This project describes a new method to accurately measure river levels using smartphone sensors. Three pictures are taken that are aimed to the same point on the river's surface and calculations are performed based on the GPS location and spatial orientation of the smartphone for each picture. Augmented reality is used to improve the accuracy of smartphone sensor readings. This proposed implementation is significantly cheaper than existing water measuring systems while offering similar accuracy. Additionally, since the measurements are taken by sensors that are commonly found in smartphones, crowdsourcing the collection of river measurements to citizen-scientists is possible.