Eric .... try the Vertical Casting method at the corners & down current face of the bridge pillars ... especially with rising water levels or in the case of a good constant current flow. The current can force them to seek refuge in the eddy, and occasionally waterlogged timber/brush is also deposited there (which also helps break up the current).
It's not a "do all - be all" method, but it is one that you can often use to coax another fish or two into biting.