In order to determine the source of water, spring water collected directly from the lake bottom springs of Lake Kawaguchi, and measured vanadium concentrations and oxygen and hydrogen stable isotope ratios. Cold and oxygen-rich water discharged from the lake floor that was covered by gravels of 10-50 cm in diameter over the range of approximately 9 m east-west and about 13 m north-south. Oxygen and hydrogen stable isotopic ratios of the lake bottom springs are higher than the groundwater in the southern part of Lake Kawaguchi, showing values close to the groundwater in the northern part of Lake Kawaguchi. The isotope values lies on the local meteoric water line around Mt. Fuji, indicating that the spring water is mainly recharged by rainwater brought from the Misaka Mountains. Vanadium concentrations of water from lake bottom springs are more than double of surface water, suggesting that the lake bottom springs are one of the source of vanadium in lake water in Lake Kawaguchi.