9417

• UCREFRP Catalog Number: 9417
• Author: U.S. Department of the Interior.
• Title: Final Environmental Assessment
• USFW Year: 1998.
• USFW - Doc Type: Acquisition and Enhancement of Floodplain Habitats along the Upper Colorado, Green, and Gunnison Rivers as part of the Recovery Program for Endangered Colorado River Fishes.
• Copyright Material: NO

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these properties there will be no increase in mosquito production.

There will be some properties with gravel pits or ponds. These pits and ponds already hold water
year-round. Excavation (e.g., levee breaching) to connect these to the river is expected to reduce
mosquito production because fishes will be able to come in from the river and feed upon mosquito
larvae.

Some properties will have shallow floodplain depressions. During spring runoff these depressions
often fill with tea-colored sub-up groundwater, resulting in prime mosquito habitat. Connecting
these to the river is expected to reduce mosquito production by allowing the depression to fill with
muddy, turbid river water, and by allowing access to fishes which feed upon mosquito larvae.

Some of the properties will be floodplain terraces. During spring runoff these terraces will become
inundated with river water; as runoff subsides they will drain and become dry. If these properties
do not have levees, then simply acquiring easements will have no effect on mosquito production.
On floodplain terrace properties where there are levees and those levees are breached, then the
surface area of inundation will be increased during runoff when river water flows over the property.
In this case mosquito production may increase. The site will be covered with muddy river water,
however, which is less conducive to mosquito production; and the site will be accessible to fishes
which eat mosquito larvae.

b. What will be done to control mosquitos?

Recovery Program staff and Fish and Wildlife Service staff will work with Mosquito Abatement
Districts and others to identify viable approaches that will effectively control mosquitoes, that will
not adversely affect endangered species, and that are cost-effective. The Utah Department of Natural
Resources, in cooperation with the Recovery Program, organized a task force (chaired by the Utah
State University Cooperative Extension Service) to resolve mosquito issues and to identify
mosquito-control strategies for the Green River within Uintah County, Utah. A similar task force
will be organized to address mosquito issues within the proposed project areas of Colorado.

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