Potomac River at Point of Rocks, Frederick County MD (PORM2)
Gage Location: Frederick County, MarylandSite Location: Frederick County, Maryland
Latitude: 39.274Longitude: -77.543Elevation: 200.63 ft. MSLDrainage Area: 9651 Sq. Mi.
Minor Stage: 16 ft. Moderate Stage: 20 ft.Major Stage: 25 ft.
First Flood: 1889-06-02Last Flood: 2012-10-31 Crest: 18.19 ft.Datum change: 1929-10-28Number of Floods: 114

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Height Above Flood Stage for Entire Period of Record
Height Above FSTotal OccurencePercent of Crest OccurrenceCumulative Total Flood OccurrencePercent of Floods above Listed Value
16 ft to 17 ft1815.816 ft or above 114100.0
17 ft to 18 ft1714.917 ft or above 9684.2
18 ft to 19 ft1614.018 ft or above 7969.3
19 ft to 20 ft1311.419 ft or above 6355.3
20 ft to 21 ft119.620 ft or above 5043.9
21 ft to 22 ft97.921 ft or above 3934.2
22 ft to 23 ft54.422 ft or above 3026.3
23 ft to 24 ft43.523 ft or above 2521.9
24 ft to 25 ft43.524 ft or above 2118.4
25 ft to 26 ft21.825 ft or above 1714.9
26 ft to 27 ft10.926 ft or above 1513.2
27 ft to 28 ft21.827 ft or above 1412.3
28 ft to 29 ft10.928 ft or above 1210.5
29 ft to 30 ft21.829 ft or above 119.6
30 ft to 31 ft00.030 ft or above 97.9
31 ft to 32 ft00.031 ft or above 97.9
32 ft to 33 ft10.932 ft or above 97.9
33 ft to 34 ft10.933 ft or above 87.0
34 ft to 35 ft00.034 ft or above 76.1
35 ft to 36 ft00.035 ft or above 76.1
36 ft to 37 ft32.636 ft or above 76.1
37 ft to 38 ft10.937 ft or above 43.5
38 ft to 39 ft00.038 ft or above 32.6
39 ft to 40 ft00.039 ft or above 32.6
40 ft to 41 ft21.840 ft or above 32.6
41 ft to 42 ft10.941 ft or above 10.9
Height Above Flood Stage After Datum Change
Height Above FSTotal OccurencePercent of Crest OccurrenceCumulative Total Flood OccurrencePercent of Floods above Listed Value
16 ft to 17 ft1516.116 ft or above 93100.0
17 ft to 18 ft1516.117 ft or above 7883.9
18 ft to 19 ft1111.818 ft or above 6367.7
19 ft to 20 ft1314.019 ft or above 5255.9
20 ft to 21 ft99.720 ft or above 3941.9
21 ft to 22 ft77.521 ft or above 3032.3
22 ft to 23 ft44.322 ft or above 2324.7
23 ft to 24 ft33.223 ft or above 1920.4
24 ft to 25 ft33.224 ft or above 1617.2
25 ft to 26 ft22.225 ft or above 1314.0
26 ft to 27 ft11.126 ft or above 1111.8
27 ft to 28 ft11.127 ft or above 1010.8
28 ft to 29 ft11.128 ft or above 99.7
29 ft to 30 ft11.129 ft or above 88.6
30 ft to 31 ft00.030 ft or above 77.5
31 ft to 32 ft00.031 ft or above 77.5
32 ft to 33 ft00.032 ft or above 77.5
33 ft to 34 ft11.133 ft or above 77.5
34 ft to 35 ft00.034 ft or above 66.5
35 ft to 36 ft00.035 ft or above 66.5
36 ft to 37 ft33.236 ft or above 66.5
37 ft to 38 ft11.137 ft or above 33.2
38 ft to 39 ft00.038 ft or above 22.2
39 ft to 40 ft00.039 ft or above 22.2
40 ft to 41 ft11.140 ft or above 22.2
41 ft to 42 ft11.141 ft or above 11.1