Much of the salts come from decades of excessive agricultural runoff from beyond wasteful irrigation practices that still continue to this day. Mainly because Colorado river water rates were way under market value in the 30's when they were first established and have barely changed ever since, making them wildly ridiculously undervalued today. If CA farmers were charged realistic market rates then they might be incentivized to improve their irrigation practices which would pretty much solve the "water crises" as well as stop increasing the poisoning of the Salton Sea.