handling of sites w/ negative flows

need to decide how we want to handle sites w/ negative flows.

found 1 example site: 01651730

on WaterWatch no site-level plots are produced for that site although it definitely exists and in state summaries the site and latest flow information is provided via WaterWatch

another example site w/ negative flows is: 01482100

same situation where WaterWatch lists the site but won't generate any site-level plots for it