Where are California wetlands?

Wetlands occur in every region of California, from the high Sierras to the deserts of the southwest, and form wherever water collects. They can vary from location to location be found along streams (riverine), in low points with slow drainage (depressional), at the edges of tidal water bodies (estuarine), at the edges of lakes (lacustrine), and around springs (slope).

Overall wetland area is constantly changing due to both natural and human-caused factors. Natural events such as floods, fires, earthquakes and short- and long-term climate change can affect the extent and distribution of wetlands. Wetland losses can occur due to a variety of agriculture, development, and infrastructure activities. Often, these losses are offset by wetland protection and restoration.

Monitoring changes in wetland extent and distribution is critical to effective wetland protection and management. Regular mapping and tracking of restoration activities help environmental managers track change and prioritize locations and types of management actions. The most cost-effective way to map wetlands is using aerial imagery or remote sensing. Interpretation of the images is complex and uncertainties arise from image quality, age and time of year the image was taken, image variability because of climatic conditions, and even the level of experience of the person interpreting the image. Although no maps are perfect, they are immensely helpful for wetlands management. There is currently no comprehensive state wetlands map, and mapping efforts to update existing data are ongoing throughout the state.