Figure 12.  Aluminum and iron colloids in Daisy Creek.  View is upstream with surface-inflow site 481 on left side of stream.  Upstream of site 481, the pH of Daisy Creek is greater than about 4.5, and white aluminum colloids form.  Inflow (pH of 2.85) from site 481 decreases pH in Daisy Creek to less than 4.5, and only orange iron-oxyhydroxide colloids form. (Photograph by J.H. Lambing, U.S. Geological Survey).