GEOLOGICAL SURVEY CIRCULAR 204 

FLOODS IN YOUGHIOGHENY AND 

KISKIMINETAS RIVER BASINS 

PENNSYLVANIA AND 

MARYLAND 

FREQUENCY AND MAGNITUDE 

Prepared by Water Resources Division 

UNITED STATES DEPARTMENT OF THE INTERIOR 

Oscar L. Chapman, Secretary 

GEOLOGICAL SURVEY 

W. E. Wrather, Director 

GEOLOGICAL SURVEY CffiCULAR 204 

FLOODS IN YOUGHIOGHENY AND KISKIMINETAS RIVER BASINS 

PENNSYLVANIA AND MARYLAND 

FREQUENCY AND MAGNITUDE 

Prepared by Water Resources Division 

Prepared in cooperation with the 

Pennsylvania State Department of Forests and Waters 

Washington, D. C.,1952 

Free on application to the Geological Survey, Washington 25, D. C. 

Page Introduction............................. 1 

Method................................... 1 

Records Available........................ 1 

Flood-frequency relationships............ 3 

Analysis of flood data................. 3 

Plotting positions..................... 3 

Adjustment to base periods............. 3 

Test for homogeneity................... 4 

Median flood ratios.................... 4 

Composite flood-frequency graphs....... 4 

Mean annual flood. • . . • . . . . . . • . . . • . . . . . . • . 9 

Computation of comparable means........ 9 

Mean annual flood versus drainage area. 9 

Application of flood data ................ 10 

Stage frequencies ...•••••••..•........... 11 

Gaging-station records ..•.........•...••• 11 

Kiskiminetas River basin: 

Stony Creek at Ferndale, Pa .•...•...• 12 

Conemaugh River at Seward ...•........ 12 

CONTENTS 

Page 

Gaging-station records--Continued 

Kiskiminetas River basin--Continued 

Conemaugh River at Tunnelton, Pa .•.. 13 

Kiskirninetas River at Avonmore ....... 14 

Little Conemaugh River at East 

Conemaugh........................ 15 

Blacklick Creek at Blacklick •••••.•.. 15 

Loyalhanna Creek at Kingston ......... 16 

Loyalhanna Creek at New Alexandria •.. 16 

Youghiogheny River basin: 

Youghiogheny River at Ohiopyle, Pa ... 17 

Youghiogheny River at Connellsville .. 18 

Youghiogheny River at Sutersville .... 19 

Casselman River at Markleton.......... 20 

Big Piney Run near Salisbury •...•.•.. 20 

Laurel Hill Creek at Ursina .......... 21 

Green Lick Run at Green Lick 

Reservoir........................ 22 

ILLUSTRATIONS 

Page 

Figure 1. Map showing location of gaging stations included in this report.................... 2 

2. Period of record of maximum annual peaks at gaging stations......................... 4 

3. Frequency of annual floods, all stations, period 1914-50 ••..• ·...•......•........... 7 

4. Frequency of annual floods, stations 4, 6, 9, 1q and 11, period 1914-50............ 8 

5. Frequency of annual floods, stations 4, 6, 9, 1q and 11, period 1884-1950.......... 8 

6. Variation of mean annual flood with drainage area ..........•.......•............... 10 

Table 1. 

2. 

3. 

TABLES 

Page 

Ratios to mean annual floods, ba~e period 1914-50.................................. 5 

Ratios to mean annual floods, base period 1884-1950................................ 6 

Computation of mean annual floods for period 1884-1950, Kiskiminetas and 

Youghiogheny River basins. . . . . . . • . . • . . • • . . . . . • . . . • . . . • . . . . . . . • • . . • . . . . . • . . . • . . . . 9 

iii 

FLOODS· IN YOUGIDOGHENY AND KISKIMINETAS RIVER BASINS 

PENNSYLVANIA AND MARYLAND 

FREQUENCY AND MAGNITUDE 

INTRODUCTION 

Engineers have long appreciated the fact 

that it is seldom economically sound to design hydraulic structures either for the maximum 

previous floods or for the computed maximum 

probable floods, unless failure of such structures involves loss of life or serious property damage. Such floods may not occur more often, on an average, than once in a hundred or possibly even several thousand years. In planning 

sound design for structures, such as culverts or bridge·s, which may involve flood frequencies 

of only 10 to 50 yr, the factors of economic~ 

and useful life of the structure should be con- sidered. 

In the past, records of streamflow have been so meager and of such short duration that litt~ 

reliable information could be obtained on the 

magnitude and frequency of floods in any particular region. As a result it has been the 

tendency of engineers to overdesign, often 

causing needless expenditure. 

The accumulation of reliable streamflow rec- ords over a relatively long period now permits 

satisfactory studies of flood probabilities in 

many regions. 

This report presents a method, based on actual flood data, for obtaining the magnitude 

and frequency of floods at any place in the 

watersheds of the Youghiogheny and Kiskiminetas 

River basins, an area comprising 3,651 sq mi 

in the upper Ohio River basin of western Pennsylvania and Maryland. 

The data contained in this report were com- piled and prepared for publication under a cooperative agreement on water resources investigations between the Pennsylvania Department of Forests and Waters, and the Water Re- sources Division, U. S. Geological Survey. 

J. W. Mangan directs the surface-water investigations in Pennsylvania for the U. S. Geological Survey. The data presented in this 

report were analyzed, and the text prepared, 

by the Pittsburgh suboffice, Max Noecker, engineer-in-charge, in collaboration with engineers of the Water Resources Division, U. S. Geological Survey, Washington, D. C. 

METHOD 

With streamflow records available for gaging 

stations located on various sized watersheds 

in the area, the study resolved itself into 

two parts: the determination of the floodfrequency characteristics of the region ex- pressed as a curve in terms of the ratio of a given flood to the mean annual flood, and the 

definition of a curve of mean annual flood ex- pressed as a function of the drainage area. With these known factors, it is possible to 

compute the magnitude-frequency relation of 

floods at any location in the region. 

RECORDS AVAILABLE 

All gaging-station records of sufficient 

length in the two river basins in which the 

peaks are not seriously affected by artificial 

regulation were used in this study. These 

stations all located in Pennsylvania, are: 

1. Stony Creek at Ferndale. 

2. Conemaugh River at Seward. 

3. Conemaugh River at Tunnelton. 

4. Kiskiminetas River at Avonmore. 

5. Little Conemaugh River at East Conemaug~ 

6. Blacklick Creek at Blacklick. 

7. Loyalhanna Creek at Kingston. 

8. Loyalhanna Creek at New Alexandria. 

9. Youghiogheny River at Ohiopyle. 

10. Youghiogheny River at Connellsville. 

11. Youghiogheny River at Sutersville. 

12. Casselman River at Markleton. 

13. Big Piney Run near Salisbury. 

14. Laurel Hill Creek at Ursina. 

15. Green Lick Run at Green Lick Reservoir. 

The locations of these stations are shown on the map presented as figure 1. 

l 
2 

PENNSYLVANIA 

-wEST' ViRGINIA 

( .... ..__ ________ \ 

I " 

j PENNSYLVANIA ( 

: _______ ./' 

FLOODS IN PENNSYLVANIA AND MARYLAND 

5 0 

Figure 1.--Map showing location of gaging stations included in this report. 

• • 

I 

• 

• 

20 Miles 
FLOOD-FREQUENCY RELATIONSHIPS 3 

Records for the following stations, operated 

presently or in the past within this area, have 

not been used in this report: 

Casselman River at Confluence, Pa., 

Laurel Hill Creek at Confluence, Pa., 

Youghiogheny River at Youghiogheny River 

Dam, Pa., ~asselman River at Grantsville, Md., 

Youghiogheny River at Oakland, Md., 

Youghiogheny River at Friendsville, Md. 

The first three stations listed were not 

used because they were affected by backwater 

for the greater part of the time. The records 

at the remaining stations were of too short 

duration to obtain satisfac~ory correlations 

with other stations necessary to extend them 

to the length of the base period. (.See Adjustment to base periods.) 

Whenever possible, gaging-station records were supplemented by historical flood data 

obtained prior to the systematic collection of 

stream-gaging records. 

Tabulations of the momentary peak stages 

and discharges at gaging stations during each 

"water year" of record are presented in the 

last section of this report. The water year 

extends from October 1 to September 30. 

FLOOD-FREQUENCY RELATIONSHIPS 

Analysis of flood data 

In developing flood-frequency relationships 

in this report, the annual-flood method was used. By this method each flood has been 

treated as an independent event, and ·only the 

maximum momentary discharge occurring in each 

water year of record was used. 

An objection often raised to the annualflood method is that it utilizes only one flood 

in each year and may discard one or more floods 

that occurred during the year that may be hig~ 

than some of the annual floods in other years. 

This objection is met by the partial-durationseries method in which all floods are listed 

above a selected base irrespective of the num- ber of floods occurring in any time period. 

This method involves the difficult·y that flood 

peaks occurring close together may not be independent events, and some arbitrary criterion 

must be set up for separating such peaks. 

The methods used for analysis are statistical, and a "complete" series such as the 

annual-flood series can be treated by a rigid 

statistical me~hod. 

The partial-duration-series method tells 

how often, on the average, a given flood will 

occur; the annual-flood method tells how often, on the average, it will occur as an annual 

peak. 

The following table1 gives the comparative 

values of the recurrence intervals, in years, 

by the two methods. Both methods give essen- tially the same results for recurrence intervals greater than 10 yr. 

1 Langbein, W. B., Annual floods and the 

partial-duration flood series, Amer. Geophys. 

Union, Trans., vol. 30, p. 879, 1949. · 

Annual floods 

1.16 

1.58 

2.00 

2.5::1: 

5.52 

10.5 

20.5 

50.5 

100.5 

Partial-duration-series 

0.5 

1.0 

1.45 

2.0 

5.0 

10 

20 

50 

100 

Plotting positions 

In analyzing the re-lation between frequency 

and magnitude of floods, the discharges were arranged by number in order of magnitude. 

Appropriate recurrence intervals were then 

assigned to each flood, depending upon the 

order number, the period of record, and any 

additional historical information indicating 

the frequency of recurrence. 

Recurrence intervals were computed from the 

formula (li+l)/M, where~ equals number of years 

of record and M equals the order of relative 

magnitude of the event beginning with the highest as one. In the case of a historical flood, 

N is the number of years during which it is 

known that the flood was of the order assigned. 

This formula, adopted by the Geological Survey, 

is simple to compute, is applicable both to 

annual-flood data and the partial-duration 

series, and gives results acceptably in con- formance with some of the latest theories. 

