Rahway River migrations. Fish ladders are inundated structures with small underwater steps that allow fish to navigate around a dam and continue their migration. Other approaches include removing obstructions that are inoperative or no longer serve their purpose, or improving water quality and reducing debris that obstructs passage. The fish targeted for upstream passage at the Rahway River Water Supply Dam are alewife (Alosa pseudoharengus), blueback herring (Alosa aestivalis), gizzard shad (Dorosoma cepedianum), white perch (Morone Americana) and the endangered American eel (Anguilla rostrate). Alewife and blueback herring are collectively referred to as river herring due to their similarity in appearance, range,
Fox River (Fish River tributary) tributary of Fox River, known as Blue Rock Creek. I X L Gulch is a small tributary which heads about a mile southwest of Fox River. Slate Creek is another tributary, from the south. Along Fox River, about south of Council, there are several dikes of greenstone that under the microscope are found to be slightly altered diabase. They consist of labradorite and olivine phenocrysts in a groundmass of plagtoclase, augite, and biotite. Some greenstone masses which appeared to be slightly altered tuffs were found in the divide between Fox and Solomon rivers. Fox River (Fish River tributary) Fox River