ALERT: Update on status of the nationwide data transmission error that prevents stream gauge data collected at affected locations from being displayed on the Advanced Hydrologic Prediction Services (AHPS) webpages. The USGS has restored the transmission from all of their gauges or has placed them in a seasonal outage (some Alaska gauges). There are a few USGS gauges that the NWS is not yet receiving the new transmissions and NWS is working to get that data by alternate means. A map of the status of USGS gauges is here. The status map of gauge outages from other agencies is here. The situation has greatly improved and will continue to improve but at a slower pace. The outage maps will now be updated once per week on Thursday. We apologize for the service interruption and hope to have the data restored as soon as possible.

Weather Forecast Office Philadelphia/Mount Holly, NJ

Middle Atlantic River Forecast Center

Hydrograph

River at a Glance

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Inundation Mapping

Probability Information Weekly Chance of Exceeding Levels Chance of Exceeding Levels During Entire Period Short-term Probabilistic Guidance (Experimental)

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Printable Image About this graph Tabular Data (UTC) Tabular Data (EST) Datum: NGVD29 Metadata

NOTE: Forecasts for the Millstone River at Blackwells Mills are issued routinely year-round.

Default Hydrograph Scale to Flood Categories   Return to Area Map

Upstream Gauge

Downstream Gauge

Flood Categories (in feet) Major Flood Stage: 15 Moderate Flood Stage: 10 Flood Stage: 9 Action Stage: 7 Low Stage (in feet): 0 Historic Crests (1) 21.24 ft on 08/28/2011 (2) 21.01 ft on 09/17/1999 (3) 19.24 ft on 04/16/2007 (4) 18.68 ft on 08/28/1971 (5) 16.84 ft on 07/15/1975 Show More Historic Crests (P): Preliminary values subject to further review. Recent Crests (1) 12.58 ft on 05/28/2018 (2) 9.68 ft on 01/19/2015 (3) 15.87 ft on 05/01/2014 (4) 9.94 ft on 03/31/2014 (5) 13.77 ft on 09/09/2011 Show More Recent Crests (P): Preliminary values subject to further review. Low Water Records (1) 1.15 ft on 09/16/1923 For more information on your flood risk go to www.floodsmart.gov. Show FEMA's National Flood Hazard Layers FEMA's National Flood Hazard Layers not showing? Why aren't the FEMA National Flood Hazard Layers showing on the ESRI Map? Possible reasons: There are no FEMA National Flood Hazard Layers for the location which you are viewing on ESRI Maps. The FEMA Web Mapping Service (WMS) is down. Note: Your zoom level may have changed. ESRI's zoom levels must be between 14 and 16 to show National Flood Hazard layers.

Zoom Level:16 Legend FEMA Layer Gauge Location 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

If you notice any errors in the below information, please contact our Webmaster
13	Washington Street and several businesses are flooded.
10	The D&R Canal is flooded by the Millstone River.
9	Flood stage reached with flooding now along River Road in Blackwells Mills and S. River Street in Millstone. Base of Route 533 bridge floods. River Road between Yorktown and Amsterdam is subject to closure. Canal Road near Suydam Road floods.
7	Several more causways are closed due to flooding.
6	The Griggstown Causway is closed due to flooding.

About This Location

Latitude: 40.475000° N, Longitude: 74.575833° W, Horizontal Datum: NAD83/WGS84 River Stage Reference Frame Gauge Height Flood Stage Uses NWS stage 0 ft 9 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 26.97 ft 35.97 ft Older USGS topographic maps, NGVD29 benchmarks MSL Not Available Not Available Older USGS topographic maps, MSL benchmarks Other Not Available Not Available   Current/Historical Observations: U.S. Geological Survey (USGS) Data and Site Info for Blackwells Mills

Additional Information

Potential River Levels Used to Estimate the Chance of Flooding and the Range of Possible River Levels 3 Day (SREF) 7 Day (NAEFS) 7 Day (GEFS)     Note: Use the official hydrograph at the top of this web page for river levels within the next 48 hours. See the Product Description Document link for more details on the interpretation of the 3,7 day graphics.  Click individual graphics to enlarge. During winter months, cold and ice may result in inaccurate real-time stream stage and streamflow data. Adjustments or deletions of this data can only be done after detailed analysis.

Resources

Hydrologic Resources Text Products Past Precipitation Forecast Precipitation River Forecast Centers River Stage Summary Automated Flood Warning Systems Inundation Mapping Locations

Additional Resources Area Hydrographs NWS Precipitation and River Forecasting AHPS Iframes for Developers Mobile iNWS for emergency management Flood Damage Costs/Fatalities in the US, 1903 - 2014 AHPS Web Brochure Snow Information Ensemble River Forecasts Hourly Precipitation

Collaborative Agencies 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. NWS Information National Weather Service Philadelphia/Mount Holly Weather Forecast Office 732 Woodlane Road Mount Holly, NJ 08060-9615 (609) 261-6600 Ask Questions/Webmaster Page last modified: 21-Dec-2016 5:21 PM Disclaimer Credits Glossary Privacy Policy About Us Career Opportunities