Annual floods were plotted on a special form2 developed for analysis of flood frequencies by the theory of extreme values.3 On the 

basis of this theory the discharge at a recur- rence interval of 2.33 yr is the same as the 

arithmetical mean of an infinitely long series 

of annual floods and is known as the "mean 

annual flood." As generally is done with relatively short series, such as are treated here, 

the value of the discharge at a recurrence interval of 2.33 yr has been picked graphically 

from a flood-frequency curve and used as the mean annual flood. 

Adjustment to base periods 

Figure 2 shows graphically the length of 

usable records in the two basins. In order to 

combine records, it is necessary for them to 

be on the same time basis. The longer the 

time basis, the more reliable is the resulting frequency curve. The longest continuous rec- ord, Youghiogheny River at Ohiopyle (Confluence), 

Pa., began in 1873; the next longest, Kiskiminetas River at Avonmore, Pa., began in 1884. 

The objective of this study was to obtain a composite frequency curve for the 67-yr period, 

·1884-1950. The procedure adopted, using all 

available data, was to compute the annualflood figures for years of missing record for 

all stations. After computing them, they were not used directly as peak discharges for those 

years but were used indirectly so as to obtain 

values for the mean annual flood based on a 

2 Powell, R. W., A simple method of estimating flood frequency, Civil Eng.,pp.l05-l06,. 

Feb. 1943. 

3 Gumbel, E. J., Floods estimated by the 

probability methcd, Eng. News-Record, June 14, 

1945. 
4 FLOODS IN PENNSYLVANIA AND MARYLAND 

Reference no. 

2 

1880 1890 1900 1910 1920 1930 

-------- -------------- -------- ------------

1940 1950 

3 ,__ ____ ------- ------ -------------- ------

4 

5 f------------------r-------

6 ----r--------r-------1--- ___ ..._ ____ -1------+------+-----i 

7 1------------------ ------ r-------1-------r---

8 1-----1------- r-------t-------1----- --~---

9 

10 f---- ----- II I r----1-------1------+------+------+------+-----+-· 

12 1-----1-------1--------------

13 ----r------- ------ ------- ------- -------t- -----+-----~ 

14 f----- ------- ------ ------

15 ,__ ____ ------r-------1-------1-------t----- -o~------+-----~ 

Figure 2.--Period of record of maximum annual peaks at gaging stations. 

uniform time period and the correct order num- bers in the base period for the actual known 

peaks. 

In this report it did not appear feasible 

to fill in or extend all records back to 1884. 

Only five records, those for Avonmore, Blacklick, Ohiopyle, Connellsville, and Sutersville, were used for the period 1884-1950. All others were used for the period 1914-50. The initial 

procedure was to work up composite frequency curves for all stations for the base period 

1914-50, the five long-term stations for the 

base period 1884-1950, a~d the five long-term 

stations for the shorter period 1914-50. 

Test for homogeneity 

A test for homogeneity was applied to the 

individual station records in order to assure that all records represent part of a region 

having uniform frequency characteristics. 

This is a statistical test applied to the 

slopes of the individual frequency graphs to 

determine whether deviations from an average 

slope are such as may be due to chance alone. 

The graphs were those for all stations for 

the 1914-50 period and the five long-term stations for the 1884-1950 period. The graphs were drawn using only peaks of actual record, 

with order numbers based on a complete listing as described in the prece.ding section. The 

test showed all records to be homogeneous for 

both base periods. 

Median flood-ratios 

In order to compare floods at different 

stations and combine them to define composite 

relationships, it was necessary to convert 

them to a dimensionless basis. This was done 

by expressing each flood as a ratio to the mean annual flood for the particular station, 

derived for a definite base period.· The mean annual floods_for the base periods were determined from the individual frequency graphs described in the preceding section. 

Tables 1 and 2 list by order number and 

station the peak floods of only those years 

for which there is actual record, expressed as a ratio to the mean annual flood. For the 

period 1914-50, table 1 shows the medians for 

each order of flood computed for all stations 

and for the five stations with long-term rec- ord. In table 2, medians were computed for 

each order of flood for the 67-yr stations. 

Composite flood-frequency graphs 

In figures 3 to 5 the median ratios from 

tables 1 and 2 were plotted against the recur- rence intervals for the corresponding order 

numbers. Average frequency curves were drawn. 

It will be noted that the composite curve for 

all stations, 1914-50 (fig. 3), is identical 

with that for the five index stations, 1914-50 

(fig. 4). For this reason the long-term com- posite frequency curve (fig. 5), as defined 

by the five index stations, can be taken to 

represent the frequencies for the period 1884-

1950 for all stations. If the curves of fig- ures 3 and 4 had not coincided, it would have 

beem necessary to compute a new curve from 

the curve of figure 5 by ratios representing 

the differences between the first two curves ~t specified recurrence intervals. 
Table 1.-- Ratios to mean annual floods, base period 1914-50 

RecurOrder Station no. renee no. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 interva 

1 5.36 4. 74 4.40 4.61 4. 5"0 3.50 4.19 3.12 2.94 2.62 3.20 4.06 2.12 5.00 38.0 

2 2.30 1. 74 1. 74 1.89 1. 87 2.16 3.08 2.67 2.07 2.20 3.87 1.94 2.ll 19.0 

3 2.17 1.84 1.64 1. 70 1.89 2.06 2.02 2.04 2.04 3.26 1. 67 1.95 12.7 

4 2.05 1.59 1.56 1. 61 1.55 1.54 l. 75 1.54 1. 67 1.34 1.88 9.50 

5 1.93 1.50 1.50 1. 57 1.52 1.54 1.59 1.37 1.45 1. 79 1.24 1.86 7.60 

6 1.91 1.48 1.35 1.50 1.45 1.40 1.54 1.45 1. 75 1.23 1.81 6.33 

7 1.56 1.39 1.31 1.33 1.36 1.35 1.38 1.52 1.45 1.23 5.43 

8 1.52 1.25 1.30 1.26 1.31 1.34 1.42 1.30 1.40 1.20 4.75 

9 1.37 1.25 1.20 1.30 1.26 1.23 1.33 1.30 1.37 1.17 1.19 4.22 

.10 1.32 1.24 1.18 1.30 1.17 1.27 1.28 1.18 1.42 1.16 3.80 

11 1.24 1.16 1.20 . 1.16 1..24 1.14 1.21 1.16 1.17 1.16 3.45 

12 1.15 1.15 1.19. t:22 1.12 1.12 1.22 1.16 3.17 

13 1.13 1.19 1.24 1.11 1.17 1.10 1.12 1.19 1.06 1.06 2.92 

14 1.10 1.06 1.06 1.11 1.04 1.10 1.12 1.11 1.03 1.01 2.71 

15 1.00 1.11 1.06 1.05 1.06 1.09 1.06 .991 1.03 .993 2.53 

16 .936 1.07 1.03 .946 1.02 .981 1.04 1.05 1.00 2.38 

17 .927 1.01 .991 .919 .985 .981 1.03 1.04 1.00 2.24 

18 .895 .988 1.00 .965 .905 .970 .965 .922 .964 2.11 

19 .851 .958 .919 .995 .939 .878 .933 .955 .887 .913 .909 .950 2.00 

20 .840 .910 .939 .913 .902 .948 .8'85 .857 .899 1.90 

21 .818 .893 .928 .870 .817 .824 .897 .886 .885 .835 .826 .887 1.81 

22 .755 .893 .846 .824 .897 .886 .812 .835 .880 .929 1. 73 

23 . 755 . 795 .803 .776 .. 894; .B23 .875 .810 .806 .835 .854 .914 1. 65 

24 .755 . 767 ':776 .793 .871 .806 .833 .751 829 1. 58 

25 .741 • 752 .709 .793 .844 . 781 .810 .779 1.52 

26 . 709 .666 . 743 .814 . 781 . 738 .810 .755 1.46 

27 .662 .695 . 726 . 728 .666 .712 .814 . 738 .810 .738 1.41 

28 .649 .695 .645 . 703 . 752 .785 .598 .687 .771 1.36 

29 .649 .671 .645 .662 .724 .785 .664 .682 1.31 

30 .636 . 710 .625 .662 . 757 .602 . 780 .592 .641 .664 1.27 

31 .624 .676 .625 .738 .683 .780 .641 .654 1.23 

32 .624 .660 .605 .670 .594 . 736 . 639 .621 1.19 

33' .611 .574 .643 ... 567 . 715 .579 .729 .598 .621 1.15 

34 .525 . 5§_§_ .618 .549 .514 .688 .687 .466 .573 1.12 

35 .478 .512 - .459 .632 .563 .-680 t--· .489 -~ 

~-~-

36 .453 .526 .543 .495 .459 .606 .555 .594 ".445 .447 .546 1.06 

37 .399 .455 .493 .472 .477 .419 .635 .530 .495 .571 .427 .450 1.03 

All Stations 

Number Median 

of itemf 

14 4.12 

13 2.11 

12 1.98 

11 1.59 

12 1.53 

11 1.48 

10 1.37 

10 1.30 

11 1.26 

10 1.26 

10 1.16 

8 1.16 

10 1.12 

10 1.08 

10 1.06 

9 1.02 

9 .991 

9 .965 

12 .926 

9 .902 

12 .878 

10 .863 

12 .816 

9 .793 

8 . 780 

8 . 749 

10 .727 

9 .695 

8 .668 

10 .652 

8 .665 

8 .632 

9 .611 

9 .573 

---, .!:>.L<::: 

11 .526 

12 .474 

Stations 

4, 6. 9 10. 11 

Number Median 

of items 

5 3.12 

5 2.07 

4 2.03 

4 l. 58 

5 1.54 

4 1.45 

4 1.36 

5 1.30 

5 1.30 

5 1.27 

5 1.16 

3 1.15 

4 1.14 

3 1.06 

3 1.06 

4 1.02 

5 .991 

4 .968 

4 .936 

5 .913 

5 .886 

5 .886 

5 .810 

4 .791 

4 .766 

4 . 760 

4 .732 

2 .698 

2 .684 

4 .668 

4 .680 

4 .632 

4 .611 

3 .586 ----s-~- r---_--;~ 

4 .549 

5 .495 

~ 

t"i 

0 

8 

~ 

~ g 

g{ 

0 

....:: 

::u 

t,tj 

t"i 

~ 

t-3 

H 

0 

~ ::X:: 

