Millstone River at Blackwells Mills, Somerset County NJ (BKWN4)
Gage Location: Somerset County, New Jersey	Site Location: Somerset County, New Jersey
Latitude: 40.475	Longitude: -74.576	Elevation: 26.97 ft. MSL	Drainage Area: 258 Sq. Mi.
Minor Stage: 9 ft.	Moderate Stage: 10 ft.	Major Stage: 15 ft.
First Flood: 1924-04-07	Last Flood: 2011-12-08 Crest: 10.79 ft.	Datum change: 1928-08-17	Number of Floods: 144

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Height Above Flood Stage for Entire Period of Record Height Above FS Total Occurence Percent of Crest Occurrence Cumulative Total Flood Occurrence Percent of Floods above Listed Value 9 ft to 10 ft 53 36.8 9 ft or above 144 100.0 10 ft to 11 ft 33 22.9 10 ft or above 91 63.2 11 ft to 12 ft 23 16.0 11 ft or above 58 40.3 12 ft to 13 ft 14 9.7 12 ft or above 35 24.3 13 ft to 14 ft 9 6.2 13 ft or above 21 14.6 14 ft to 15 ft 3 2.1 14 ft or above 12 8.3 15 ft to 16 ft 3 2.1 15 ft or above 9 6.2 16 ft to 17 ft 2 1.4 16 ft or above 6 4.2 17 ft to 18 ft 0 0.0 17 ft or above 4 2.8 18 ft to 19 ft 1 0.7 18 ft or above 4 2.8 19 ft to 20 ft 1 0.7 19 ft or above 3 2.1 20 ft to 21 ft 0 0.0 20 ft or above 2 1.4 21 ft to 22 ft 2 1.4 21 ft or above 2 1.4

Height Above Flood Stage After Datum Change Height Above FS Total Occurence Percent of Crest Occurrence Cumulative Total Flood Occurrence Percent of Floods above Listed Value 9 ft to 10 ft 53 38.1 9 ft or above 139 100.0 10 ft to 11 ft 30 21.6 10 ft or above 86 61.9 11 ft to 12 ft 21 15.1 11 ft or above 56 40.3 12 ft to 13 ft 14 10.1 12 ft or above 35 25.2 13 ft to 14 ft 9 6.5 13 ft or above 21 15.1 14 ft to 15 ft 3 2.2 14 ft or above 12 8.6 15 ft to 16 ft 3 2.2 15 ft or above 9 6.5 16 ft to 17 ft 2 1.4 16 ft or above 6 4.3 17 ft to 18 ft 0 0.0 17 ft or above 4 2.9 18 ft to 19 ft 1 0.7 18 ft or above 4 2.9 19 ft to 20 ft 1 0.7 19 ft or above 3 2.2 20 ft to 21 ft 0 0.0 20 ft or above 2 1.4 21 ft to 22 ft 2 1.4 21 ft or above 2 1.4

Codes and description

C1|Crest information looks unreliable and incomplete and not used in frequency calculations. Some of the floods are based on current flood stage and nearby gage information.
C2|Crest information looks reliable despite potential problems. This data was used in frequency calculations.
C3|Crest height estimated by the USGS.
C4|Crest height is from the National Weather Service.
C5|Crest height affected by backwater.
C6|Crest occurred at a previous flood stage that is lower than the current flood stage. The crests below the new flood stage are not used in flood frequency calculations.
C7|Crest from USGS yearly peak and/or date is different than the crest we provide. In many cases MARFC uses crest based on backwater or ice effects.
C8|Crest month or day of occurrence has been estimated by The Middle Atlantic River Forecast Center usually based on nearby gage information.
C9|Crest date (day) in the month is unknown.
F1|Flow is an estimate.
F2|Flow affected by regulation or diversion and in some cases to an unknown degree.
F3|Flow effected by snow-melt, ice jam or debris jam break up.
F4|Flow affected by dam failure.
F5|Flow - All or part of the record affected by urbanization, mining, agricultural changes, channelization or other factors.
G1|Gage height at a different site and/or datum.
G2|Gage is not an official USGS gage with crests provided by the NWS. Crest information looks unreliable and incomplete and not used in flood frequency calculations.
G3|Gage datum changed during this year.
none,No code; Good Data

Updated: 08:09 AM Feb 08, 2013