Polk County observer. (Monmouth, Polk County, Or.) 1888-1927, 1910-06-21
BountifuI Water supply.

The dominant physical feature of
the valley is it's stream system. The
willamette river rises in the south
eastern corner of the water shed in
the junction of the Calapooias with
the high Cascades. Following north
erly it follows the trough of the val
ley and empties into the Columbia at
the northern extremity of the valley.
From the Cascade Range on the east,
network of tributaries make their
way toward the trunk stream. Among
these are several of the larger streams
of the State, such as the Middle Fork,
the Mckenzie, the Santiam, the Mol
ALA and the Clackamas. There are
a, number of tributaries from the Coast
Range on the west, but the flow of
these is neither so large nor so con-
slant as that which comes from the
high watershed of the Cascades.
Among the principal streams enter
ing the valley from the west are the
Coast Fork, the Tualatin, the YAM
hill, the Luckiamute and Mary's rivers.
mately as per cent of the rainfall of
the year occurs, leaving but 20 per
cent or about 10 inches of rain for
the six months of the dry season, from
April to September, when many crops
are making their greatest demand ior
moisture. During Aprl, May and the
early part of June the rainfall in aver
age years is abundant for all crops,
and in some years more than abund-
ant; but from June Is of each year to
September Is the rainfall averages
but 2.5 inches per month, which is en-
tirely insufficient to maintain proper
m moisture conditions in the average
soils of the valley.
Rainfall Not Well Distributed.
The character of the rainfall during
the summer period must also be taken
into account in considering the mat
ter. The records show that the major
ity of the rains occurring in this per-
iod are little more than showers, and
although their aggregate makes
considerable showing, they are of little
value to growing crops.
The season of 1907 illustrates this
point clearly. The total amount of
rainfall and its distribution were
about normal The summer rainfall
came in three distinct shower periods
the first occurring in the latter part
Of June and the first part of July, the
second occurring about the middle Of
August and the third toward the end
OF August.
The late spring rainfall ceased on
June Is. Between that time and the
first shower period on June 2s, there
were few showers at different points
in the valley, but no general rain. The
heaviest shower at any point during
this period was 0.O9 inches at Port
land on June 21. During the first per-
iod the heaviest rain occurred at Port
land on July 2. when l inch of rain
fell. The only other rainfall Of value
was at Albany on July 3. when O.45
inch fell. Between the first and second
shower periods. there was no rainfall
anywhere in the valley except on July
IA and rs at Eugene. when 0.04 inch
and COS inch occurred. respectively.
These were so small, however. as to be
negligible. For a period Of thirty-three
days, therefore. the valley was without
appreciable rainfall. 1t will be seen
that in the months which make the
greatest demand for moisture, the
rainfall Is so light as 10 make condi-
tons almost comparable with those
existing during the same period in the
truly arid eastern parts Of oregon and
Washington. or elsewhere.
Valley Compared 20 Italy.
As showing what is already being
accomplished with irrigation under
climatic conditions similar to those
existing IN the willamette valley.
brief reference viii be made 70 the
Po valley in northern Italy. where.
Notwithstanding the existence of hu-
mid climate. irrigation has been de-
PENDED upon for centurss 20 bring
about the fullest agricultural produc-
tiou. The upper part of the valley of the
Po resembles in many respects the
wIIlamette Valley. On three sides u h
surrounded by high mountains-the
AIrs On the north and east and the
apenuincs on the south-from which n
network of streams make their way %
the Pc. the trunk stream of TIE valley
TIse valley consists q . foothin sec
ton and of broad isrei plaina Situated