www.montereycountynow.com AUGUST 27-SEPTEMBER 2, 2026 MONTEREY COUNTY WEEKLY 17 The Pajaro River and its tributaries are, for the most part, hidden. Despite traversing a few dozen miles throughout Monterey and Santa Cruz counties, the general public typically notices it when they cross a bridge here and there—or when it floods, as it is all too prone to do. The vegetation that grows in and around the river is so thick that it conceals the trickle of water from within, left mostly undisturbed since the levee system was built in 1949. And in areas such as Corralitos Creek in Watsonville, the tributary was essentially shaped by farmers over the decades. When dignitaries gathered along Corralitos Creek in October 2024, the area was unrecognizable. The land around the creek had been cleared, exposing a section of the waterway that for years has been hidden in plain sight. Beyond the wildlife—and the unhoused people—who live in the creekbed, this was the first time many had seen it with their own eyes. The life that surrounds the river is in a constant state of balance. Vegetation provides important habitat for birds, fish and other wildlife that depend on the river for survival. Too much of it, however, can block the river’s flow, and in times of a heavy downpour, that water has to go somewhere—oftentimes breaching the channel and flooding neighborhoods. That October day marked a milestone for the Pajaro River Flood Risk Management Project. After decades of floods, damage and lives uprooted, the project—to at last provide a more secure levee—broke ground. Nearly two years later, work to construct a levee along Corralitos Creek has hit a high gear, clearing more land in the area than ever before and uncovering this natural feature that surrounds communities of tens of thousands of people. As the decades-overdue levee project continues, a group of researchers are finding a way to make life better for both the animals that reside in the river and those responsible for the levee’s maintenance. In summer 2023, the University of California was awarded more than $80 million in grants to support projects that help communities adapt to climate change. Five projects at UC Santa Cruz received grants, including $1.9 million to a team led by Earth and Planetary Sciences Professor Andrew Fisher. Fisher says he has long been interested in how climate change affects the cycle of water, and was thrilled when the grant funds came through. The group of researchers led by Fisher had submitted a proposal for the grant just two months before the Pajaro flood. “It’s serious funding that lets us do something I’ve been dreaming of for a long time,” he says. As the climate warms, more precipitation is falling as water rather than snow. And as recent years have shown, while the total amount of rainfall for a season has remained relatively constant, the storms are increasing in intensity, Fisher says. More land covered by pavement and altered by humans in other ways leads to more runoff heading into rivers and streams, stressing systems, he notes. Case in point is the Pajaro River levee, which crumbled in March 2023 and caused floodwaters to tear through Pajaro, forcing hundreds of people to evacuate and causing countless dollars in damage. When the $599 million funding for the levee project was announced, Fisher organized a group to come up with a plan to gather research on how a levee rebuild project could have further benefits beyond reducing the flood risk. “I had been discussing with regional folks ideas about things that might be done,” he says. “What else could be done to provide benefit? What could be done to improve water quality? What could be done to improve groundwater recharge?” With a team in place, including researchers from CSU Monterey Bay, UC Berkeley, UC Davis and the Resource Conservation District of Santa Cruz County, the group got started in summer 2023. What was originally supposed to be a two-year project was extended by another year. Now, the researchers—a mix of students and faculty—are putting the finishing touches on their study, due to be released for public viewing in the fall. Much of what they learned backed up what they already knew. Other things were surprising. Some people flush their goldfish down the toilet. Others, perhaps more humanely, dump them in the Pajaro River. CSUMB student researchers studying the habitat in the river found the presence of carp—an invasive species that was possibly introduced by someone throwing their goldfish into the water. They know this thanks to environmental DNA (eDNA), a type of technology that’s similar to how forensic scientists find evidence in a crime scene. Using a water, soil or air sample, researchers are able to extract small quantities of degraded DNA from such things as scales and fecal matter, which can give them an idea of what species passed through the area. “It’s often pretty degraded or broken down,” says Liz Alter, an associate professor of biology at CSUMB. “We have to take a lot of precautions to avoid contamination. We often end up with a lot of human DNA, because it’s everywhere. “We also have to be careful about contamination from sewage pipes, because then you’re introducing DNA from what people ate for lunch.” Alter’s lab is heading up the eDNA portion of the overall study to capture a snapshot of the biodiversity in the river. Here, students have taken samples from 10 sites along the river and A levee project focuses on reducing Pajaro’s flood risk. Researchers say the benefits are bigger. By Erik Chalhoub Work on the Pajaro River Flood Risk Management Project is underway along Corralitos Creek in Watsonville. It’s the first phase of a multi-year project to add new levees and rebuild the system constructed in 1949.
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