The Napa Watershed Information and Conservation Council connects community and science to
improve watershed health. A great local resource with lots of great information. And they can use your help entering data for Stream Watch here. Volunteers make observations at select creek sites about whether or not there is water in the creek. They also note how much trash they see. This information will be compiled over several years to learn more about our creeks and how we can best take care of them now and as our climate changes.
You can also find information on groundwater here.
A nice map of our upvalley watershed is available here via the same site.