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Web Portal Changes: In Spring 2024, the Advanced Hydrologic Prediction Service (AHPS) hosted at https://water.weather.gov will be replaced by the National Water Prediction Service (NWPS) at a repurposed https://water.noaa.gov. A preview of NWPS is available here, where you can see your station hydrograph by replacing SSSSS with the station 5-character id: https://preview.water.noaa.gov/gauges/SSSSS.

Flood Inundation Mapping: Experimental real-time flood Inundation mapping services for 10% of the United States are now available via the NWS Map Viewer. Additional products and geospatial services depicting River Forecast Center and National Water Model forecasts continue to be accessible as described in the StoryMap here.

Please visit https://www.weather.gov/owp/operations for more information.



Hydrograph River at a Glance Download
Willow Brook at Old Redwood Highway Bridge Stage (ft)Highest Observation: 32.59 ft at 8:36PM Mar 13, 2024Highest Observation: 32.59 ft at 9:35PM Mar 13, 2024Observed: 32.57 ft at 10:33PM Mar 13, 2024Observed: 32.57 ft at 11:31PM Mar 13, 2024Observed: 32.57 ft at 12:30AM Mar 14, 2024Observed: 32.57 ft at 1:28AM Mar 14, 2024Observed: 32.57 ft at 2:26AM Mar 14, 2024Observed: 32.54 ft at 3:25AM Mar 14, 2024Observed: 32.54 ft at 4:23AM Mar 14, 2024Observed: 32.54 ft at 5:21AM Mar 14, 2024Observed: 32.54 ft at 7:18AM Mar 14, 2024Observed: 32.54 ft at 8:16AM Mar 14, 2024Observed: 32.54 ft at 10:13AM Mar 14, 2024Observed: 32.49 ft at 11:11AM Mar 14, 2024Observed: 32.54 ft at 12:10PM Mar 14, 2024Observed: 32.52 ft at 1:08PM Mar 14, 2024Observed: 32.49 ft at 5:01PM Mar 14, 2024Observed: 32.47 ft at 7:56PM Mar 14, 2024Observed: 32.49 ft at 8:55PM Mar 14, 2024Observed: 32.47 ft at 9:53PM Mar 14, 2024Observed: 32.47 ft at 10:51PM Mar 14, 2024Observed: 32.47 ft at 11:50PM Mar 14, 2024Observed: 32.44 ft at 12:48AM Mar 15, 2024Observed: 32.44 ft at 1:46AM Mar 15, 2024Observed: 32.47 ft at 2:45AM Mar 15, 2024Observed: 32.44 ft at 3:43AM Mar 15, 2024Observed: 32.44 ft at 4:41AM Mar 15, 2024Observed: 32.44 ft at 5:40AM Mar 15, 2024Observed: 32.44 ft at 7:36AM Mar 15, 2024Observed: 32.44 ft at 9:33AM Mar 15, 2024Observed: 32.47 ft at 10:31AM Mar 15, 2024Observed: 32.44 ft at 11:30AM Mar 15, 2024Observed: 32.44 ft at 12:28PM Mar 15, 2024Observed: 32.44 ft at 1:26PM Mar 15, 2024Observed: 32.47 ft at 2:25PM Mar 15, 2024Observed: 32.44 ft at 3:23PM Mar 15, 2024Observed: 32.44 ft at 4:21PM Mar 15, 2024Observed: 32.42 ft at 5:20PM Mar 15, 2024Observed: 32.42 ft at 6:18PM Mar 15, 2024Observed: 32.42 ft at 7:16PM Mar 15, 2024Observed: 32.39 ft at 8:15PM Mar 15, 2024Observed: 32.39 ft at 9:13PM Mar 15, 2024Observed: 32.39 ft at 10:11PM Mar 15, 2024Observed: 32.39 ft at 11:10PM Mar 15, 2024Observed: 32.39 ft at 12:08AM Mar 16, 2024Observed: 32.39 ft at 1:06AM Mar 16, 2024Observed: 32.39 ft at 2:05AM Mar 16, 2024Observed: 32.37 ft at 3:03AM Mar 16, 2024Observed: 32.37 ft at 4:01AM Mar 16, 2024Observed: 32.37 ft at 5:00AM Mar 16, 2024Observed: 32.37 ft at 6:56AM Mar 16, 2024Observed: 32.37 ft at 7:55AM Mar 16, 2024Observed: 32.37 ft at 9:51AM Mar 16, 2024Observed: 32.39 ft at 11:48AM Mar 16, 2024Observed: 32.39 ft at 12:46PM Mar 16, 2024Observed: 32.39 ft at 1:45PM Mar 16, 2024Observed: 32.39 ft at 2:43PM Mar 16, 2024Observed: 32.39 ft at 3:41PM Mar 16, 2024Observed: 32.37 ft at 4:40PM Mar 16, 2024Observed: 32.39 ft at 5:38PM Mar 16, 2024Observed: 32.39 ft at 6:36PM Mar 16, 2024Observed: 32.37 ft at 8:33PM Mar 16, 2024Observed: 32.37 ft at 9:31PM Mar 16, 2024Observed: 32.37 ft at 10:30PM Mar 16, 2024Observed: 32.39 ft at 12:26AM Mar 17, 2024Observed: 32.34 ft at 1:25AM Mar 17, 2024Observed: 32.34 ft at 2:23AM Mar 17, 2024Observed: 32.37 ft at 3:21AM Mar 17, 2024Observed: 32.34 ft at 4:20AM Mar 17, 2024Observed: 32.34 ft at 5:18AM Mar 17, 2024Observed: 32.37 ft at 6:16AM Mar 17, 2024Observed: 32.34 ft at 7:15AM Mar 17, 2024Observed: 32.37 ft at 8:13AM Mar 17, 2024Observed: 32.34 ft at 10:10AM Mar 17, 2024Observed: 32.34 ft at 11:08AM Mar 17, 2024Observed: 32.37 ft at 12:06PM Mar 17, 2024Observed: 32.37 ft at 1:05PM Mar 17, 2024Observed: 32.37 ft at 2:03PM Mar 17, 2024Observed: 32.37 ft at 3:01PM Mar 17, 2024Observed: 32.37 ft at 4:00PM Mar 17, 2024Observed: 32.34 ft at 4:58PM Mar 17, 2024Observed: 32.34 ft at 5:56PM Mar 17, 2024Observed: 32.39 ft at 6:55PM Mar 17, 2024Observed: 32.37 ft at 7:53PM Mar 17, 2024Observed: 32.34 ft at 8:51PM Mar 17, 2024Observed: 32.34 ft at 9:50PM Mar 17, 2024Observed: 32.34 ft at 10:48PM Mar 17, 2024Observed: 32.34 ft at 11:46PM Mar 17, 2024Observed: 32.34 ft at 12:45AM Mar 18, 2024Observed: 32.34 ft at 1:43AM Mar 18, 2024Observed: 32.34 ft at 2:41AM Mar 18, 2024Observed: 32.34 ft at 3:40AM Mar 18, 2024Observed: 32.34 ft at 5:36AM Mar 18, 2024Observed: 32.34 ft at 6:35AM Mar 18, 2024Observed: 32.34 ft at 7:33AM Mar 18, 2024Observed: 32.34 ft at 8:31AM Mar 18, 2024Observed: 32.34 ft at 9:30AM Mar 18, 2024Observed: 32.34 ft at 10:28AM Mar 18, 2024Observed: 32.34 ft at 11:26AM Mar 18, 2024Observed: 32.34 ft at 12:25PM Mar 18, 2024Observed: 32.34 ft at 1:23PM Mar 18, 2024Observed: 32.34 ft at 2:21PM Mar 18, 2024Observed: 32.34 ft at 4:18PM Mar 18, 2024PTMC1(plotting HGIRR) Graph Created (8:30PM Mar 18, 2024)ObservedLatest observed value: 32.34 ft at 4:18 PM PDT 18-Mar-2024. Flood Stage is 40.7 ft
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About this graph
Tabular Data (UTC)
Tabular Data (PDT)
XML Data
RSS Files
Datum: Not Available
Metadata
NOTE: Graphical forecasts are not available for the Willow Brook at Old Redwood Highway Bridge. During times of high water, forecast crest information can be found in the text products.
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Flood Categories (in feet)
Major Flood Stage: 44.3
Moderate Flood Stage: 43
Flood Stage: 40.7
Action Stage: 40.7
Low Stage (in feet): -9999

