Aptos Creek Lagoon, located on California’s Central Coast in Santa Cruz County, is a small seasonal estuary where Aptos Creek flows into the Pacific Ocean. Spanning less than half a mile and part of a 25-square-mile watershed, the lagoon receives an average annual rainfall of 25 to 30 inches, primarily during winter storms. Seasonal sandbar formation at the mouth creates a dynamic brackish environment, influencing water levels, salinity, and oxygen availability.

The lagoon serves as a critical habitat for steelhead trout and other aquatic species, providing a nursery for juveniles and a migratory corridor for adults. However, human activities, such as urban runoff and development within the watershed, can impact water quality and sediment dynamics, altering the lagoon's natural processes. Conversely, the sandbar closures pose challenges for flood management, as water levels can rise during the wet season, affecting nearby infrastructure and properties.

Real-time water level monitoring at Aptos Creek Lagoon provides key insights into the interactions between natural processes and human influences. This data supports habitat conservation efforts, guides flood mitigation strategies, and helps manage the balance between ecological health and human impacts in this sensitive coastal system.