840 
BULLETIN OF THE BUREAU OF FISHERIES 
Two-thirds of the total run-off for the year thus falls during the three spring 
months, and more than half of it during April and May. This does not exactly 
represent the natural condition, because the Kennebec is more or less controlled by 
the several dams; but water-power developments have not been sufficient to mask 
its spring freshets — still less have they on the Penobscot or the St. John Rivers. 
Hence, the seasonal fluctuations in the flow of the Kennebec may be taken as gen- 
erally representative of all the considerable streams that empty into the gulf north 
and east of Cape Elizabeth and of the Saco as well. 
Originally the Merrimac, also, came into flood in the spring, at the season when 
the snow blanket melts and the ice goes out; but it is now so largely harnessed for 
industrial purposes that its seasonal flow no longer shows as pronounced a freshet 
in April and May as New England waterways do in their natural state. Its largest 
run-off still falls in April, however, and its smallest in September, as appears from 
the following table: 
Merrimac River at Lawrence, Mass., for the period 1907 to 1916 
Month 
Run-off, 
in inches 
Month 
Run-off, 
in inches 
January 
1.3 
August 
0.8 
February 
1. 2 
.6 
March 
2.7 
.8 
April 
3. 6 
1.0 
May 
2.3 
1. 3 
1.1 
.8 
1.4 
Automatic tide gauges, which have been in operation at a number of points 
around the coastline of the gulf between Cape Cod and the Bay of Fundy, have 
shown the sea 0.1 to 0.2 feet lower than the mean in the latter part of winter, and 
about this same amount higher than the mean toward the end of the summer. 36 
This variation probably reflects the seasonal variation in the inflow of land water. 
RAINFALL AND EVAPORATION 
Although land drainage is the chief source for fresh water for the gulf, rainfall 
also adds a considerable increment. No record of the precipitation over the offshore 
parts of the gulf itself is available, but the monthly and annual averages for four 
representative coast stations — Boston, Portland, Eastport, and Yarmouth — tabu- 
lated below suggest an annual fall of 40 to 45 inches for the gulf as a whole. 
Average rainfall, in inches 
Month 
Boston 
Port- 
land 
East- 
port 
Yar- 
mouth 
Month 
Boston 
Port- 
land 
East- 
port 
Yar- 
mouth 
January 
3. 82 
3. 44 
4. 08 
3. 60 
3.55 
3.03 
3. 36 
3.81 
3. 65 
3. 75 
3.11 
3.67 
3. 36 
3. 25 
3.84 
3. 62 
4. 28 
2.94 
3. 80 
3. 24 
3.42 
5. 16 
4.17 
5.00 
3. 82 
3. 57 
2.93 
3. 47 
August .. . _ 
4.03 
3. 19 
3. 86 
4. 10 
3.41 
3. 57 
3. 20 
3. 66 
3. 80 
3.68 
3. 26 
2. 97 
3. 85 
4. 08 
3. 97 
3. 62 
3.61 
4. 12 
4.49 
4. 77 
February 
September 
March 
October 
April. .... 
November 
May 
June 
July 
December 
Total 
43.40 
42.50 
43. 30 
48.73 
“Information contributed by U. S. Coast and Geodetic Survey t 
