18C150 Morse Creek below Aqueduct
Technical Notes: 2005 Water Year
Christopher Evans

Introduction
Ecology’s telemetry stream gage on upper Morse Creek is located at the site of old USGS 
gage 12047300, just below the City of Port Angeles’ aqueduct at river mile 6.4.  This 
gage was operated from October 1, 2004 to September 30, 2005.  Stage reference 
observations were taken from the staff gage located at the station approximately one time 
each week for the period of record.  The cross-section filled slightly during the water 
year.  The annual mean discharge for the water year was 71 cfs compared to an annual 
mean discharge of 108 cfs for water year 2004.  Discharge ranged from a low of 15 cfs to 
a high of 847 cfs for the water year. 

Stage Record
The stage record for the water year is complete with the exception of a 15 day gap in 
December created by a broken power cable.  The gap in the data was filled with data 
from Ecology station 18N050 Little River nr Mouth.  The relationship between the two 
data sets has a correlation coefficient of r = 0.97.  To correct for instrument drift, the 
difference between the logged stage and the observed stage, the record has been adjusted 
to the known individual stage reference observations.  The recorded range of stage for the 
period of record was 3.23 ft.  A low of 1.02 ft was recorded on September 02, 2005, and a 
high of 4.25 ft was recorded on December 10, 2004.  Periodic spikes and jumps in the 
data are related to the operation of the City of Port Angles’ Hydro Project located just 
upstream.  The spikes are equivalent to 15 cfs and can also be seen in the hydrograph at 
the lower Ecology station 18C070.

Rating Curve
Two rating curves were used during water year 2005.  These curves included three new 
discharge measurements.  A high water event in December 2004 slightly filled the cross-
section with sediment.  The lowest discharge measurement taken during the water year 
was 20 cfs.  Discharge was below 20 cfs for 4% of the period of record.  To determine 
the lowest recorded discharge for the year, a regression of the velocity and area of the 
three lowest measurements was used to calculate a discharge of 15 cfs at a stage of 1.02 
ft.  The highest measured discharge for water year was 56 cfs.  However, the highest 
rating point used in the curve is at 781 cfs measured in 2003.  Flows exceeded 781 cfs 
less than 1% of the water year.