Mountain snow is a major source of water for people, farms, and nature. To manage water supplies and prepare for floods or droughts, we need to know how much water is stored in the snow. But it’s hard to measure this in the mountains because snow conditions can change a lot from place to place, and there aren’t enough sensors. A new method looks at water pressure under frozen mountain lakes to estimate how much water is in the snow above. We tested this method at Mystic Lake in southwest Montana during a winter with less snow than usual. Even in these difficult conditions, the method gave useful and fairly accurate results. We found that removing noise from the pressure data was very important to reduce errors. Based on what we learned, we created simple steps to help others pick good lake sites and process the data the right way. This approach could help fill gaps in snow measurements, especially in remote mountain areas. With careful planning, it could support better water forecasts and improve how we manage snow-fed water supplies.