Board Meeting Memorandum 09/10/2003 ‎(B)‎

• Board Meeting Date: 9/10/2003
• Description: Non Reimbursable Projects Tamarisk Coalition, Infested Acres Inventory
• Board Meetings - Doc Type: Meeting

Non-reimbursable Investment Application-CWCB Construction Fund
Form Revised August 8,2003 •
Tamarisk, also known as saltcedar, is well suited to arid parts of Colorado and has
replaced much of the native vegetation along river and stream banks below 6,500 feet
elevation.
Tamarisk is a tenacious plant that has a deep root system (up to 100 feet) and leaves a
salt residue on the soil surface. These characteristics enable it to quickly replace native
riparian vegetation; e.g., cottonwoods and willows. The resulting tamarisk thickets:
D Increase soil salinity, rendering the soil unsuitable for other plants.
D Have less value as wildlife habitat than native vegetation.
D Widen floodplains by clogging stream channels.
D Impact endangered fish by changing stream morphology.
D Increase fire hazard and intensity.
D Diminish human enjoyment of and interaction with the river environment.
While each of these points is important to one or more constituencies, the single most
critical problem is that TAMARISK STEALS WATER by using more water than native
vegetation that it replaces. This non-beneficial user of Colorado's limited water
resources dries up springs, wetlands, and riparian areas by lowering water tables. As
tamarisk moves into adjacent upland habitats, it consumes even more water as it •
replaces the native grass/sage/rabbit brush plant communities. Based on average
water use values for tamarisk and the native plant species it has replaced, a rough
estimate of the non-beneficial consumption of water by tamarisk throughout Colorado is
approximately 170,000 acre-feet of water per year. These values are above and
beyond what the native vegetation would have consumed and represent enough water
to supply upwards of one million people or the irrigation of nearly 75,000 acres of land.
And every year, the problem only continues to get worse.
The U.S. Department of Agriculture (USDA) has stated that . . . tamarisk infestation has
reached epidemic proportions and is one of the greatest disasters to ever befall native
riparian areas in western United States. The National Invasive Species Council has
identified tamarisk as one of its primary targets, the Colorado Department of Agriculture
has listed it on its noxious weed list, and Colorado Governor Bill Owens has issued an
Executive Order to control tamarisk on public lands within ten years. Although tamarisk
is the primary invasive woody plant (the "poster child" of non-native plants) impacting
Colorado's rivers, other plants, notably Russian-olive co-habit with tamarisk and must
also be considered as a part of any riparian restoration action.
Inventory Need: In Colorado, the area of tamarisk and Russian-olive infestation is
estimated to be approximately 50,000 acres of land, but this is only a rough estimate. A
more accurate inventory of tamarisk and Russian-olive infestation is a crucial element in
the development of control plans at the watershed scale and a determination of its
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