City of Boulder Tree-Ring Study
Hydrosphere Featured Project:
City of Boulder Tree-Ring Study
The City of
Boulder’s water supply largely depends on stream
flows in Boulder Creek, which have been recorded since about 1910. These records show that annual stream flow volumes
varied greatly and that droughts of various severity occurred during this period. Until recently, Boulder’s ability to assess
the vulnerability of its water supply system to droughts was limited to this 90-year
period of record. 
Tree-ring records have proven to be useful in extending our knowledge of stream flows back in time and providing valuable insights on the long-term variability of stream flows. This is possible because the widths of individual growth rings of properly selected trees generally mimic the variation of annual flow volumes in nearby streams.
Scientists at Hydrosphere and the National Oceanic and
Atmospheric Administration (NOAA) collaborated to identify several tree-ring records that are well
correlated to natural flows in Boulder Creek and then generated estimates of stream flows
in Boulder Creek that extend back as far as 1703. These
data have provided us with an enhanced perspective on the current drought. They show that this
year’s stream flows are probably the lowest that have occurred during the last 250 to
300 years. They also show
suggest that droughts lasting more than 15 years have occurred several times
within the past 300 years (click to see a graph of the results).
The City of Boulder is using this information to
better assess the adequacy of its water supply system and to improve its drought response
strategies. Taking advantage of the knowledge
gained from tree-rings will undoubtedly benefit other communities throughout the West in
their water supply planning efforts. Please contact Hydrosphere if you'd like more detailed information about this
work.
Other Tree-Ring web sites:
NOAA Paleoclimatology Program Tree-Ring Home Page
Henri D. Grissino-Mayer's Science of Dendrochronology Web Pages
Listen to the KUNC Radio
Interview with Hydrosphere's
Lee Rozaklis. (mp3 file - 2.9M)
Read the Associated Press news story dated
September 23, 2002
as published in the Boulder Daily Camera.
Copyright © 2002 Hydrosphere Resource Consultants, Inc.
