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,
Snake River other conifers. There are also up to 118 species of rare or endemic plants that occur in the Snake River watershed. The Snake River was once one of the most important rivers for the spawning of anadromous fish—which are hatched in the headwaters of rivers, live in the ocean for most of their lives, and return to the river to spawn—in the United States. The river supported species including chinook salmon, coho salmon, and sockeye salmon, as well as steelhead, white sturgeon, and Pacific lamprey. It is known that before the construction of dams on the river, there were three