Evaluation of resource-efficient landscape systems to reduce contaminants in urban runoff

Urban non-point source pollution and the high cost of urban water treatment have generated interest to identify sources of pollution and to develop cost-saving preventive measures. A series of micro-landscape systems planted with either conventional vegetation or Resource Efficient Plants (REP ^™) was constructed in Dallas, TX to assess the contribution of stormwater runoff from residential landscapes into local nonpoint source pollution, and to quantify the impact of alternative best management practices. The conventional landscapes, receiving high inputs of fertilizer, herbicide and irrigation, produced significantly higher levels of nitrate nitrogen, orthophosphate and 2, 4-D in runoff. Stormwater runoff volume was also significantly higher under irrigated conditions. In contrast, the REP ^™ landscape systems had lower levels of stormwater runoff and the concentration of nitrate nitrogen and orthophosphate in runoff was consistently very low, suggesting that fertilizer usage in residential landscapes poses little water quality risk. Levels of 2, 4-D in runoff were below federal drinking water thresholds. Reduced irrigation and chemical inputs made possible by REP^™ significantly reduced this risk. Conventional landscapes scored higher for visual ratings throughout the 3 year study period than did alternative REP^™ landscapes, indicating that drought resistant plants of both turfgrass and ornamental plants with better appearance are needed for widespread public acceptance of REP ^™ landscape systems.