H 

1-cJ 

CIJ 

\Jl 
6 FLOODS IN PENNSYLVANIA AND MARYLAND 

Table 2.--Ratios to mean annual floods, base period 1884-1950 

Order Station no. Number Recurrence no. 4 6 9 10 11 of items Median interval 

1 4.40 4.31 2.69 2.60 2.50 5 2.69 a78 

2 2.35 3.78 2.66 2.36 2.50 5 2.50 b39 

3 2.10 2.12 2.31 2.11 1.97 5 2.11 22.7 

4 1. 98 2.26 1.97 3 1.98 17.0 

5 1.93 1.93 1.85 1. 95 4 1.93 13.6 

6 1.86 1. 78 2 1.82 11.3 

7 . 1. 74 1. 79 1.63 1. 79 1. 73 5 1. 74 9. 71 

8 1.65 1.62 1.63 1.72 1.62 5 1.63 8.50 

9 1.54 1.55 1.52 3 1.54 7.56 

10 1.54 1.44 1.53 1.48 4 1.50 6.80 

11 1.51 1.38 1.30 3 1.38 6.18 

12 1.50 1.33 1.40 1.30 4 1.36 5.67 

13 1.48 1.44 1.32 1.37 4 1.40 5.23 

14 1.35 1.44 1.31 1.37 1.28 5 1.35 4.86 

15 1.31 1.41 1.30 1.35 4 1.33 4.53 

16 1.26 1.34 1.28 1.31 4 L30 4.25 

17 1.25 1. 27 1.21 1.25 1. 24 5 1.25 4.00 

18 1.25 1.24 1.20 1.25 1.24 5 1.24 3. 78 

19 1.22 1.24 1.19 1.18 1.22 5 1.22 3.58 

20 1.18 1.24 1.18 1.20 4 1.19 3.40 

21 1.16 1.18 1.12 1.10 4 1.14 3.24 

22 1.15 1.19 1.15 1.12 1.10 5 1.15 3.09 

23 1.19 1.11 1.09 1.06 4 1.10 2.96 

24 1.08 1.17 1.10 1.07 1.06 5 1.08 2.83 

25 1.14 1.07 2 1.10 2.72 

26 1.06 1.12 1.06 1.05 4 1.06 2.62 

27 1.02 1.02 1.04 1.05 4 1.03 2.52 

28 1.04 1.02 1.01 1.02 1.04 5 1.02 2.43 

29 .997 1.01 2 1.00 2.34 

30 1.02 .992 .987 1.00 4 .996 2.27 

31 1.01 1.01 .990 3 1.01 2.19 

32 1.00 .950 .967 1.01 .982 5 .982 2.12 

33 .926 .925 .967 .961 4 .944 2.06 

34 .919 .900 .954 .948 4 .934 2.00 

35 .910 .900 .898 .927 .940 5 .910 1.94 

36 .871 .912 2 .892 1.89 

37 .893 . 833 .875 .868 .905 5 .875 1.84 

38 .893 .875 .868 .905 4 .884 1. 79 

39 .876 .8ll .875 .854 .905 5 .875 1. 74 

40 .852 .875 .854 .878 4 .864 1. 70 

41 .819 .788 .849 3 .819 1.66 

42 .819 .788 .836 .843 .845 5 .836 1.62 

43 .776 .826 .828 3 .826 1.58 

44 .767 .743 .787 .798 .820 5 .787 1.55 

45 • 787 .820 2 .804 1.51 

46 .752 .679 .774 . 787 4 .763 1.48 

47 .774 .784 .775 3 .775 1.45 

48 .726 .761 .784 .770 4 .766 1.42 

49 .638 .754 .742 .770 4 .748 1.39 

50 .638 .751 .717 3 .717 1.36 

51 .710 .618 .728 . 705 4 .708 1.33 

52 .710 .618 .725 .691 .705 5 • 705 1.31 

53 ,.618 .725 .691 3 .691 1.28 

54 .676 .599 . 702 .650 4 .663 1.26 

55 .660 .599 . 702 .6~6 .650 5 .660 1.24 

56 .660 .580 .641 3 .641 1.21 

57 .643 .598 2 .620 1.19 

58 .600 .652 .604 .575 4 .602 1.17 

59 .600 .543 .636 .593 4 .596 1.15 

60 .586 .526 .590 .568 4 .577 1.13 

61 .491 .616 .552 3 .552 1.11 

62 .543 .593 2 .568 1.10 

63 .514 .474 .559 .538 4 .526 1.08 

64 .507 .537 .530 3 .530 1.06 

65 .493 .457 .548 .525 .492 5 .493 1.05 

66 .538 .469 .472 3 .472 1.03 

67 .419 .518 .469 .465 4 .467 1.01 

a Highest since 1874. 

b Second highest since 1874. 
4.40 

4.00 

3.60 

0 

0 3.20 0 

..J 

LL 

..J 

~ 2.80 :::l 

z 

z 

~ 

z 2.40 ~ 

LLJ 

~ 

0 

t0 

t-

~ 

a:: 

2.00 

1.60 

1.20 

.80 

.40 

1.01 

FLOOD-FREQUENCY RELATIONSHIPS 7 

! 

0 

! 

I 

I 

I 

I 

' I v 

I 

I v 

I 

I 

I v 

I / 

l 

I v ! .... v 

I ~ (U 

I ~ ~ 

I 

I 9-~ 

~ l.P-6" 

/ ! ~ .-v 

~ ~ I 

~ I 

~ i 

I 

1.1 1.2 t.3 t.4L5 2 3 4 5 · 6 1 a 9 10 20 30 40 50 

RECURRENCE INTERVAL, IN YEARS 

Figure 3.--Frequency of annual floods, all stations, period 1914-50. 
8 

3.20 

0 

0 2.80 

0 

....J 

lL.. 

~ 2.40 :::::> 

z 

z 

<( 

,z 

<( 

w 

~ 

0 

..... 

0 

..... 

<( 

a::: 

2.00 

1.60 

1.20 t 

.80 

~0 

LOI 

FLOODS IN PENNSYLVANIA AND MARYLAND 

I 0 

I 

I 

! 

I 

I v 

I 

I / 

I v I 

I 

! 0 ~ 

I / I 

I 

I ...... v 

i _,R1 0 

I ~ ~ I )Y6 I .9-

~ ..e15 

~ I 

~ ~ ~ I ~ ~ I 

~ I 

I 

1.1 1.2 1.3 14 1.5 2 3 4 5 6 7 8 9 10 20 30 40 50 

RECURRENCE INTERVAL,IN YEARS 

Figure 4.--Frequency of annual floods, stations 4, 6 1 9, 10, and 11, ~eriod 1914-50. 

2.80 

0 2.40 

0 

g 

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1.01 1.1 1.2 l3 1.4 1.5 2 3 4 5 6 7 8 9 10 20 30 40 50 

RECURRENCE INTERVAL, IN YEARS 

100 

Figure 5.--Frequency of annual floods, stations 4, 6, 9, 10, and 11, period 1884-1950. 
FLOODS IN. PENNSYLVANIA AND MARYLAND 9 

MEAN ANNUAL·FLOOD 

Computation of comparable means 

The value of the mean annual flood will vary 

with the length of the record from which it is 

derived and will be dissimilar for different 

periods of record even though the same number 

of ye~rs is being considered. In analyzing 

the relation between mean annual flood and 

drainage area, it is necessary to use values 

for the mean annual flood that are based on the same time period. It is also desirable 

to make this time period as long as possible. 

In this study the observed·mean annual 

floods, adjusted t·o the 67-yr period 1884-1950,. were used in the development of the mean annual 

flood-drainage area relation. The average ratio 

of the 67-yr to the 37-yr mean annual floods, 

obtained from the five index stations (table 3~ 

was 1.076. Values of the 37-yr mean annual 

floods for the other stations were adjusted 

to the 67-yr values by applying the coefficient 

1.076. 

Mean annual flood versus drainage area 

The adjusted values for mean annual floods were plotted against drainage areas in figure 6 

and an average curve was obtained. The corre- lation of mean annual floods to drainage areas alone is remarkably consistent. 

An attempt was made to investigate the re- lation between mean annual floods and physical 

characteristics, other than size of drainage 

·area, that might explain the spread of some points from the average curve. There was not 

conclusive evidence to indicate that other 

variables were sufficiently effective to influence the results of the present study. 

There are a few points that vary as much as 15 to 20 percent from the average curve as drawn, but these results are considered acceptable. OWing to the chance elements involved 

and depending upon the length of record, there 

is an expected variation in the mean annual 

flood that can be computed by statistical 

methods for any desired confidence interval. 

A 95 percent confidence interval was used. 

Table 3.--Computation of mean annual floods for period 1B84-1950 Kiskiminetas and Youghiogheny 

River basins 

(All gaging stations are located in Pennsylvania} 

I II 

Drain- Mean annual Mean annual Ratio No. Station age flood (cfs} flood (cfs} IIti area 1914-50 1884-1950 

4 Kiskiminetas River at Avonmore-------------- - 42,000 42,000 1.000 

6 Blacklick Creek at Blacklick---------------- - 11,500 12,000 1.043 

9 Youghiogheny River at Ohiopy~e -------------- - 26,300 30,500 1.160 

10 Youghiogheny River at Connellsville--------- - 31,500 35,600 1.130 

11 Youghiogheny River at Sutersville----------- - 38,200 40,000 1.047 

Avera~e--------------------------------~ ----------- ------------- ------------- 1.076 

1 Stony Creek at Ferndale--------------------- 451 11,000 11,800 

2 Conemaugh River at Seward ------------------- 715 . 19,000 20,400 

3 Conemaugh River at Tunnelton---------------- 1,358 34,000 36,600 

4 Kiskiminetas River at Avonmore-------------- 1,723 42,000 42,000 

5 Little Conemaugh River at East Conemaugh---- 183 6,250 6,120 

6 Blacklick Creek at Blacklick---------------- 390 11,500 12,000 

7 Loyalhanna Creek at Kingston---------------- 168 6,000 6,460 

8 Loyalhanna· Creek at New Alexandria---------- 265 7,400 7,960 

9 Youghiogheny River at Ohiopyle-------------- 1,062 26,300 30,500 

10 Youghiogheny River at Connellsville--------- 1,326 31,500 35,600 

11 Youghiogheny River at Sutersville~---------- 1,715 38,200 40,000 

12 Casselman River at Markleton---------------- 382 11,200 12,100 

13 Big Piney Run near Salisbury-----------J---- 24.5 1,060 1,140 

14 Laurel Hill Creek at Ursina----------------- 121 4,850 5,220 

15 Green Lick Run at Green Lick Reservoir------ 3.07 280 301 
10 FLOODS IN PENNSYLVANIA AND MARYLAND 

1-

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100,000 

10,000 

1000 

800 

600 

400 

200 

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DRAINAGE AREA, IN SQUARE MILES 

Figure 6.--Variation of mean annual flood with drainage area. 

The significance of this is that 95 percent of 

the time the mean annual flood, on the basis 

of chance alone, can be expected to fall within the computed limits. The deviations from 

the average curve are within these limits and are therefore considered satisfactory. 

APPLICATION OF FLOOD DATA 

Two basic curves have been developed from 

the available data that can be used to determine the frequency relationship of any area, 

gaged or ungage~ in the Youghiogheny and 

Kiskiminetas River basins. 

Figure 5 represents the general frequency 

relation, expressed as a ratio to the mean annual flood, at any point within the two 

basins. 

