WSP07787 - Laserfiche WebLink

Home Browse Search

RESOURCE USE For WILDLIFE HABITAT (Con.) Description of Area: Virstin Valley Subevaluation Unit, Arizona, Nevada, Utah Par_ters Unit Pr..ent Conditioua Future Conditioua Pl_1I1.. Alternatives Future 1 I Without 1 2 DISCUSSION OF EFFECTS OF ALTERNATIVE ACTIONS Water quality improvement is directed toward reducing salinity which causes agricultural, municipal and industrial damages. Improvement of irrigation water management has been found to reduce salt loading to the river system in the Virgin River Unit. A consequence of improved irrigation water management is a loss of wetlands which arise from inefficient water management on irrigated lands. A con- flict exists between wetland preservation goals for wildlife habitat and water quality improvement goals. Trade-offs between alternative actions are identified in the tabulations or matrices which follow. The program and nonproject nature of alternative actions prevents site specific identificati~n of proposed improvements for wildlife or wet- land habitat. Participation in the salinity control program is voluntary for irrigators in the study area. Mitigation for loss of wetlands can be accomplished by implementation of a conservation plan of operations for each farm. To the extent it is possible, wildlife habitat will be mitigated by replacement or improvement of habitat of the same kind. ,;~ Wetland habitat loss for Alternative 1 and 2 is primarily wetland induced by irrigation activity. Much of the induced wetlands are adjacent to onfarm and off- farm irrigation ditches and canals. Land adjacent to irrigation induced wetland is often irrigated cropland and upland wildlife habitat. Improvements of wildlife habitat by irrigators is limited to lands they own and lands where habitat improve- ment is practical. Wetlands in the flood plain of Virgin River are subject to flooding, erosion and sedfment deposition. Efforts to improve such wildlife habitat, beyond effects of increased surface flows of the river, do not appear practical. Mitigation of lost wetlands is estimated using equivalent acre-value uplands as a result of the above limitations and conditions in the study area. ,,',~ ",,, ~: Wetlands along Virgin River are estimated at 7,400 acres. Total wetlands, inclUding those outside the impacted area, but within the 2,030 square mile sub- evaluation unit are estimated at less than 10,000 acres, or almost one percent of the total land. The wetlands in this desert and mountain region are very important wetland habitat. Irrigated farm lands have encroached on wetland and adjacent upland wildlife habitat during the past 100 years. Adverse impacts have been offset by beneficial effects of additional food supply created by crops and new habitat along roads, fences and the irrigation water distribution systems. A-22 ,. 4'" .~, j r " ) '- .. '. .