18A050 Dungeness River near Mouth
Technical Notes: 2005 Water Year 
Christopher Evans

Introduction

Ecology’s telemetry stream gage on the Dungeness River is located at river mile 0.08 
near the old school house bridge.  This gage was operated from October 1, 2004 to 
September 30, 2005.  Stage reference measurements were taken from the station staff 
gage approximately one time each week for the duration of the water year.  Annual mean 
discharge for water year 2005 was 260 cfs.  In comparison, the mean annual discharge 
from water year 2001 to water year 2004 (Ecology’s period of record) is 332 cfs.  The 
instantaneous low discharge for the year was 56 cfs.  The instantaneous high discharge 
for the year was 3270 cfs.  

Stage Record

The stage record for the water year is complete with no gaps.  To correct for instrument 
drift the record has been adjusted to known individual staff gage readings.  The recorded 
range of stage for the water year was 7.17 ft.  A low of 0.71 ft. was recorded on October 
5, 2004, and a high of 7.88 ft. was recorded on December 11, 2004.  Because of a shift in 
the channel the instantaneous low stage value in October 2004 is not equal to the lowest 
discharge.  The lowest discharge of the water year occurred in September 2005.  

Rating Curve

Two rating curves were used during the water year encompassing six discharge 
measurements.  The high water event on January 11, 2005, filled the cross-section 
approximately 0.20 ft.  Subsequently the second rating was adjusted for this substrate 
shift and filled with new points over the summer.  The new discharge measurements 
ranged from a low of 61 cfs to high of 1691 cfs.  Discharge was below the lowest 
measured discharge 1% of the water year.  This is equivalent to a stage range of 0.04 ft 
down to the lowest recorded discharge.  

Flows were above the highest measured discharge 1% of the water year.  Manning’s N 
equation was used to calculate the high end of the curve.