Figure 6 represents a satisfactory relation 

between drainage area and mean annual flood 

for any point within the two basins with a drainage area greater than 3 sq mi. 

These curves should not be extrapolated 

beyond the limits of the available data be- cause this procedure could lead to serious error. 

Only two station records were available on drainage areas less than 100 sq mi. The size 

of drainage area generally has not been found 

to have any effect on the characteristics of 

the frequency curve. More small-area records 

would be desirable in the definition of mean annual floods. However, the consistency of 

the plotting of points on figure 6 gives some confidence in the lower part of the curve. 

• The results are applicable to unregulated 

conditions only. Some of the stations used are slightly affected by regulation. However, 

it is likely that the annual peak discharges 

for these stations have not been materially 

affected. Other stations have been materially 

affected in recent years, but the peak discharges for these years were not used. 

To determine the frequency curve at a desired site, enter the ~urve of figure 6 with 

the known drainage area and obtain the value 

of the mean annual flood. Then from the curve of figure 3, select values at several recur- rence intervals of the ratio to mean annual 

flood. These ratios when multiplied by the mean annual flood will give the values of peak 

discharge that can be plotted against the cor- responding recurrence intervals to define the 

desired frequency curve. 

To illustrate the use of the data, let us suppose that it is desired to determine the 

flood frequency curve for an ungaged site, 

within this area, that has a drainage area of 

100 sq mi. 

From figure 6, it is found that the mean annual flood on a watershed of 100 sq mi is 

4,200 cfs. 
GAGING-STATION RECORDS 11 

From figure 5, the values of ratio to mean annual flood have been selected arbitrarily 

at recurrence intervals of: 

1.1, 1.5, 2.33, 5, 10, 25, and 50 yr. 

These ratios were found to be: 

0,55, 0.77, 1.00, 1.38, 1.71, 2.16, and 

2.50, respectively. 

These values when multiplied by the mean annual flood, 4,200 cfs, give discharges of: 

2,310, 3,230, 4,200, 5,800, 7,180, 9,Q70, 

and 10,500 cfs, respectively. 

The frequency curve for the site may be 

obtained by plotting these discharges against 

the corresponding recurrence intervals. 

If it is desired to determine only the discharge for a specific recurrence interval for 

the site, the frequency curve need not be 

plotted. For example, if the discharge for a 25-yr flood is required, it is necessary only 

to determine the mean annual flood (4,200 cfs) 

and the ratio for the 25-yr recurrence interval ~.16). By multiplying these two factors, the 

25-yr flood is found to be 9,070 cfs. 

STAGE FREQUENCIES 

Information on stage frequency rather than 

discharge may sometimes be desired. Where the 

relation between stage and discharge is known, 

it is possible to convert from a dischargefrequency curve to a stage-frequency curve. This relation is usually known only at gagingstation sites, and no general stage-frequency 

relationships can be formulated for a region. 

Although for Pennsylvania streams the re- lation at high stages between stage and.discharge at any particular site is fairly stable, 

there is enough change so that current information should always be utilized. For this reason no attempt has been made to furnish 

information on stage frequencies in this re- port, except that gage heights are shown for 

annual floods at the individual gaging stations. The necessary data, whereby stage 

frequencies may be determined at any gaging- station site in these basins, is on file at 

the offices of the U. S. Geological Survey in 

Harrisburg and Pittsburgh, Pa. 

GAGING-STATION RECORDS 

Annual-peak gage heights and discharges at 

gaging stations used in this report have been 

tabulated in this section. 

The annual peaks listed were the highest 

momentary peaks in each water year, which includes the period October 1 to September 30. 

The water year was used rather than the calendar year because September and October are usually months of low flow; hence the use of 

the water year tends to eliminate any influ- ence tbat one annual flood might have upon 

another. Although the maximum flood in each 

water year is listed,· the date shown is for 

the calendar year in which the event occurred. 

Gage heights represent the water level in 

feet above an arbitrary datum that is referenced to local benchmarks at the gage. At 

most stations the gage datum has been tied into the level net of the Coast and Geodetic 

Survey, and for these stations the mean-sea- level elevation of the datum of gage is given 

under "Gage" in descriptive material. The 

gage heights were generally obtained from 

water-stage recorder charts, recorded flood 

marks, or graphs based on gage readings by an observer. 

Peak discharges are listed in cubic feet 

per second. This term in abbreviated form is 

designated in the tables and station records as "cfs." Peak discharges are computed directly from the peak gage heights by means of 

the stage-discharge relation. 

Before data from these stations were used, 

the stage-discharge relation during the period 

of record at each gaging station was reviewed 

and records were revised where necessary .. Most of the.se revisions were based on data 

obtained after the discharges were already 

published. For the most part, the changes were made in the interests of consistency in 

this report. Some records involve significant differences with already published figures. 

These major revisions are being published in 

the water-supply papers and will supersede 

earlier figures. Where no such revisions are made, it can be assumed that figures originally 

published can be used without loss of accuracy. 

Source of the data is indicated under 

"Remarks" for records other than those collected 

by the U. S. Geological Survey. 
12 FLOODS IN PENNSYLVANIA AND MARYLAND 

Kiskiminetas River basin 1 

(1) Stony Creek at Ferndale, Pa. 

Location.--Lat 40°17 1 1011 , long. 78°55 1 10", at highway bridge at Ferndale, Cambria County, 0.4 mile 

downstream from Bens Creek, 1.2 miles upstream from Johnstown city limit, and 5.2 m:+les upstream 

from confluence with Little Conemaugh River. 

Drainage area.--451 sq mi; 467 sq mi at site in Johnstown prior to 1939. 

Gage.--Nonrecording gage at Johnstown, July 1913 to March 1936; datum of gage 1,154.0 ft above mean sea level. Nonrecording gage at Ferndale, December 1938 to May 1940 and recording gage 

thereafter; datum of gage 1,183.84 ft above mean sea level. 

Stage-discharge relation.--Defined by current-meter measurements below 12,000 cfs and extended to 

59,000 cfs on basis of slope-area and contracted-opening measurements. 

Remarks.--Regulation by mine pumpage and by reservoirs above station, the five largest of which 

have a combined capacity of 1,788,000,000 cu ft. Some diversion from Quemahaning Reservoir to 

Cambria plarit of Bethlehem Steel Co., and from Mill Creek, Dalton Run, and North Fork Bens 

Creek Reservoirs for water supply of city of Johnstown. Annual peak discharges not materially 

affected by regulation or diversion. 

Records from July 1913 to March 1936, and December 1938 to September 1941 in reports of 

Pennsylvania Department of Forests and Waters. Annual flood of 1937 from crest elevation 

furnished.by city engineer of Johnstown. Annual flood for 1938 computed from U. S. Weather 

Bureau gage records. 

Date 

1914, Mar. 

1915, Jan. 

1916, Mar. 

1917, Mar. 

1918, Feb. 

1919, May 

30------

7-------

28------

12------

26------

10-------

Gage 

~eight 

\feet) 

7.85 

10.70 

11.30 

14.00 

12.7 

8.15 

Annual flood stages and discharges 

Discharge 

(cfs) 

------------- 5,260 

------------- 9,360 

------------- 10,300 

------------- 15,100 

------------- 12,700 

------------- 5,780 

Date 

1933, Mar. 15------

1934, Jan. 7-------

1935, Aug. 2-------

1936, Mar. 18------

1937, Apr. 26------

1937, Oct. 28------

Gage 

height 

(feet) 

11.72 

8.9 

9.26 

30.26 

18.8 

10.0 

Discharge 

(cfs) 

------------ 11,000 

------------ 6,720 

------------ 7,280 

------------ 59,000 

------------ 25,300 

------------ 8,300 

1920, Mar. 12------ 11.2 ------------- 10,200 Change in site and datum 

1921, Mar. 3------- 8.98 ------------- 6,860 1939, Feb. 3------- 8 8 ------------ 9,240 

1921, Nov. 28------ 13.7 ------------- 14,500 1940, Mar. 31----;...- 13.3 ------------ 23,900 

1923, Feb. 2------- 7.1 ------------- 4,390 1941, June 5------- 12.27 ------------ 22,600 

1924, Mar. 29------ 16.9 ------------- 21,000 1942, Apr. 9------- 8.72 ------------ 9,000. 

1925, Feb. 11------ 10.0 ------------- 8;300 1942, Dec. 30------ 11.07 ------------ 17,200 

1926, Feb. 23------ 10.0 ------------- 8,300 1944, Mar. 17------ 7.90 ------------ 7,140 

1927, Jan. 22------ 10.96 ------------- 9,840 1945, Mar. 6------- 11.97 ------------ 21,200 

1928, May 1-------- 13.23 ------------- 13,600 1946, June 2------- 10.95 ------------ 16,700 

1929, Feb. 26------ 9.15 ------------- 7,140 1947, June 8------- 6.85 ------------ 4,980 

1930, Feb. 25------ 9.90 ------------- 8,150 1948, Apr. 14------ 9.78 ------------ 12,100 

1931, Apr. 4--'----- 9.02 ------------- 6,860 1949, Jan. 26------ 8.15 ------------ 7,800 

1932, Apr. 1------- 9.1 ------------- 7,000 1950, Mar. 28------ 9_.90 ------------ 12,400 

(2) Conemaugh River at Seward, Pa. 

Location.--Lat 40°25'10 11 , long. 79°01'40", at highway bridge at Seward, Westmoreland County, 

2 miles downstream from Findley Run, and 9 miles northwest of Johnstown. 

Drainage area.--715 sq mi. 

Gage.--Reco~ding gage. Datum of gage is 1,075.64 ft above mean sea level, unadjusted. 

Stage-discharge relation.--Defined by current-meter measurements below 21,000 cfs and extended to 

90,000 cfs on basis of contracted-opening measurement. 

Historical data.--Flood of March 18, 1936; 90,000 cfs (gage height, 26.4 ft) from floodmarks. 

Remarks.--Regulation by steel mills and by several reservoirs above station, the eight largest of 

which have a combined capacity of 2,060,170,000 cu ft. Annual peak discharges not materially affected by regulation. 
Date 

1936, Mar. 18------ 26.4 

1939, Feb. 3------- 9.00 

1940, Mar. 31------ 15.22 

1941, June 5------- 13.15 

1942, Apr. 9------- 10.07 

1942 Dec. 30------ 12.70 

KISKIMINETAS RIVER BASIN 

(2) Conemaugh River at Seward, Pa.--continued 

Annual flood stages and discharges 

Discharge 

{cfs) 

------------ 90,000 

------------ 15,100 

------------ 35,000 

------------ 28,200 

------------ 18,200 

--:-----~---- 26 500 

(3} Conemaugh River 

Date 

1944, Mar. 17------

1945, Mar. 6-------

1946, June 2-------

1947, June 8 ------ 1948, Apr. 14------

1949, Jan. 26------

1950 Mar. 28------

at Tunnelton, Pa. 