Historic Crests
Currently none available.

Recent Crests
Currently none available.

Low Water Records
Currently none available.
Zoom Level:14
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Gauge LocationGauge Map Marker
Disclaimer
Latitude/Longitude Disclaimer: The gauge location shown in the above map is the approximate location based on the latitude/longitude coordinates provided to the NWS by the gauge owner.
Flood Impacts & Photos Collapse
If you notice any errors in the below information, please contact our Webmaster
44.3 Major Flood Stage. Water level has reached by bottom of the bridge soffit.
43.9 Flood waters flowing down Redwood Way at Old Redwood Highway.
43.2 Water levels are above bankfull and begin flowing through upstream businesses, including passing through the old lumber company's parking lot.
43 Moderate Flood Stage. A local detention basin may begin to release water onto North McDowell Blvd. Ext.
42.3 Water begins to flow across Ely Road at the railroad track near Old Redwood Highway. Holm Road begins to flood and water ponds on North McDowell at the Post Office.
41.7 City of Petaluma will notify the City Manager and evaluate the need to activate the Emergency Operations Center.
40.7 Action Stage. NWS and City of Petaluma will be closely monitoring the situation. NWS will issue an urban/small stream advisory if not already issued.
About This Location Collapse

Latitude: 38.279722° N, Longitude: 122.669444° W, Horizontal Datum: NAD83/WGS84

River Stage
Reference Frame
Gauge Height Flood Stage Uses
NWS stage 0 ft 40.7 ft Interpreting hydrographs and NWS watch, warnings, and forecasts, and inundation maps
Vertical Datum Elevation
(gauge height = 0)
Elevation
(gauge height = flood stage)
Elevation information source
NAVD88 Not Available Not Available Survey grade GPS equipment, FEMA flood plain maps, newer USGS topographic maps
NGVD 29 Not Available Not Available Older USGS topographic maps, NGVD29 benchmarks
MSL Not Available Not Available Older USGS topographic maps, MSL benchmarks
Other Not Available Not Available  
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The National Weather Service prepares its forecasts and other services in collaboration with agencies like the US Geological Survey, US Bureau of Reclamation, US Army Corps of Engineers, Natural Resource Conservation Service, National Park Service, ALERT Users Group, Bureau of Indian Affairs, and many state and local emergency managers across the country. For details, please click here.
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Page last modified: 2-Nov-2020 7:27 PM
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