A major objective of the CSS is to develop a long-term index of transport to inriver smolt-to-adult survival rates for Snake River hatchery and wild spring/summer Chinook and steelhead. Smolt-to-Adult return ratio (SAR) is the survival from a beginning point as a smolt to an ending point as an adult. SARs are calculated from LGR to LGR and can also be estimated at BON to BON or LGR, or below BON to BON.