[3] Located in southern Sonoma County, California, and a portion of northeastern Marin, the Petaluma River Watershed drains 146 square miles (380 km2).

The river is fully tidal 11 mi (18 km) from its mouth, indicating its slight gradient through the marshes below Petaluma.

The United States Army Corps of Engineers dredges this section to keep it navigable by gravel barges and pleasure craft.

mollis), Baker’s stickyseed (Blennosperma bakeri), Burke’s goldfields (Lasthenia burkei), showy Indian clover (Trifolium amoenum), and Sebastopol meadowfoam (Limnanthes vinculans).

[4] Steelhead (Oncorhyncus mykiss) that spawn and rear in the Petaluma River watershed are wild, not hatchery, stock.

The high school students constructed a salmonid hatchery in 1993[6] and in 2002 74 Chinook salmon returned to spawn in the Adobe Creek tributary.

The reported concerns involve the "loud noises it will create" that will scare away the birds and "throw off the entire ecosystem".

The oldest public bridge, built in 1925, is a 114 ft (35 m) concrete triple span carrying two lanes of Petaluma Boulevard North.

The new bridge is a 907 feet long, precast, post-tensioned spliced concrete girder design with three lanes of traffic in each direction and standard shoulders.