8.39 

13.76 

11.27 

6.75 

11.04 

8.37 

10.80 

13 

Discharge 

(cfs) 

------------ 13,200 

------------ 30,200 

------------ 22,000 

------------ 8,650 

------------ 21,000 

------------ 13,200 

------------ 20 400 

Location.--Lat 40°27 1 15 11 , long. 79°23 130 11 , at highway bridge at Tunnelton, Indiana County, 0.9 mile 

downstream from Boatyard RUn, 3t miles southeast of Saltsburg, and 5.5 miles upstream from con- fluence with Loyalhanna. Creek •. 

Drainage area. --1 ,3_58 sq mi. 

Gage.--Nonrecording gage. Datum of gage is 844.64 ft above mean sea level, datum of 1929. 

~tage-discharge relation.--Defined by current-meter measurements throughout. 

Remarks.--Regu1ation by steel mills and by several reservoirs above station, the eight largest of 

which have a combined capacity of 2,060,170,000 cu ft. Annual peak discharges not materially 

affected by regulation. 

Date 

1940, Mar. 31------ 20.18 

1941, June 5------- 16.9 

1942, Apr. 10-'----- 15.3· 

1942, Dec. 30------ 19.6 

1944, Mar. 17------ 11.6 

1945 Mar. 7------- 21.0 

Annual flood stages and discharges 

Discharge 

(cfs) 

----------- 55,600 

----------- 42,300 

----------- 36;200 

----------- 53,10el 

----------- 22,800 

----------- 59 200 

Date 

1946, Jure 13--------

1947, June 8--------

1948, Apr. 14-------

1949, Jan. 27-------

1950, Mar. 28-------

14.6 

10 .• 1 

16.5 

10.6 

12.9 

Discharge 

(cfs) 

----------- 33,600 

----------- 17,900 

----------- 40,800 

----------- 19,500 

----------- 27,300 
14 FLOODS IN PENNSYLVANIA AND MARYLAND 

(4) Kiskiminetas River at Avonmore, Pa. 

Location.--Lat 40°32 1 05 11 , long. 79°27 1 55 11 , at highway bridge at Avonmore, Westmoreland County, 

1 mile above mouth of Long Run. 

Drainage area.--1,723 sq mi. 

Gage.--Nonrecording gage May 1907 to July 1937. Datum of gage is 805.64 ft above mean sea level. 

Stage-discharge relation.--Defined by current-meter measurements below 30,000 cfs and extended to 

185,000 cfs on basis of slope-area measurement. 

Remarks.--Regulation by steel mills, since 1942 by Loyalhanna Creek Reservoir and other reservoirs 

above station, the nine largest of which have a combined capacity of 2,108,300,000 cu ft. 

Annual peak discharges not materially affected by regulation. 

Records from May 1907 to September 1941 in reports of Pennsyl,vania Department of Forests 

and Waters. Records prior to May 1907 from Water Supply Commission of Pennsylvania, Water 

Resources Inventory Report, Part 8, Floods (computed from Signal Service and Weather Bureau 

gage readings at Saltsburg). Records after July 1937 computed on basis of record of recording 

gage at Vandergrift, drainage area 1,825 sq mi. 

Annual flood stages and discharges 

Discharge Discharge 

Date ( cfs) Date (cfs) 

1884, Feb. 6-------- 24.1 ---------- 52,900 1916, Mar. 22------- 20.0 --------- 37,500 

1885, Jan. 17------- 16.4 ·---------- 25,200 1917, Jan. 22------- 24.0 --------- 52,500 

1886, Jan. 5-------- 19.1 ---------- 34,400 1918, Feb. 20------- 22.0 --------- 44,500 

1886, Dec. 14------- 13.8 ---------- 17,600 1919, Jan. 2-------- 16.2 --------- 24,600 

1888, Aug. 21------- 31.8 ---------- 88,000 1919, Nov. 27------- -20.3 -------·-- 38,600 

1889, .June 1-------- 29.8 ---------- 78,000 1921, Jan. 23------- -15.6 --------- 22,800 

1890, Mar. 23------- 17.8 ---------- 29,800 1921, Nov. 29------- 24.65 --------- ·54,900 

1891, Feb. 17------- 30.4 ---------- 81,000 1923, May 13-------- 18.0 --------- 30,500 

1892, .Jan. 14------- 15.1 ---------- 21,300 1924, Mar. 30------- 24.0 --------- 52,500 

1893, Feb. 11------- 15.2 ---------- 21,600 1925, Feb. 12------- 17.8 --------- 29,800 

1894, May 20-------- 19.5 ---------- 35,800 1926, Sept. -6------- 18.5 --------- 32,200 

1895, Jan. 8-------- 19.8 ---------- 36,800 1927, Jan. 22------- 21.3 --------- 42,000 

1927, Oct. 20------- 25.1 --------- 56,900 

1902, Mar. 1-------- 26.4 ---------- 62,300 1929, Feb. 26------- 16.96 --------- 27,000 

1903, Mar. 1-------- 16.4 ---------- 25,200 1930, Feb. 25------- 23.3 --------- 49,700 

1904, Jan. 23------- 21.8 ---------- 43,800 1931, Apr. 4-------- 20.2 --------- 38,200 

1905, Mar. 8-------- 20.4 ---------- 38,900 1932, Apr. 1--------- 18.3 --------- 31,600 

1906, June 7-------- 19.1 ---------- 34,400 1933, Mar. 15------- 23.0 --------- 48,500 

1907, Mar. 14------- 33.8 ---------- 98,900 1934, Sept. 30------ 14.90 --------- 20,700 

1908, Mar. 19------- 30.8 ---------- 83,000 1935, Aug. 4-------- 18.6 -------4-- .32,600 

1909, Feb. 24------- 17.2 ---------- 27,700 1936, Mar. 18------- 47.2 --------- 185,000 

1910, Feb. 17------- 23.7 ---------- 51,300 1937, Apr. 26------- 28.8 --------- 73,100 

1911, Sept. 15------ 21.5 ---------- 42,800 1937, Dec. 18----------------------- 37,500 

1912, Mar. 21------- 28.0 ---------- 69,500 1939, Feb. 4------------------------ 28,400 

1913, Jan. 8-------- 22.2 ---------- 45,300 1940, Mar. 31----------------------- 62,800 

1914, Mar. 17------- 17.2 ---------- 27,700 1941, June 5----7------------------- 48,900 

1915 Feb. 2-------- 21.40 ---------- 42 400 
KISKIMINETAS RIVER BASIN 15 

(5) Little Conemaugh River at East Conemaugh, Pa. 

Location.--Lat 40°20 1 35", long. 78°53'05", at highway bridge at East Conemaugh, Cambria County, 

0.3 mile downstream from Clapboard Run and 2.5 miles upstream from confluence with Stony Creek. 

Drainage area.--183 sq mi. 

Gage.--Recording gage. Datum of gage is 1,207.92 ft above mean sea level (Corps of Engineers 

----oenchmark) • 

Stage-discharge relation.--Defined by current-meter measurements below 5,200 cfs and extended to 

29,000 cfs on basis of slope-area measurement. 

Historical data.--Flood of March 17, 18, 1936, 28,800 cfs by slope-area determination. 

Remarks.--Regulation by small reservoirs and diversion works above station. Annual peak discharges 

not materially affected by regulation. 

Date 

Gage 

height 

(feet) 

Annual flood stages and discharges 

Discharge 

(cfs) Date 

Gage 

height 

(feet) 

Discharge 

(cfs) 

1936, Mar. 17, 18---------------------- 28,800 1945, Mar. 6<------- 8.03 ------------ 9,350 

1946, June 2------- 6.29 ------------ 5,800 

1940, Mar. 30-------- 8.80 ------------- 11,800 1947, June 8------- 4.83 ------------ 2,950 

1941, June 5-------- 7.19 ------------- 7,530 1948, Apr. 14------ 6.47 ------------ 6,220 

1942, Apr. 9------·-·- 6. 77 ------------- 6,590 1949, July 12------ 5.36 ------------ 3,860 

1942, Dec. 30--------· 7.29 ------------- 7,410 1950, Mar. 28---,--- 6.22 ------------ 5,590 

1944, Mar. 17------- 6.06 ------------- 4,550 

(6) Blacklick Creek at Blacklick, Pa. 

Location.--Lat 40°28'25", long. 79°12'15", at highway bridge at Gratton, a quarter of a mile northwest of Blacklick, Indiana County, and three-quarters of a mile downstream from Two Lick Creek. 

Drainage area.--390 sq mi. 

Gage.--Nonrecording gage. Datum of gage is 945.94 i't above mean sea level (Pennsylvania State 

~ghway benchmark). 

Stage-discharge relation.--Defined by current-meter measurements below 18,000 cfs and extended to 

52,000 cfs on basis of slope-area determination. 

Remarks.--Records August 1904 to December 1905 and January 1907 to September 1941 in reports of 

Pennsylvania Department of Forests and Waters. 

1905, 

1905, 

1907, 

1908, 

1909, 

1910, 

1911, 

1912, 

1913, 

1914, 

1915, 

1915, 

1917, 

1918, 

1918, 

1920, 

1921, 

1921, 

1923, 

1924, 

1925, 

1926, 

1927, 

Date 

Mar. 21------

Dec. 3-------

Mar. 14------

Mar. 19------

Feb. 24------

Jan. 18------

Jan. 14------

Sept. 3------

Jan. 8-------

May 6--------

Jan. 7-------

0ct. 19------

Jan. 22------

Feb. 20------

0ct. 31------

June 17------

May 5--------

Nov. 29------

May 13-------

June 29------

Feb. 11------

Sept. 5------

Jan. 22------

Gage 

height 

(feet) 

8.6 

11.2 

15.4 

11.3 

8.8 

10.97 

10.2 

12.9 

10.5 

8.0 

10.72 

10.7 

11.3 

10.8 

7.9 

10.5 

7.3 

9.85 

9.5 

12.2 

7.2 

8.9 

9.40 

Annual flood stages and discharges 

Discharge 

(cfs) 

8,920 

16,900 

45,400 

17,300 

9,460 

16,100 

13,400 

25,500 

14,300 

7,420 

14,900 

14,900 

17,300 

15,300 

7,190 

14,300 

5,890 

12;200 

11,400 

21,500 

5,690 

9,730 

11,100 

1927, 

1929, 

1930, 

1931, 

1932' 

1933, 

1935, 

1936, 

1937, 

1937' 

1939, 

1940, 

1941, 

1942, 

1942, 

1944, 

1945, 

1946, 

1947, 

1948, 

1949, 

1950, 

Date 

Oct. 20------

Feb. 26------

Feb. 25------

Apr. 4-------

Apr. 1-------

Mar. 15------

May 10-------

Mar. 18------

Jan. 25------

Dec. 18------

Jan. 31------

Mar. 31------

June 5-------

Apr. 9-------

Dec. 30------

Mar. 17------

Mar. 6-------

June 13----.--

June 8-------

Apr. 12------

Jan. 24------

Ju1y 5-------

Gage 

height 

(feet) 

9.80 

8.10 

9.70 

9.30 

7.5 

9.28 

8.30 

15.88 

8.8 

10.3 

7.8 

11.5 

8.0 

9.01 

11.76 

8.1 

10.4 

11.65 

7.10 

10.7 

7.65 

7.90 

Discharge 

(cfs) 

12,200 

7,660 

11,900 

10,800 

6,310 

10,800 

8,150 

51,700 

9,460 

13,700 

.6, 960 

18,100 

7,420 

10,000 

19,500 

7,660 

:).4,000 

18,500 

5,490 

14,900 

6,520 

7,190 
16 FLOODS IN PENNSLYVANIA AND MARYLAND 

(7) Loyalhanna Creek at Kingston, Pa. 

