Work begins this week on 30 miles of Sonoma County creeks and flood control channels, where crews will be thinning trees, removing sediment and planting trees, grasses and shrubs.

The annual summer work program by the Sonoma County Water Agency is expected to cost about $7 million.

?Without the work ... we would have the risk of flooding,? said Jon Niehaus, the Water Agency?s program coordinator.

In the past 12 years, however, the work has also been structured to accommodate fish habitat and nesting birds, said Keenan Foster, the Water Agency senior environmental specialist.

Workers will thin and remove arroyo willows, which are multi-trunked and catch debris and cause sedimentation. The trees will be replaced with single-trunk red willows and pacific willows, which will grow 45 feet high and create a 45-foot-wide canopy to shade the creeks, providing cooler water and better fish habitat.

Foster said 2,000 to 3,000 trees will be planted.

Crews will also remove 11,000 cubic feet of sediment from seven creeks, and use rock, erosion cloth, trees and shrubs to stabilize the banks on six creeks.

The work on three-dozen creeks from Windsor to Petaluma starts Thursday, after bird nesting season, and ends in mid October, before the fall migratory run of steelhead and salmon.

Crews will begin by removing vegetation at Roseland and Piner creeks. The largest project will be three miles of Santa Rosa Creek from Willowside Road to the Laguna de Santa Rosa.

?It is our biggest flood control channel, the backbone. We are working on two or three sections of Santa Rosa Creek every year,? Niehaus said.

That section of the creek is now choked with willows, which catch debris, cattails and sediment, Niehaus said.

The work is paid for with property taxes levied in flood control zones.

This year, there will be crews made up of 250 at-risk youths, ages 14 to 24, who will be paid as part of a $1.2 million program using federal stimulus funds. At the same time, the participants will be learning about stream ecology.