PERMFILE108821

• Permit No: M1980047
• IBM Index Class Name: Permit File
• Section_Exhibit Name: EXHIBIT G WATER INFORMATION
• Media Type: D
• Archive: No

STREAM FLOW
Surface and subsurface contributions to the stream channels of
the Davis and Middle Fork creeks are a fundamental component of
the hydrologic regime of the watersheds. The quantity of water
that appears annually as runoff in the streams is dependent on
a number of factors, including (1) the amount of precipitation
received in the forms of rainfall and snow; (2) watershed topog-
raphy, soils, and geology; and (3) influencing climatic elements.
A number of stream gaging stations have been operated in past
years within the Parachute Creek basin by both USGS and Colony
Development Operation (See Figure G-2). The flow records from
these stations provide much of the information needed to define
the runoff characteristics. Eleven stations have been oper-
ated on the Dow West Property by Colony; three have been operated
by USGS at locations on Parachute Creek below the Dow Property.
• The descriptions of the stations and the recorded runoff volumes
are presented in this section. Descriptive data for each of the
stations on site are summarized in Table G-2. Gaging stations
have also been operated in the basin by the Standard Oil Company
of California and the Union Oil Company of California. This
data has not been included in Colony's analysis as it has not
been released by the specific companies.
Results from the analysis of surface runoff characteristics for
the project site area can be summarized as follows: the flow
in Parachute Creek averages 30.3 cubic feet per second (cfs) just
below the town of Grand Valley (12 year average; 1921-1927, 1948-
1954). The recorded extremes at the Grand Valley gauging station
are a maximum flow of 912 cfs in May of 1952 and a reading of
0 cfs for certain periods in 1926-27 and 1949. The tributaries
to the main stem of Parachute Creek also show wide fluctuations
in extreme flows. Based on flow data from above and below the
mouth of Parachute Creek (Table G-3), it can be seen that Parachute:

G-4