BOARD01713

• Board Meeting Date: 7/28/2003
• Description: CF Section - Tamarisk Control and Eradication Update
• Board Meetings - Doc Type: Memo

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Impact of Tamarisk Infestation on the
Water Resources of Colorado
May 30, 2003

Research Needs - Several areas of new research and follow-up studies are important
to address for tamarisk control and revegetation in Colorado.

~ Using inventory data and knowledge of control techniques, conceptual long-term
integrated management plans for control of tamarisk and riparian restoration can be
identified for each of the Colorado's major watersheds and by land ownership -
private, state, and federal. This will help to establish a better cost for this work than
could be developed in this report.

~ Existing approaches for a:mtrolling tamarisk and habitat restoration should be
evaluated for their appropriateness and evaluated when field demonstrations take
place. These demonstrations can serve three purposes: I) to document the various
hand and mechanical techniques as to time, cost, efficiency, rate of success, and
safety issues; 2) to document changes to water abundance, water quality, habitat, and
biodiversity; and 3) the demonstrations can serve as an educational tool that provides
visible exposure of the tamarisk issue to the general public.

~ A handbook of appropriate tamarisk control and habitat restoration techniques will
be important to provide to the numerous parties who will work in this area. This
Tamarisk Control and Riparian Habitat Restoration Handbook should be written for
the layman and provide a comparison of techniques, appropriateness, costs, impacts,
expected outcomes, herbicide use, potential future biological controls, safety issues,
etc.

5.0 Threatened Riparian Ecosystems

Photos presented in Figures 13 and 14 represent some valuable insight into the threat that exists
to some of Colorado's more healthy riparian ecosystems. Figure 13 shows the vegetation on Big
Sandy Creek near Hugo, Colorado. This photo was taken on May 30, 2003 and shows a healthy
cottonwood ecosystem that had no infestations of either tamarisk or Russian-olive. Figure 14 is
a photo showing a rather small (less than a couple of acres) infestation of tamarisk on the Big
Sandy approximately 2 miles from the photo in Figure 13. At this stage, the tamarisk is causing
little actual harm. However, the potential exists for a significant spread of the infestation from
this small area when a sizable flooding event occurs in the future. This is due to the prolific
seed source derived from even a small acreage - 500,000 seeds per plant (DeLoach 2002).
Flooding events that dramatically spread tamarisk occurred on the Colorado River during the
flood of 1984 and on the Arkansas River in 1999. It would be relatively easy and cost effective
to eradicate tre Big Sandy infestation now to prevent serious future problems latter. This same
sort of situation undoubtedly exists on many of the major and minor tributaries to Colorado's
rivers.

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