Much Maya research has studied water management, but very little has studied water quality. Water chemistry reflects local and regional geology, soil, and land uses. Thus, it can supply a useful link between past and contemporary environmental conditions. This research analyzes the water quality of sources near archaeological wetland sites in the Three Rivers Region, northwestern Belize to better understand Precolumbian Maya land and water use potentials and possibilities for contemporary water use at these sites. We explore quality complications for crop types, including forests and orchards, as well as paleoenvironmental and modern botanical information to test hypotheses about water limits and possibilities in the region. Our evaluation of water quality also presents implications for domestic consumption of the region's waters and public health. Broad scale results for this region show chemically distinct water sources that include waters that are limited for agricultural and domestic uses, and other waters that are acceptable for these uses. We infer that near surface water chemistry in the lowland part of our study region also changed from the Preclassic into the Terminal Classic Period and beyond due to sea level and concomitant groundwater rise, which had profound impacts on Maya land and water use that continue to the present. In sum, we review Maya Lowlands water quality and present a case study in Belize to understand better the wetland agricultural and domestic use implications influencing this tropical, karst civilization.