18A050 Dungeness River nr Mouth
Technical Notes: 2006 Water Year
Christopher Evans

Introduction

Ecology’s telemetry stream gage on the Dungeness River is located at the Sequim-
Dungeness Way Bridge.  This report encompasses the water year 2006.

Stage Record

During water year 2006, data was recorded every 15 minutes from October 1, 2005 
through September 30, 2006.  The recorded range of stage for the period of record was 
6.82 ft. 

The daily mean discharge table reports reliable discharge values between two times the 
highest measured discharge and one-half the lowest measured discharge.  Data outside of 
this range are considered an unreliable estimate and are not reported.  Logged data that 
drifted more than 20% from direct observed gage heights is coded as an estimate (50).

With the exception of a December 25th high water event, all stage data was within the 
reliable range of the rating during the water year 2006 period of record.

Annual Mean:   	415 cubic feet per second (cfs)                                                                                                                                                 
Annual Median:  	260 cfs
Max. Daily Mean:	2480cfs  
Min. Daily Mean: 	70 cfs
Instantaneous Max: 	3000 cfs                                                                                                                   
Instantaneous Min:  	68 cfs

Time-weighted discharge duration: Discharge during water year 2006 exceeded  
83 cfs 90% of the time and exceeded 987cfs 10% of the time.  The average percent 
difference between the logged discharge and actual field verified discharge was 1%.  The 
average difference between the logged and actual discharge was 5.5 cfs.  This is equal to 
a 1% average drift for the water year.

Rating Summary

Two rating curves were used during water year 2006.  The average percent difference 
between measured and predicted flow for these two ratings was 7.5%.  A high water 
event on December 25th, 2005 exceeded the highest measured discharge for the water 
year 2006 period of record.  However, the associated discharge was within two times of 
the highest measurement and can be considered reliable data. Beginning June 2006 the 
station began showing signs of seasonal cross-sectional filling. The rating was 
subsequently phased through this period to account for the rating transition. The shifted 
rating carries through the end of water year 2006 and into water year 2007.