Big Rock Ranch

High HazardSatisfactory ConditionEmergency Action Plan: Yes

Location

CountyMarin
Nearest CityNicasio
River/StreamNicasio Creek Trib To Lagunitas Creek
Coordinates38.05060, -122.62770

Physical Characteristics

Dam TypeEarth
NID Height45 ft
Dam Height45 ft
Dam Length490 ft
Year Completed2002 (24 years old)

Storage & Hydraulics

NID Storage91 acre-ft
Max Storage91 acre-ft
Surface Area7 acres
Drainage Area0 sq mi

Ownership & Safety

PurposeWater Supply
OwnerLucasfilm, LTD
Owner TypePrivate
Hazard ClassificationHigh
Condition AssessmentSatisfactory
Last Inspection12/17/2025
Emergency Action PlanYes

Identifiers

NID IDCA01457
Federal IDCA01457
More InfoState Dam Safety Program

Nearby Dams

Novato Creek 4.7 mi High Peters 5.5 mi High Bon Tempe 6.5 mi High Seeger 7.2 mi High Phoenix Lake 7.2 mi High Lagunitas 7.3 mi Significant Hagmaier South 7.6 mi Significant Alpine 7.6 mi High Mill Pond 8.1 mi Significant Dolcini 8.5 mi Low