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

Impacts: Impacts are: 1) Very effective at removing tamarisk in a mixed vegetation stand
without killing other valuable plants. 2) Requires a terrain that is relatively level and accessible.
3) The mulched materials provide a suitable seedbed for revegetation. and 4) Some spot
herbicide re-application will be necessary.

Applicability to Colorado: Much riparian lands and adjacent uplands in Colorado could be best
controlled with mechanized mulching equipment. An approach that shares this specialized
equipment with many different communities and agencies could be an efficient use of minimum
financial resources.

Other Mechanical Equipment

Effectiveness: Other mechanical equipment, such as D- 7 dozers with brush bars to remove the
above ground vegetation and root plows for below ground vegetation, has been successfully used
at the Bosque del Apache National Wildlife Refuge in New Mexico. Some follow-up
mechanical clearing is generally necessary. This approach does not use herbicide.

Costs: Approximately $800 per acre.

Impacts: Impacts are: 1) Not very effective at removing tamarisk in a mixed vegetation stand
without killing other valuable plants. 2) Requires a terrain that is relatively level and accessible.
and 3) The soil surface is severely disturbed and requires active revegetation

Applicability to Colorado: It is unclear if there are lands in Colorado that could best be
controlled with this type of large equipment.

Hand Cuttin2

Effectiveness: Hand work using chainsaws for the cut-stump approach is a successful method of
controlling tamarisk.

Costs: Hand work is extremely expensive with an average cost of several thousand dollars per
acre and can be as high as $5,000 per acre. .

Impacts: Impacts are: 1) Very effective at removing tamarisk in a mixed vegetation stand
without killing other valuable plants. 2) Is most appropriate for rough terrain that is not
accessible by mechanical equipment. 3) The cut materials must either be stacked and burned,
chipped, or left in piles for wildlife habitat. and 4) Some spot herbicide re-application will be
necessary.

Applicability to Colorado: In western Colorado, hand clearing of tamarisk has been used in
canyons, washes, irrigation ditches, and along steep river banks. These same type areas
throughout Colorado would be appropriate for hand work.

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