noxious weeds? or, pretty fall colors by the water? The state of Colorado considers them noxious weeds, and they are in the process of removing all noxious weeds and trees, especially those connected to rivers, creeks, lakes. Why... because they are not native to Colorado, and they take too much water. True, they take water, but, they thrive along rivers, lakes, creeks, canals... they are part of our landscape, have been for hundreds of years. And, imo, if they have thrived here for hundreds of years, grandfather them in. They look beautiful along the waterways. The yellow/orange/red/green is tamarisk. The silverish/pale green/white tree/bush in the upper right (and across the lake) is russian olive, also known as a monkey nut tree.