Tide gates are one-way doors integrated into dyke systems that prevent saltwater intrusion to agricultural land and allow freshwater drainage to the estuary during low tide. Tide gates may act as fish passage barriers for juvenile salmonids, limiting movements during migration and access to rearing habitats. We conducted our research in Coos Bay, one of the many Oregon estuaries with extensive use of tide gates. Our objectives were to 1) develop a methodology for recording fish passage at tide gates 2) describe the conditions under which fish passage occurs and 3) compare fish passage behavior between a top-hinged tide gate, a side-hinged tide gate and a non-gated stream. We installed stationary passive integrated transponder (PIT) antennae around a top-hinged gate, a side-hinged gate and in a non-gated reference system to track the movement of PIT tagged juvenile coho salmon. Our results indicate that coho salmon smolt passed upstream most frequently at the non-gated channel (48% of all smolts detected), than the side-hinge gated site (28%) or the top-hinge gated site (3%). Subyearling coho salmon passed more frequently at a specific range of gate angles and tailwater depths at both top hinged and side-hinged tide gates. Smolts preferred greater gate angles and tailwater depths than average to pass downstream at both tide gates. Subyearlings passed upstream more frequently during small gate angles and a narrow range of tailwater depths at the top-hinged gate but did not display preference for a particular condition at the side-hinged gate. At the top-hinged gate, conditions favorable for subyearling upstream passage occurred towards the end of the gate open period and therefore subyearlings were severely limited in their opportunities for passage. In addition to these direct physical effects on juvenile salmonid passage, tide gates also seem to influence fish migratory timing by altering environmental conditions around them.