The primary risk associated with El Niño in Marin County is flooding, which could affect homes, businesses, and transportation networks. Low-lying areas and regions near rivers and streams are especially at risk. Residents may face disruptions to daily life, including road closures and potential evacuations. The increased rainfall could also lead to soil erosion and landslides in hilly areas, further compounding the challenges. Local officials are urging residents to stay informed and take necessary precautions to minimize risks.