Location.--Lat 40°17'35", long. 79°20 1 25", at Kingston, Westmoreland County, 60ft downstream 

from highway bridge, 150 ft upstream from Millers Run, 1.9 miles upstream from Ninemile Run, 

and 3 miles southeast of Latrobe. 

Drainage area.--168 sq mi. 

~--Recording gage. DatUm of gage is 1,014.16 ft above mean sea level, datum of 1929 (Corps 

---oY Engineers benchmark). 

Stage-discharge relation.--Defined by current-meter measurements below 8,200 cfs and extended to 

21,000 cfs by logarithmic plotting. 

Historical data.--Flood of March 17 or 18, 1936, reached stage of 14.5 ft; discharge 21,000 cfs. 

Remarks.--Regulation by Trout Run Reservoir (capacity, 48,130,000 cu ft) and diversion work at 

Kingston. Annual peak discharges not materially affected by regulation or diversion. 

Annual flood stages and discharges 

Gage Discharge Gage Discharge 

Date height (cfs) Date height (cfs) 

(feet) (feet) 

1936, Mar. 17 or 18- 14.5 ----------- 21,000 1945, Mar. 6··------- 10.00 ----------- 9,100 

1946, June 2-------- 9.46 ----------- 8,140 

1940, Mar. 30------- 9.83 ----------- 8,710 1947, June 8-------- 7.57 ----------- 4,760 

1941, June 5-------- 10.06 ----------- 9,300 1948, Apr. 14------- 9.22 ----------- 7,570 

1942, Apr. 9-------- 8.72 ----------- 6,640 1949, Jan. 26------- 7.74 ·----------- 4,900 

1942, Dec. 30------- 9.17 ----------- 7,570 1950, Jan. 7-------- 7.32 ----------- 4,270 

1944 Ma 7--------- 7.61 ----------- 4,760 

(8) Loyalhanna Creek at New Alexandria, Pa. 

Location.--Lat 40°23 1 40", long. 79°25'53", at highway bridge at New Alexandria, Westmoreland 

County, lt miles downstream from Crabtree Creek. 

Drainage area.--265 sq mi; 270 sq mi at site in use prior to August 1913. 

~--Nonrecording gage October 1910 to August 1918, August 1919 to July 1923, and November 1925 ~September 1940. Datum at New Alexandria site 917.26 ft above mean sea level (general adjustment of 1912). 

Stage-discharge relation.--Defined by current-meter measurements below 3,300 cfs and extended to 

31,000 cfs on basis of discharge measurements up to 14,000 cfs at Loyalhanna Creek Dam site 

and on basis of slope-area and contracted-opening measurements. 

Remarks.--Regulation by Trout Run Reservoir (capacity, 48,130,000 cu ft). Annual peak discharges 

not materially affected by regulation. 

Records August 1919 to July 1923, anQ November 1925 to September 1940 in reports of Pennsylvania Department of Forests and Waters. Records July 1910 to August 1913 in reports of Pennsylvania Department of Forests and Waters are incomplete. Unpublished records August 1913 to 

August 1918 considered unreliable. 

Annual flood stages and discharges 

Gage Discharge Gage Discharge 

Date height (cfs) Date height (cfs) 

(feet) (feet) 

1918, Feb. 9-------- 10.4 ---------- 6,800 1930, June 10------- 10.1----------- 6,500 

1931, Apr. 4-------- 10.3----------- 6,700 

1920, June 17------- 8. 70 ---------- 4,900 1932, Jan. 30------- 7.2----------- 3,400 

1921, Jan. 8-------- 7.2 ---------- 3,400 1933, Mar. 15------- 12.3----------- 9,200 

1921, Nov. 28------·- 10.60 ---------- 7,000 1934, Aug. 16------- 6.78---------- 3,100 

1923, May 13-------- 7.6 ---------- 3,800 1935, Aug. 3-------- 16.0----------- 16,000 

1936, Mar. 18------- 20.96---------- 31,000 

1926, Sept. 6------- 9.8 ---------- 6,100 1937' Apr. 26------- 15.09---------- 14,000 

1927, Jan. 21------- 8.95 ---------- 5,200 1937, Oct. 28------- 9.8----------- 6,100 

1927, Oct. 20------- 12.65 ---------- 9,700 1939, Feb. 3-------- 8.7----------- 4,900 

1929, Feb. 26------- 9.3 ---------- 5,500 1940, Mar. 31------- 12.9----------- 10,000 
FLOODS IN PENNSYLVANIA AND MARYLAND 

Youghiogheny River Basin 

(9) Youghiogheny River at Ohiopyle, Pa. 

17 

Location.--Lat 39°47 1 17", long. 79°29 1 4411 , at highway bridge in Ohiopyle, Fayette County, half a mile upstream f om Meadow Run. 

Draina~e area.--1, 62 sq mi; 1,029 sq mi at site of Weather Bureau gage at Confluence used prior 

to. 927. 

Gagp --Prior to. De ember 1927, Weather Bureau nonrecording gages at Confluence; thereafter, West nn Power Co. ecording gage at Ohiopyle. Datum of recording gage 1,198.91 ft above mean sea level. 

Stage-discharge re ation.--Defined by current-meter measurements below 16,000 cfs and extended to 

83,000 crs on b< sis of area-velocity studies. 

Historical data.-- lood of March 18, 1936, known to be highest and flood of March 29, 1924, second 

highest since 1 73. 

Remarks.--Regulatipn since July 1943 by Youghiogheny River Reservoir and since 1925 by Deep Creek 

Reservoir (comb ned capacity, 352,770 acre-ft). Annual peak discharges not materially affected 

by regulation. 

Records 1924 and 1928 to 1942 furnished by West Penn Power Co.; gage-height records 1873 

to 1923, and 19 5-27 from graphs based on nonrecording gage record at Confluence as published 

in reports of t e U. s. Weather Bureau. Ohiopyle record extended back to 1884 by this metbod. 

Date 

1874, Jan. 7------

1875, Aug. 2------

187:6, Sept. 18----

1877, Jan. 16-----

1877, Nov. 24-----

1879, Jan. 28-----

1880, Feb. 13-----

1881, Feb. 12-----

1882, Feb. 21-----

1883, Feb. 7------

1884, Feb. 5---·---

1885, Jan. 17-----

1886, Jan. 5------

1887, Feb. 4------

1888, Aug. 21-----

1889, May 31------

1890, Mar. 22-----

1891, Feb. 17-----

1892, Jan. 14-----

1893, Feb. 10-----

1894, Feb. 10-----

1895, Jan. 8------

1896, July 25·-----

1897, Feb. 22-----

1898, Mar. 25-----

1899, May 18------

1900, Feb. 8------

1901, Apr. 1------

1902, Feb. 28-----

1903, Feb. 4------

1904, Jan. 22-----

1905, Mar. 21-----

1906, Jan. 23-----

1907, Mar. 14-----

1908, Feb. 15-----

a Ohiopyle site 

Annual flood stages and discharges 

-

-

-

-

-

-

-

r--

r--

~-

~-

r--

~-

~-

Gage 

height 

(feet) 

10.9 

16.1 

14.0 

12.6 

13.7 

12.1 

13.0 

14.5 

12.3 

16.1 

15.5 

13.3 

11.0 

11.7 ~-· 19.5 ~- 16.1 ~- 14.0 

-- 14.9 

- 11.8 

-- 12.0 -- 10.1 

-- 13.4 

-- 14.5 -- 16.0 

-- 9.8 

-- 12.5 

-- 8.0 

-- ·12.1 

-- 13.3 -- ·11. 0 -- ·14 .3 

-- 10.3 

-- 10.8 -- 20.1 

-- 14.5 

Discharge 

(cfs) 

------------ 26,300 

------------ 49,700 

------------ 39,500 

------------ ·33, 900 

------------ 38,000 

------------ ·31, 200 

------------ 34,700 

------------ 42,000 

------------ 31,600 

------------ 49,700 

------------ 47,000 

------------ 36,100 

------------ 26,700 

------------ 29,500 

---------~-- 68,800 

------------ 49,700 

------------ 39,500 

-----------··· 44,000 

------------ 29,500 

------------ 30,400 

------------ 23,200 

------------ 36,600 

------------ 42,000 

------------ 49,700 

------------ 22,100 

------------ ·32, 500 

------------ 15,800 

------------ 31,200 

------------ 36,100 

------------ 26,700 

------------ 39,000 

------------ 22,100 

------------ 24,000 

------------ 70,600 

------------ 40,000 

and datum. 

Date 

£909, Feb. 

910, June 

1911, Jan. 

1912, Mar. 

1913, Jan. 

1913, Nov. 

1915, Jan. 

1916, Mar. 

1917, Jan. 

1918, Feb. 

1919, Jan. 

1920, June 

1921, Mar. 

1921, Nov. 

1923, Feb. 

1924, Mar. 

1925, Feb. 

1926, Feb. 

1927, Jan. 

Change in 

1928, May 

1929, Feb. 

1929, Oct. 

1931, Apr. 

1932, Apr. 

1933, Mar. 

1935, Jan. 

1936, Mar. 

1937, Apr. 

1937, Oct. 

1939, Feb. 

1940, Mar. 

1941, June 

1942_, Apr. 

