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i78G United States Department of the Interior BUREAU OF RECLAMATION Upper Colorado Region Western Colorado Area. Office RECEIVED FEB 01 2001 2764 Compass Drive, Suite 106 Grand Junction CO 81506-8785 I JAN 3 ~, Z1M' 835 E 2nd A venue, Suite 39s!orado Water Conservation Board Durango CO 81301-5475 WCD-KLashmett ENV 7.00 Subject: Summer Test Flows, San Juan River Dear Interested Party: The Bureau of Reclamation (Reclamation) is in the process of developing a plan and environmental assessment for conducting the subject test. The reason Reclamation is proposing this test is to obtain accurate, on the ground, information on the effects a reduced summer release from Navajo Dam (dam) may have on the downstream affected environment. This information will be incorporated in an environmental impact statement (ElS). The ElS, which is currently being prepared, addresses changes in dam operation due to the San Juan River Basin Recovery Implementation Program flow recommendations. The test would be conducted after the spring run-off and once the irrigation season was in full operation, most likely in late June or early July 200 I. Releases from the dam will be reduced at incremental levels to a minimum of 250 cfs. This is approximately half the flow that would normally be released from Navajo Dam during the summer. .This flow will be maintained for 5 to 10 days during which time Reclamation would collect physical, chemical and biological data associated with river flow as far downstream as Shiprock, New Mexico. Reclamation will prepare a draft environmental assessment describing the impacts of the proposed test on the affected environment. This draft will be submitted for public comment in the near future. Any comments or concerns will be addressed in the final environmental assessment. Once the test is underway, it is expected that the full effect of the flow reduction at Shiprock will take about 2 days. At that time, a wide array of data will be collected including: . Aerial photography from the dam to the confluence of the Animas River. . Water temperatures will be monitored at six locations from the dam to the Hammond Diversion. . A qualitative assessment will be made of physical changes in the river from the dam to the Animas River through both floating the river and by vehicular access. This will include an assessment of river navigability, reductions in usable aquatic habitat and the ground water supply to wetland/riparian vegetation. . Changes in river will be monitored at several locations along the river. . Flow data will be collected from several existing river gage stations located on the river. . Water quality samples will be collected at several locations on the river.