Flows of canal drainage waters into the historically rainfall-driven Everglades have altered the hydrology of this wetland and increased inputs of nutrients and minerals.  We assessed the strength of relationships between plant communities and environmental gradients caused by canal discharges into an oligotrophic, soft-water wetland, the A.R.M. Loxahatchee National Wildlife Refuge.  Macrophyte species composition, soil chemistry, and local hydrology were measured in slough-wet prairie (SWP) habitats at 30 sites located at varying distances from canals that encircle the Refuge.  Soil mineral content and pH declined with distance from the canals, whereas water-depth patterns were more complex and uncorrelated with distance.  Soil nutrient levels were correlated with both distance and depth.  Ordination analysis separated SWP communities across a depth-nutrient axis and a mineral axis, which together explained 86% of the variation in the data.  Accurate predictions of spatial abundance patterns for several species required information from both axes.  Species richness was most strongly and negatively related to soil phosphorus while species evenness was lowest at the deepest sites and those closest to the canal.  Results indicate that Refuge SWP communities are sensitive to water management changes that alter water depth and/or the potential for movement of canal waters into this wetland.