This study employed a GIS-based use-analysis on a network of recently mapped pre-Columbian earthworks lying on the west side of a Bolivian floodplain. This wetland region, called Llanos de Mojos, is home to many different types of artificial mounds that served different roles for the ancient communities who constructed them thousands of years ago. This new set of features, which was mapped by volunteers of the Proyecto Sistemas Informaticas Geograficas y Arqueologicas del Beni (ProSIGAB) was purported to be a network of fish weirs, linear earthworks built in rivers or floodplains that are designed to trap fish by exploiting seasonal floodwaters. This identification was based on their similarities with the Baures Hydraulic Complex on the east side of Mojos (Erickson 2000; McKey et al. 2016; Blatrix et al. 2018). Classification procedures made use of the features' physical attributes and relationships with other landscape features to identify them not just as fish weirs, but multi-use structures that connected infrastructure, impounded water, and trapped fish. When understood together with nearby forest island settlements, neighborhoods of agricultural fields, and drainage features, it is argued these earthworks played a substantial role in the lives of past inhabitants, demonstrating their ingenuity by fulfilling multiple functions in a complex anthropogenic landscape.