SYNOPTIC CHANGES OF SALINITY, NUTRIENTS, AND ARSENIC IN DRAINAGE CHANNELS FEEDING INTO BOMBAY BEACH WETLANDS, SALTON SEA AREA, CALIFORNIA

New wetlands have emerged near the north shore of Salton Sea, California in the Bombay Beach area. These wetlands appear where significant terrestrial water sources are present. The perennial source of water is a thermal artesian aquifer that supplies recreational spas and fish farms via artesian wells. Waste flows from these spas and farms feed into local channels, providing a constant water source to the wetlands. The artesian wells, ranging from 110 to 300 meters deep, yield water at temperatures between 55 and 80 degrees Celsius, with higher temperatures at deeper wells. Groundwater salinity from these wells ranges from 4100 to 5200 mg/L total dissolved solids, with a consistent sodium-chloride signature. Isotope analysis indicates the water is locally derived (-71 del D and -8.7 del O18) and not sourced from imported Colorado River water which is much lighter isotopically. Some of the channels collecting waste discharges from the fish farm and hot spas have constantly increasing salinity downstream, up to 2.5 times higher, while others show no change in salinity downstream. A model of terrestrial salinization is proposed to explain these variations. Fish farms contribute notable amounts of nutrients (N and P) to the drainage channels, but other thermal spa discharges do not significantly add N or P. Synoptic changes in the channels result in ammonia loss, nitrate gain, and enrichment of phosphorus and arsenic due to various processes including plant uptake, nitrification, and simple evaporative enrichment. Increasing salinity, nutrients, and arsenic in some channels feeding into the Bombay Beach wetlands may present risks to aquatic species and migratory waterfowl in the area.