Americano Creek springs from low-lying coastal hills 4 mi (6 km) west of Cotati and runs westward, paralleling Roblar Road.

The lower reach of the creek flows westward past the small community of Bloomfield, paralleling Valley Ford Road, and passes under State Route 1, known locally as "Highway 1" or "the Shoreline Highway", at which point it begins to define the Sonoma-Marin county line.

Pollutants found at hazardous level in the creek have included fecal bacteria, copper, ammonia, and zinc.

[6] The creek's headwaters area is a historic habitat for a number of rare and endangered species including Sebastopol meadowfoam, Limnanthes vinculans; showy Indian clover, Trifolium amoenum; and Pitkin Marsh lily, Lilium pardolinum ssp pitkinese.

[4] For its first 8 mi (13 km), the stream meanders through a broad valley dominated by agricultural uses, principally cattle grazing.

Grazing is so intense that cattle are seen wading in a broad marshy streambed over 16 in (40 cm) deep and over 300 ft (100 m) wide.

Water testing of Americano Creek and Estero has generally found pH (acidity) levels in the range of 7.5 to 8.0, which satisfies the guidelines in the State of California Basin Plan.

[citation needed] In some years, a sand bar forms at the mouth of the estero, restricting tidal exchange.

Rancho Cañada de Pogolimi was a Mexican land grant given in 1844 by Governor Manuel Micheltorena to María Antonia Cazares, widow of James Dawson.

[10] The Ebabias Creek[11] tributary is shown on a diseño of the Rancho Cañada de Pogolimi grant in 1844 but the possible Indian origin has not been determined.

The newest of these, built in 1985, is the 73 ft (22.3 m) long concrete slab structure at Valley Ford Road, 3.6 mi (5.8 km) east of the junction with State Route 1.