High levels of dissolved SO₄ in drinking water can adversely affect livestock performance. Some plant species may help to remove SO₄ and cleanse drinking water, especially S-hyperaccumulators. However, little is known about the capacity of S-hyperaccumulators to grow in rangeland wetland environments. Here we measured plant properties, S concentration, and S mass of nine plant species. Plants were grown in a wetland environment on an artificial floating island (AFI) in a mesocosm supplied with high SO₄ water (2 430–4 730 parts per million [PPM]) from a rangeland reservoir. Water properties were measured throughout the experiment. We also used our data and data from the literature to parameterize simulations and estimate the number of plants (per L) needed to reduce the SO₄ concentration from 2 000 PPM to a recommended limit of 1 000 PPM. The average sulfur concentration of the nine species was 3.8 times greater than the average of 39 species from the literature. Among the nine species, Brassica napus L., B. napus var. pabularia (DC.) Rchb., and Brassica septiceps (L. H. Bailey) L. H. Bailey tended to have the greatest shoot S concentrations. The total S mass per plant was 5 times greater for B. septiceps (44 mg × plant^–1) than B. juncea (L.) Czern. We found no other appreciable differences in total S mass among species. The simulations suggest that ≥ 1.9 plants × L^–1 of B. septiceps or ≥ 0.6 plants × L^–1 of B. oleracea L. would be needed to reduce the water's SO₄ concentration from 2 000 PPM to the recommended limit. Given the small amount of S removed (per plant) relative to the vast amount of dissolved SO₄ possible in rangeland water sources, planted AFIs are not likely to be a practical tool for reducing SO₄ in livestock drinking water. Conversely, water treatment systems may be justified in some cases.