This is an excerpt of On Assignment, education writer Theresa Harrington's blog on Contra Costa County schools. Read more and post comments at IBABuzz.com/onassignment. Follow her at Twitter.com/tunedtotheresa or Facebook.com/TheresaHarringtonBANG.

May 9

The state released dropout and graduation rates for districts throughout California last month, showing that on average, 80 percent of students in the class of 2013 graduated in four years after starting as freshmen in 2009-10. This was up from just under 79 percent in 2012.

Meanwhile, the statewide average dropout rate fell from 13.1 percent in 2012 to 11.6 percent in 2013. In Contra Costa County, seven districts surpassed the state average graduation rate, while two fell below it. County dropout averages were not quite as stellar, with five districts posting lower dropout rates, three higher and one mirroring the state.

Here's a rundown of the countywide results, showing the change in graduation rates from 2012 to 2013 followed by the change in dropout rates from 201 to 2013, in percentages.

State: 78.9-80.2; 13.1-11.6

Contra Costa County: 83.9-85.8; 10.1-8.3

Acalanes: 97.7-97.8; 1.1-0.9

Antioch: 74.4-77.6; 16.8- 11.6

John Swett: 87.7-88.8; 8.5- 7.2

Liberty: 86.3-86.4; 3.5- 4.5

Martinez: 87.2-88.4; 6.7-9.7

Mt. Diablo: 81.2-82.6; 14.2-12.4

Pittsburg: 70.2-71.3; 21.6- 21.5

San Ramon Valley: 97.0-98.4; 1.6-0.4

West Contra Costa: 75.7-79.9; 18.2-13.2

The San Ramon Valley district had the highest graduation rate and lowest dropout rate in 2013, inching past Acalanes, which held that honor in 2012. More than 98 percent of San Ramon Valley seniors graduated on time last year, while less than 1 percent dropped out during their four years in high school.

San Ramon Valley spokesman Terry Koehne said his district's impressive numbers were the result of "a quality teaching staff that truly cares about kids and a very engaged parent community."

The tiny John Swett district also made gains, increasing its graduation rate by more than 1 percentage point to 88.8 percent, while reducing its dropout rate by about the same percentage to 7.2 percent. Superintendent Rob Stockberger credited the growth to teachers and administrators at John Swett High as well as alternatives for students who need more support.

"I think staff does a good job working with teens, but if the student becomes at risk, Willow Continuation High School becomes a really viable alternative," he said. "And in some extreme cases, we work with the county's Golden Gate Community School to come up with other viable options for students who are struggling in a larger environment."

The Liberty Union district saw slight improvement in its graduation rate, growing by one tenth of a percentage point to 86.4 percent. But, its dropout rate for students in the class of 2013 compared to the class of 2012 rose 1 percentage point to 4.5 percent.

Superintendent Eric Volta said these percentages don't tell the whole story because the class of 2013 was larger than the class of 2012. Even though more students dropped out, more students graduated. In the class of 2012, 1,487 students graduated after four years and 60 dropped out. In the class of 2013, 1,573 students graduated on time, while 82 dropped out.

"For whatever reasons, we lost more seniors last year," he said. "Had we kept the same number of seniors, our dropout rate would have gone down."

Most of the students who dropped out were enrolled in independent study or continuation high schools, he said.

Although the Antioch district's overall graduation rate fell below the state average, it showed significant improvement from 2012-2013, growing more than 3 percentage points. Its dropout rate plummeted more than 5 percentage points to 11.6 percent, equaling the state average.

"It's been a real concerted and focused effort," said Superintendent Donald Gill.

Staff writers Joyce Tsai and Paul Burgarino contributed to this report.