No leaves, flowers; probably Populus lanceolata; I'm waiting for spring to be sure. More info here:
Date an estimate. On left.
I know nothing about trees, trying to identify those I see every day along Coyote Creek.
Populus is a genus of 25–35 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar /ˈpɒp.lər/, aspen, and cottonwood.