Figure 11.

Curves representing the solution to Bear's law (1972) for travel times of water through cooling (columnar) joints of various spacings, similar to the range documented by Goehring (2008), as a function of hydraulic heads (i.e., depth from stream bottom to the aquifer). A relatively narrow reference fracture is presented for comparison. Transit times for colloidal material, including nontuberculous mycobacterial (NTM), can be rapid provided there is an integrated network of fractures between the stream bed and the aquifer. See text for discussion.