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1\ I I I' I , I I I 1\ f I I I I I I' I' I BIOLOGICAL OPINION Proposed Action Reclamation routinely dredges two types of areas: sedimentation basins and head works . Reclamation maintains two dredging basins - the Topock Dredge Basin located near Needles, California, and the Laguna Dredge Basin, located between Imperial and Laguna Dams. In addition, Reclamation routinely dredges material from the headworks of the All-American Canal and the Gila Gravity Main Canal at Imperial Reservoir. These dredging operations are confined to the areas mentioned above. The dredging uses a hydraulic dredge, and the material is deposited on spoil areas proximate to the dredging basins. In the case of the headworks of the All-American Canal and the Gila Gravity Main Canal, the dredged material is deposited into the California Sluiceway below Imperial Dam and sluiced to the Laguna Dredge Basin for removal. 7. Yuma Desalting Plant Minute 242 defines the salinity requirements of Colorado River water delivered to Mexico. A salinity monitoring program is conducted at points below Parker Dam to the NIB. Computations are made projecting the annual salinity requirements from these data. If necessary, actions are taken to reduce salinity, such as reducing drainage pumping, or operating the Yuma Desalting Plant (YDP). Operating the YDP for salinity control is not expected to occur within the next five years. The BA addresses discretionary one-third operation of the YDP. Discretionary operation of the YDP at one-third capacity may occur to market approximately 26,200 acre-feet of the 110,000- 132,000 acre-feet of water currently discharged annually to the Cienega de Santa Clara, a marsh complex located in Sonora, Mexico, near the Sea of Cortez. The one-third operation is addressed programmatically in the BA, because a specific plan and agreement for marketing the desalinated water have not been completed at this time. Reclamation will initiate a new consultation if and when a specific marketing proposal is quantified. 8. 5-Mile Zone The 5-mile zone is a 36,000-acre area 10 miles south of Yuma, Arizona, containing Reclamation- acquired and other lands needed to construct, operate, and maintain a well field providing water to Mexico in partial fulfillment of the 1944 Treaty with Mexico and as required by Title I of the Salinity Control Act. Reclamation's discretionary activities in the zone are limited to maintaining the 21 wells in the well field, ingress and egress routes, the associated delivery canal, and the YDP sludge disposal site. 9. Endangered Species Conservation Activities Reclamation has discretion in conducting the types of activities that are beneficial to threatened and endangered species under section 7(a)(l) of the ESA. Under the ESA, Reclamation and other Federal agencies are permitted to: 28