13 
An index and period of record listing for CMD stations in Ontario 
were made available to the project subsequent to the nublication date. 
The index has been anpended to this report as Appendix II; however, 
since the data had already been summarized for this report, Tables 1-5 
and Figures 2-9 have not been changed to fit the new informaticn in 
Anpendix II. Footnotes have been added at anplicable points to Tables 
1 and 2 to call attention to this fact. 
Information of the lengths of records of U. S. Coast Guard instal- 
lations is not readily available, but may be obtained for four- 
hourly stations from the Coast Guard Headquarters at Washington, D. C., 
and for six-hourly stations from the National Weather Records Center at 
Asheville. 
Water level records obtained from gaugings of the U. S. Lake Survey 
and Canadian Hydrographic Service are available back to 1860 for each 
Lake and for connecting waterways. The single exception is the St. Clair 
River, for which records are available back to 1898. 
The water level records are regularly published as monthly means, 
in both tabular and hydrograph form, for each Lake taken as a unit. 
Records for individual gauges are available only upon specific request. 
Periods of record vary among individual gauges, and hence the date 1860 
does not necessarily refer to any particular gauge, but rather to aver- 
age values for each Lake. 
C United States water level data are available from the U. S. Lake 
Survey, U. S. Army Corps of Engineers, 630 Federal Building, Detroit 26, 
Michigan. 
Canadian water level data are available from the Dominion Hydrog- 
rapher, Canadian Hydrographic Service, Canada Department of Mines and 
Technical Surveys, Ottawa, Ontario. 
, The periods of record for some sources may vary internally, that 
is, different observations have been carried out for varying lengths of 
time. In such cases the notation "variable--see data'' has been entered 
in the Period of Record column, and the appropriate dates have been 
entered in the individual parameter columns. In some of these cases, 
the period of record is known for some data, but not for others. In 
this event, observations known to be taken, but for which the period of 
record is unknown, are indicated by "(X)". 
The symbol "X'" (not enclosed by parentheses) is used in two in- 
stances, 1) whenever it is known that the period of record is homogen- 
eous for the observations taken; that is, whenever there is a single 
known period of record which embraces all the observations made at the 
particular station, and 2) whenever it is known that observations are 
made at the station, but the period of record is not known for any of 
them. 
Unmarked spaces in Table 1 indicate that, so far as it is known to 
the investigators, no observations are made of that parameter. 
