As we do every spring on many of the rivers in California, we are currently using rotary screw traps to enumerate outmigrating juvenile salmon – but this year, you could say conditions are less than ideal. Over the past week or so, many of the rivers in California’s Central Valley have been running high. Water operators temporarily increase flows in the rivers for a “spring pulse flow” to assist outmigrating salmonids in making their way out of the tributaries and through the Sacramento San Joaquin Delta. As a result of the current drought, rivers like the Tuolumne have remained low throughout the year, allowing invasive water hyacinth to multiply exponentially (as seen in this dramatic video). To combat the onslaught of floating debris at the increased flows, FISHBIO technicians have been working around the clock at some of our monitoring sites to keep the traps operating. This is a good example of the impact that invasive species like water hyacinth can have on what used to be a routine activity.