01P080 – Tenmile Creek above Barrett Lake
Technical Notes:  2005 Water Year

Chuck Springer

The telemetered streamgaging station on Tenmile Creek above Barrett Lake operated 
throughout the water year 2005.  A series of storm events in October and November of 
2004 caused fairly extensive flooding in the Nooksack basin, mainly in the agricultural 
lowlands.  At this station, these events caused noticeable scouring of the channel, 
changing the relationship between stage and discharge.  A large rain on snow event in 
mid January resulted in the highest discharge recorded at this station.  Summer low flows 
allowed substantial aggradation in the stream channel, changing this relationship yet 
again.  A wetter than normal early summer resulted in a minimum summer flow of 2.8 cfs 
(cubic feet per second); twice that of the previous two years of record.

Rating Curve

The range of discharge encountered during the water year was from 2.8 cfs in mid 
September 2005 to over 430 cfs in mid January 2006.  The range of stage encountered 
during the water year was 5.7 feet.  The measured discharge, ranging from 1.6 cfs to  
402 cfs, covers 93% of the magnitude of flows encountered during the water year.  
Discharge rose above the measured range of flows less than 1% of the time during the 
water year.  All low flows during water year 2005 were within the measured range.  Two 
different shifts in the rating curve occurred at this site during water year 2005.  The first 
was caused by channel scouring during the large storm events during the fall and winter.  
The second shift was caused by gradual aggradation that occurred during the month of 
August.  The continuous stage record indicates that the aggradation occurred over 
gradually over time, so this shift was phased in over a period of a month.  Two of the 
discharge measurements taken during water years 2005 and 2006 fell within a range of 
the rating curve that had not previously been measured (measurements taken on April 18, 
2005 and January 17, 2006).   These measurements indicate that previous estimates of 
this range of the rating curve were low.  The rating curve was shifted to reflect these new 
data, and the changes were applied retroactively to the rating curves for water year 2004 
as well.

Stage Record

The station logged continuously throughout the water year without interruption.  Tenmile 
Creek is very low gradient, and fine sediments tend to accumulate around this station.  As 
a result, manual staff gage readings will sometimes differ from the logged stage values by 
a few hundredths of a foot.  During the water year 2005, these variations typically ranged 
from 0.02 feet to 0.05 feet, but were as high as 0.16 feet.  Time weighted corrective 
adjustments were made to the continuous stage record whenever the difference between 
logged and measured stage values resulted in a 5% or more difference in discharge.  All 
adjustments are documented in the Hydstra Data Workbench.



Future Efforts

Cross sectional and longitudinal surveys should be conducted at this site during summer 
of 2006 to aid future modeling efforts, should they be necessary.