Serious and violent crimes in the Santa Clarita Valley dropped 17 percent over the past year and nearly 34 percent in the last five years, according to preliminary data released Wednesday by the Los Angeles County Sheriff’s Department.

The new figures show both the raw number of Part 1 crimes and the crime rate expressed in crimes per 10,000 population, for the first seven months of 2011.

Part 1 crimes include violent offenses – murder, rape, robbery and aggravated assault – and serious property crimes – burglary, theft, grand theft auto and arson.

Year to date through July 31, a total of 2,224 Part 1 crimes were reported in the SCV, an average of 10.4 per day. That’s down from 2,680 for the same period in 2010 and 3,033 for the first seven months of 2006.

Crimes per 10,000 population numbered 82.77, down 17 percent from 2010’s 99.74, and 33.9 percent lower than the 125.28 per 10,000 reported from January through July 2006.

Crimes dropped more sharply in unincorporated areas of the Santa Clarita Valley than in the city of Santa Clarita. Unincorporated SCV showed a 23.8 percent decline on the year (43 percent since 2006), while the city’s rate was only 14.1 percent lower (29.3 percent since 2006).

The unincorporated area also showed fewer crimes per 10,000 population (66.03) than the city (91.54).

Valley-wide, the homicide rate dropped by half – by virtue of the fact that one person was murdered during the 2011 reporting period (in unincorporated SCV) compared to two people in 2010 (one each in the city and the unincorporated area).

Next month’s figures are expected to show a reversal, following the Aug. 5 double murder-suicide in the Valencia Bridgeport area of the city.

The first seven months of 2011 showed a steep year-over-year decline in aggravated assault, grand theft auto and robbery throughout the SCV – down 43 percent, 33.1 percent and 31.6 percent respectively.

Of the Part 1 categories, only arson has showed an increase. A total of 22 incidents were reported locally this year versus 17 a year ago, equating to a 30.2 percent increase, adjusted for population.

Countywide for all Sheriff reporting areas, violent crime declined 11.74 percent for the period and serious crimes declined 4.45 percent. Together, all Part 1 crimes were down by 5.93 percent.

Every Sheriff station reported lower rates except East Los Angeles (up 6 percent), Century (9.51 percent) and Lomita (16.94 percent).