value may lessen somewhat by the time certification of the tax roll happens on July 25.

"By the end of the protest season, you may not see that full $1,000 increase, it may be something less," he said.

Lankford said residential growth is occurring in the larger school districts within the county, such as Round Rock ISD, Georgetown ISD and Leander ISD.

About 75,000 notices that the appraisal district sent out April 2 give the recipient the option to file a protest online. The district also recently launched a new website, www.wcad.org, that allows users to check home values in their area, watch informational videos and learn more about the appraisal process.