 Ultimately, the Navajo reached an agreement with the city and the power plant was approved for construction in 1986, with the first power generated in 1989.Navajo Dam has greatly changed the ecology of part of the San Juan River, from a warm, muddy and highly seasonal river to a cold-water stream with relatively constant flow.The dam's impacts are most pronounced in the stretch above Farmington (where the San Juan is joined by the mostly undammed Animas River and regains some of its seasonal variations); further downstream, the dam "apparently has had no significant effect" on the river channel and sediment flow.