Find a couple deep hole up river from the zoo. Fish these hole using eggs with very little wieght. If the water is slow enough 1 small split shot will work. Ive taken many spring and fall chinook this way.

Not every hole will hold springers. There are a few things to look for will trying to find a "good" salmon hole. Look for rock shelves that drop into deep water. Salmon are lght sensitive and they gravitate to places that provide shade. Also look for deep boily back eddies at the top of a deep pool, the turbulent water gives the fish a sense of security and they will hold in there.
Springers are wierd when it comes to the "bite", All of a sudden they will turn on than just as fast they shut down. There will always be the occasional biter, You just have t be presitant and keep after them. Also try using different scents. Anise is by far my favorite for springers. shrimp/prawn and sardine are also good bets.
Hope this helps