24------

19------

30------

21------

8-------

16------

7-------

22------

22------

20------

1-------

17------

3-------

28------

13------

29------

12------

22------

21------

Gage 

height 

(feet) 

8.7 

13.1 

13.2 

18.1 

11.5 

10.7 

11.2 

13.5 

14.6 

12.'5 

11.3 

12.1 

10.1 

11.5 

10.1 

a13.0· 

9.4 

9.7 

10.7 

site and datum 

1-------- 9.23 

27------ 6.2£ 

3------- 7.33 

4------- 6.27 

1------- 7.11 

14------ 8.94 

22------· 7.18 

18------ 13.3C 

26------ 10.74 

28------ 8.86 

3------- 8.15 

31------ 7.79 

5------- 9.34 

10---.--- 6.69 

Discharge 

(cfs) 

----------- 16,400 

----------- 33,400 

----------- 33,800 ------~-----59,000 

·----------- 26,700 

----------- 23,600 

----------- 25,500 

----------- 35,200 

----------- 40,500 

----------- 30,800 

----------- 25,900 

----------- ·29,100 

----------- 21,400 

----------- 26,700 

----------- 21,400 

----------- 81,000 

----------- 18,800 

----------- 19,900 

----------- 23,600 

----------- 32,300 

----------- 18,100 

----------- 24,000 

----------- 16,700 

----------- 22,200 

----------- 36,800 

----------- 22,900 

----------- 82,100 

----------- 54,200 

----------- 36,300 

----------- 30,100 

----------- 27,400 

----------- 40,400 

----------- 19,400 
18 FLOODS IN PENNSYLVANIA AND MARYLAND 

(10) Youghiogheny River at Connellsville, Pa. 

Location.--Lat 40°01'05", long. 79°35 1 40", at Crawford Avenue Bridge in Connellsville, Fayette 

County, three-quarters of a mile upstream from Mounts Creek. 

Drainage area.--1,326 sq mi. 

~--Nonrecording gage prior to August 1928 and recording gage thereafter. Datum of gage is -~0.13 ft above mean sea level (Baltimore & Ohio Railroad benchmark). 

Stage-discharge relation.--Defined by current-meter measurements below 55,000 cfs and extended 

to 93,000 cfs. 

Historical data. --Flood of April 12•, 1860, reached stage of 16.5 ft ·(prior to destruction of 

slackwater dams). 

Remarks.--Regulation since July 1943 by Youghiogheny River Reservoir and since 1925 by Deep Creek 

Reservoir (combined capacity, 352,770 acre-ft). Annual peak discharges not materially affected 

by regulation. 

Records from July 1908 to September 1941 in reports of Pennsylvania Department of Forests 

and Waters. Annual floods prior to 1909 from Water Supply Commission of Pennsylvania Report, 

Part 8, Floods. (Record for 1891 computed from Weather Bureau gage readings at West Newton. 

Records for 1896-1908 computed from Trotter Water Co., gage readings}. 

Annual flood stages and discharges 

Discharge Discharge 

Date (cfs) Date (cfs) 

1888) Aug. 21-22---- 17.8 ---------- 70,000 19~8, Feb. 20------- 14.0 ----------·42,000 

1919, Jan. 1-------- 11.51 ---------- 27,900 

1891, Feb. 17------- 14.7 ---------- 46,600 1920, Mar. 13------- 12.13 ---------- 30,900 

1921, Mar. 3-------- 10.10 ---------- 21,500 

1896, July 25------- 15.0 ---------- 48,600 1921, Dec. 24-'------ 11.60 ---------- 28,400 1~97, Feb. 23------- 16.7 ---------- 61,200 1923, Feb. 2-------- 8.9 ---------- 16,700 

1898, Aug. 11------- 11.2 ---------- 26,400 1924, Mar. 29------- 19.4 ---------- 84,000 

1899, May 18-------- 13.0 ____ ....; _____ 35,800 1925, May 10-------- 9. 70 ·---------- 19,900 

1900,----(less than) 8.9 ---------- 16,700 1926, Feb. 23------- 10.4 ---------- 22,800 

1927, Jan.'22------- 11.8 ---------- 29,400 

1902, Feb. 28------- 15.8 ---------- 54,400 1928, May 1--------- 13.7 ---------- 40,000 

1903, Feb. 28------- 12.7 ---------- 34,200 1929, Feb. 27------- 9.48 ---------- 19,100 

1904, Mar. 1-------- 13.7 ---------- 4Q,OOO 1929., Oct. 3-------- 12.00 ---------- 30,400 

1905, Mar. 21------- 12.0 ---------- 30,400 1931, Apr. 4-------- 9.95 ---------- 21,100 

1932, Apr. 1-------- 11.00 ---------- 25,500 

1907, Mar. 14------- 18.4" ---------- 75,200 1933, Mar. 14------- 14.9 -----------48,000 

1908, Feb. 15------- 14.4 ---------- 44,600 1934, .Mar.4--------- 10.77 ---------- 24,600 

1909, Feb. 24---·---- 9.36 ---------- ·18, 700 1935, Jan. 22------- 10.83 ---------- 24,600 

1910, June 19------- 13.09 ---------- 36,400 1936, Mar. 18------- 20.28 ---------- 92,500 

1911, Jan. 30------- 12.98 ---------- 35,800 1937, .Apr. 26------- 15.87 ---------- 55,100 

1912, Mar. 21------- 17.28 ---------- 66,000 1937, Oct. 28------- 14.35 ---------- 44,600 

1913, Jan. 8-------- 13.50 ---------- 38,800 1939, Feb. 3-------- 13.37 ---------- 38,200 

1913, Nov. 16------- 11.50 ---------- 27,900 1940, Mar. 31------'-- 13.16 ---------- 37,000 

1915, J:an. 7-------- 12.13 ---------- 30,900 1941, June 5-------- 17.02 ---------- 63,600 

1916, Mar. 22------- 15.00 ---------- 48,600 1942, Mar. 9-------- 10.62 ---------- 23,700 

1917 Jan. 22-------· 15.20 ---------- 50,000 
YOUGHIOGHENY RIVER BASIN 19 

(11) Youghiogheny River at Sutersville, Pa. 

Location.--Lat 40°14 1 25", long. 79"48 1 25 11 , at Sutersville, Westmoreland County, 500ft upstream 

from highway bridge and 2.1 miles downstream from Sewickley Creek. 

Drainage area.--1,715 sq mi. 

Gage.--Nonrecording gage ~une 1915 to September 1936 and December 1938 to June 1939; recording 

gage thereafter. Datum .of gage is 733.36 ft above mean sea level, datum of 1929, ParkersburgUniontown supplementary adjustment of 1944. 

Stage-discharge relation.--Defined by current-meter measurements below 77,000 cfs and extended 

to 100,000 cfs on basis of slope-area method. 

Remarks.--Regulation since July 1943 by Youghiogheny River Reservoir and since 1925 by Deep Creek 

Reservoir (combined capacity, 352,770 acre-ft). Annual. peak discharges not materially affected 

by regulation. 

Records from June 1915 to September 1929, June 1931 to September 1936, and December 1938 

to September 1941 in reports of Pennsylvania Department of Forests and Waters. Records from 

November 1890 to June 1915 and October 1929 to June 1931 computed on basis of comparison with 

Weather Bureau records for West Newton about 2 miles upstream. 

Annual flood stages and discharges 

Discharge Discharge 

'Date (cfs) Date (cfs) 

1891, Feb. 17------- 21.1 ---------- 52,200 1918, Feb. 20------- 18.73 ---------- 42,600 

1892, Jan. 14------- 15 .. 9 ---------- 32,800 1919, Jan. 2-------- 16.2 ---------- 33,800 

1893, Feb. 11------- 13.8 ---------- 26,000 1919, Nov. 27------- 17.0 ---------- 36,500 

1894, Feb. 10------- 11.7 ---------- 19,700 1921, Mar. 3-------- 12.8 ---------- 23,000 

1895, Jan. 8-------- 16.~ ---------- 36,200 1921, Nov. 29------- 19.1 ---------- ·44, 200 

1896, July 25------- 20.0 ----------· _4 7,800 1923, Feb. 14------- 11.4 ---------- 18,900 

1897, Feb. 23------- 24.2 ---------- 64,800 1924, Mar. 30------- 27.5 ---------- 78,900. 

1898, Mar. 22------- 13.8 ---------- 26,00() 1925, Feb. 8-------- 12.26 ---------- 21,500 

1899, May 18-------- 16.9 ---------- 36,200 1926, Feb. 23------- 12.5 ---------- 22,100 

1900, Feb. 9-----.--- 11.3 ---------- 18,600 1927, Jan. 22------- 14.50 ---------- 28,200 

1901, Apr. 7-------- 16.6 ---------- 35,100 1927, Oct. 20------- 18.50 ---------- 41,9.00 

1902, Mar. 1-------- 23.2 ---------- 60,600 1929, Feb. 27------- 12.17 ---------- 21,200 

1903, Mar. 1-------- 17.3 ---------- 37,600 1929, Oct. 3-------- 16.9 ---------- 36,200 

1904, ~an. 22----------------------- 44,000 1931, Apr. 5-------- 12.7 ---------- 22,700 

1905, Mar. 21------- 16.0 ---------- 33,100 1932, Apr. 1-------- 15.3 ---------- 30,800 

1906, Jan. 23------- 15.9 ---------- 32,800 1933, Mar. 14------- 21.06 ---------- 52,200 

1907, Mar. 14------- 30.E ---------- 100,000 1934, Mar. 4-------- 23.0 ---------- 31,000 

1908, Feb. 15------- 20.8 ---------- 51,000 1935, Jan. 22------- 15.3 ---------- 30,800 

1909, Feb. 24------- 13.1 ---------- 23,900 1936, Mar. 18------- 30.65 ---------- 100,000 

1910, Jan. 19------- 17.4 ---------- 37,900 1937, Apr. 26------- 22.8 ---------- ·59 ,000 

1911, Jan. 30------- 18.0 ---------- 40,000 1937, Oct. 29------- 20.3 ---------- 49,000 

1912, Mar. 21------------· ---------- 69,100 1939, Feb. 4-------- 18.5 ---------- 41,900 

1913, Jan. 8-------- 18.7 ---------- 42,600 1940, Mar. 31------- 18.40 ---------- 41,500 

1914, Mar. 16------- 17.8 --------~- 39,300 1941, June 5-------- 27.34 ---------- 78,000 

1915, Feb. 2-------- 17.9 ---------- 39,600 1942, Apr. 10------- 14.46 ---------- 28,200 

1916, Mar. 23------- 20.5 ---------- 49,800 

1917 Jan. 22------- 20.5 ---------- 49,800 
20 FLOODS IN PENNSYLVANIA AND MARYLAND 

(12) Casselman River at Markleton, Pa. 

Location.--Lat 39°51 1 3511 , long. 79°13 1 4011 , at highway bridge at Markleton, Somerset County, 2 miles 

southwest of Casselman and 7 miles downstream from Coxes Creek. 

Drainage area.--382 sq mi. 

Gage.--Nonrecording gage August 1913 to November 1940 and recording gage thereafter. Datum of 

---gage is 1,655.29 ft above mean sea level, adjustment of 1907. 

