UC Merced

Abstract Climate variations affect access to recreational opportunities through different mechanisms that influence the provisioning of water and ecosystem services. From 2000 to 2022, Northern and Central California experienced extreme climate fluctuations, with alternating multi‐year dry spells and wet years causing highly variable runoff from the Sierra Nevada into the Sacramento‐San Joaquin Delta. This study assesses how these hydroclimatic variations influence regional recreation by analyzing summer activities (boating, day use) alongside winter activities (birding, waterfowl hunting) at state parks and wildlife areas. The objective is to evaluate how monthly visitor volume and timing shift during drought versus wet conditions, distinguishing between activities directly or indirectly dependent on water resources. During summer droughts with critical low runoff, recreational activity declines sharply; boating drops by 65.8% and day use decreases by 13.8% at state park units. Conversely, winter droughts correlate with increased recreational engagement. Critical low runoff is associated with a 23.4% increase in birding observations and a 50.2% increase in waterfowl hunting takes. This winter increase occurs because restricted wetland resources concentrate waterfowl populations, making them more accessible to visitors. Activities directly dependent on water resources, including recreational fisheries, show the highest sensitivity to runoff fluctuations. We also find that visitor spending is highest during critical drought and wet runoff extremes, reflecting winter demand in drought years, and summer demand in the wettest years. These results highlight the vulnerability of water‐dependent recreation and its economic contributions as climate change accelerates the frequency and magnitude of extreme wet and dry cycles. Plain Language Summary Extreme climate swings in Northern and Central California are shifting how people use the Sacramento‐San Joaquin Delta for outdoor recreation. Between 2000 and 2022, the region toggled between severe droughts and heavy rains, causing massive fluctuations in water flowing from the Sierra Nevada mountains. By analyzing visitor logs at state parks and wildlife areas, this study looks at how these water shifts affect seasonal activities. The impacts depend heavily on the season and whether the activity relies directly on water. During dry summer years, recreation drops sharply: boating visits plunge by 65.8% and general day‐use falls by 13.8%. Conversely, dry winter conditions actually boost activities; bird watching observations rise by 23.4% and waterfowl hunting success increases by 50.2% because shrinking wetlands concentrate wildlife into smaller, more accessible areas. Ultimately, activities tied directly to water are the most sensitive to these changes. As climate change brings more frequent extremes, these unpredictable shifts threaten both the stability of outdoor recreation and the local economies that depend on seasonal tourism. Key Points Boating is negatively affected by seasonally prolonged drought conditions, and positively associated with wet runoff conditions Drought conditions in winter result in increased birding opportunities around populations that are more concentrated to limited wetlands Activities directly dependent on water are more sensitive to changes in runoff than those not directly tied to water resources