Stag~-discharge relation.--Defined by current-meter measurements below 13,000 cfs and extended to 

36,000 cfs by slope-area .method. 

Remarks.--Slight diversions above station to borough of Salisbury, Pa., and to city of Frostburg, 

Md., do not materially aff~ annual peak discharges. Records August 1913 to September 1941 in 

reports of Pennsylvania Department of Forests and Waters. Records for station at Confluence 

not used because of severe backwater effect at flood stages. Fragmentary records prior to 1915. 

Annual flood stages and discharges 

Gage Discharge Gage Discharge Date height (cfs) Date height (cfs) 

(feet) (feet) 

1915, Jan. 7-------- 8.5 ----------- 11' 900 1933, Mar. 14------- 9.8 ----------- 15,700 

1916, Mar. 22------- 8.9 ----------- 13,100 1934, Aug. 16-------· 8.7 ----------- 12,500 

1917, Jan. 22------- 10.0 ----------- 16,200 1935, Jan. 22------- 7.6 ----------- 9,350 

1918, Feb. 26------- 9.7 ----------- 15,400 1936, Mar. 17------- 16.4 ----------- 35,800 

1919, Jan. 2-------- 7.5 ----------- 9,070 1937, Apr. 26------- 12 .8· ----------- 24,600 

1920, Mar. 12------- 8.4 ----------- 11,600 1937' Oct. 28------- 10.0 ----------- 16,200 

1921, Mar. 3-------- 7.5 ·----------- 9,070 1939, Feb. 3-------- 8.7 ----------- 12,500 

1921, Nov. 28------- 7.55 ----------- 9,350 1940, Mar. 31------- 7.8 ----------- 9,910 

1923, Feb. 2-------- 6.6 ----------- 6,650 1941, Jtine 5-------- 10.24 ----------- 18,700 

1924, Mar. 29------- 12.17 -----------· 22,800 1942, Mar. 9-------- 7.35 ----------- 9,330 

1925, Feb. 12------- 6.5 ----------- 6,400 1942, Dec. 30------- 8.42 ----------- 12,500 

1926, Jan. 19------- 7.5 ----------- 9,070 1944, May 7--------- 6.77 ----------- 7,620 

1927, Jan. 5-------- 7.4 ----------- 8,790 1945, Feb. 27------- 8.63 ----------- 13,200 

1928, Apr. 30------- 10.00 ----------- 1"6, 200 1946, June 2-------- 7.24 ----------- 8,740 

1929, Feb. 26------- 7.0 ----------- 7,700 1947, July 31------- ·6.98 ----------- 8,170 

1929, Oct. 3-------- 7.6 ----------- 9,350 1948, Apr. 13------- 8.16 ----------- 11,800 

1931, Apr. 4-------- 7.4. ----------- 8,790 1949, Jan. 26------- 7.23 ----------- 8,740 

1932, Apr. 1-------- 7.2 ----------- 8,240 1950, Mar. 28-----'-- 7.55 ----------- 9,940 

(13) Big Piney Run near Salisbury, Pa. 

Location.--Lat 39°43'32", long. 79°02'57", an eighth of a mile upstream from Little Piney Run, a quarter of a mile north of Maryland-Pennsylvania State line, and 2! miles southeast of Salisbury, Somerset County. 

Drainage area.--24.5 sq mi. 

Gage.--Recording gage. 

Stage-discharge relation.--Defined by current-meter measurements below 500 cfs and extended to 

4,300 cfs on basis of slope-area determination at 4,100 cfs. 

Annual flood stages and discharges 

Gage Discharge Gage Discharge 

Date height {cfs) Date height (cfs) 

(feet) (feet) 

1933, Mar. 14-----.. -- 6.1 ------------ 1,900 1942, May 16--------- 4.67 ------------ 1,290 

1934, Jan. 7--------- 5.1 ------------ 968 1943, Oct. 15-------- 6.21 ------------ 3,460 

1935, Feb. 15-------- 4.05 ------------ 494 1944, May 7---------- 3.88 ------------· 628 

1936, Mar. 17 --------· 7.5 ------------ 4,100 1945, Feb. 27-------- 4.42 ------------ 1,050 

1937, Apr. 26-------- 7.6 ·------------ 4,300 1946, June 19-------- 4.26 ------------ 908 

1937, Oct. 28-------- 6.04 ------------ 1,860 1947, Mar. 14-------- 3.89 ------------ 634 

1939, Jan. 31--------· 5.28 ------------ 1,180 1948, Jan. 1---------· 4.2~ ------------ 876 

1940, Aug. 27-------- 5.69 ------------ 1,510 1949, Jan. 26-------- 3.62 ------------ 472 

1941, June 4--------- 5.38 ------------ 1,260 1950, Mar. 27-------- 4.12 ------------ 796 
YOUGHIOGHENY RIVER BASIN 21 

(14) Laurel Hill Creek at Ursina, Pa. 

Location.--Lat 39°49 115", long. 79°19 1 15 11 , at Ursina, Somerset County, 500 .ft downstream .from 

bridge on State Highway 53 and 2.7 miles upstream .from mouth. 

Drainage area.--121 sq mi. 

Gage. -·-Nonrecording gage .from August 1913 to July 1939 and recording gage therea.fter. Datum o.f 

recording gage 1,335.26 .ft above mean sea level, unadjusted. Datum o.f nonrecording gage, at 

site 0.7_miles downstream, 1,329.06 .ft above mean sea level. 

Stage-discharge relation.--Prior to July 1939, de.fined by current-meter measurements below 4,600 

c.fs, and extended to 11,000 c.fs on basis o.f slope-area determination; therea.fter, de.fined by 

current-meter measurements below 5,400 c.fs and extended to 9,400 c.fs. 

Remarks.--Slight regulation at low .flow by mills upstream. Records .from August 1913 to September 

1941 in re~orts o.f Pennsylvania Department o.f Forests and Waters. Records .for station at 

Con.fluence not uSed because o.f severe backwater e.f.fect at .flood stages. 

Annual .flood stages and discharges 

Gage Discharge Gage Discharge 

Date height ( c.fs) Date heigh) (c.fs) 

(.feet) (.feet 

1914, June 28------- 6.20 ------------ 3,220 1933, Mar. 14------ 7.5 ----------- 4,860 

1915, Jan. 7-------- 6.99 ------------ 4,140 1934, Aug. 16------ 6.6 ----------- ·3, 660 

1916,. Mar. 22.------- 8.0· ------------ 5,630 1935, Aug. 2------- 6.86· ----------- . 4,020 

1917, Jan. 22-----.;..- 8.2 ------------· 5,970 1936, Mar. 17------ -10.28 ----------- 10,300 

1918, Feb. 20------- 8.0 ------------ 5,630 1937, Apr. 26------ 7.5 ·----------- 4,860 

1919, Jan. 2-------- 6 .. 1 ------------ 3,110 1937, Oct. 28------ 7.6 ----------- 5,010 

1920, June 17------- 7.2 ------------ 4,410 1_939, Feb. 3------- 7.58 ·----------~- 5,010 

1921, Jan. 23------- 6.1 ------------ 3,110 Change in site and datum 

1921, Dec. 24------- 6.31 ------------ 3,330 1940, Mar. 30------ 6.28 ·----------- ·6,510 

1923, July 11------- 5.1 ------------ 2,070 1941, June 4------- 7.98 ----------- 9,400 

1924, Mar. 29------- 9.30 ------------ 8,090 1942, Apr. 9------- 4.57 ----------- 3,580 

1925, Feb. 9-------- 7.9 ------------- 4,300 1942, Dec. 30------ 5.81 ----------- ·5,660 

1925, Oct. 25------- 6.66 ------------ 3,780 1944, Apr. 23------ 4.24 ----------- 3,100 

1927, Jan. 21------- -8.0- ------------ 5,630 1945, Mar. 6------- 5.96· ----------- 6,000 

1927, Oct. 19------- 8.20 ------------ 5;970 1946, June 2------- 5.12 ----------- 4,470 

1929, June 28------- 5.15 ------------ 2,170 1947, July 31------ 5.91 ----------- ·5 ,830 

19Z9, Oct. 3--------· 7.10 ------------ 4,2'70 1948, Apr. 13------ . 5.4a ----------- 5,150 

1931, Apr. 4-------- 5.76 ------------ 2,780 1949, Aug. 18------ 5.20 ----------- 4,360 

1932, Mar. 31---·----· 5.45 ------------ 2,370 1950, Apr. 24------ 4.31 ----------- 2,900 
22 FLOODS IN PENNSLYVANIA AND MARYLAND 

(15) Green Lick Run at Green Lick Reservoir, Pa. 

Location.--Lat 40°06'20", long. 79°30 1 05 11 , at upstream errd of Green Lick Reservoir, Fayette 

County, 1.3 miles upstream from Latter Run, and 3! miles southeast of Mount Pleasant. 

Drainage area.--3.07 sq mi. 

Gage.--Recording gage. 

Stage-discharge relation.--Defined by current-meter measurements below 150 cfs and extended to 

550 cfs by logarithmic plotting. Discharges for flood crests affected by backwater determined 

by slope-area·method. 

Remarks.--Records prior to August 1941 furnished by Municipal Authority of Westmoreland County. Records prior to 1929 incomplete; gage placed in operation-about 1915. 

Date 

1929, Feb. 26------- 2.21 

1929, Oct. 2 .... ------- 2.69 

1931·, May 7--------- 2.77 

1932, Mar. 31------- 2.32 

1933, Mar. 13------- 2.67 

1934, Mar. 3-------- 2.44 

1935, Aug. 2-------- 2.85 

1936, Mar. 17------- 3.18 

1937, Apr. 25------- 2.46 

1938, July 18------- 3.21 

1939, Feb. 3-------- 2.40 

Annual flood stages and discharges 

Discharge 

(cfs) 

------------- 126 

------------- 266 

------------- 298 

------------- 153 

------------- 260 

------------- 186. 

------------- 332 

------------- 508 

------------- 191 

------------- 526 

------------- 174 

Date 

1940, Mar. 

1941, June 

1942, Mar. 

1943, Aug. 

1944, May 

1945, Mar. 

1946, July 

1947, June 

1948, Apr. 

1949, Aug. 

1950, Jan. 

30------- 2.73 

4-------- 3.20 

9-------- 2.72 

13------- 5.1 

24-------- 5.42 

6-------- 2.54 

1-------- 3.24 

7-------- 2.70 

12------- 2.40 

18------- 2.66 

6-------- 2.43 

Discharge 

(cfs) 

----------- 282 

----------- 520 

------·---- 278 

----------- 1,400 

----------- 590 

----------- 216 

----------- 546 

----------- 270 

----------- 174 

----------- 256 

----------- 183 

INT--PUP. SEC., WASH. • D.C. 27096