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Urban Water Qualitv and Fertilizer Ordinances:Avoidina Unintended Conseauences:A Review.... 5 zone of Lake Mendota had less P than leaves and fertilizer.Another third of the N came in as collected from the ground surface near the shore.In combustion products.20%of the N accumulated in heavily canopied communities,leaves can be greater the watershed and the main avenue for N loss was sources of P than lawns(Baker,2007). atmospheric with only 3%of the N leaving in the surface water.The Arizona study identified several These studies on the subject of nutrients from topics in need of research including dry deposition plant debris point to two conclusions: First,there is processes,soil N dynamics,and denitrification losses. considerable potential nutrient load from plant debris in the urban environment that can add significant Take-home message for nutrient sources amounts of nutrients to the storm water. Second,plant and Impacts debris should be removed from impervious surfaces (street sweeping,blowing)or mulched and put back The brief literature review above clearly into the lawn with mulching mowers as soon as documents the complexity of eutrophication of inland possible because water(rain)can easily and rapidly and coastal water bodies.Land-based nutrient(N and extract nutrients from the leaf debris. P)sources are important in the nutrient loads to the water bodies,and there are many distinct nutrient Urban watersheds.In a Baltimore,Maryland sources.These sources undergo changes and interact study,Grollman et al.(2004)measured increased with the environment in route to a water body.Once nitrate losses from urban and suburban watersheds in the water body nutrients play a role in complex (approx.2 to 7 lb per acre per year of N)compared nutrient cycling that maintains nutrients in forms with a forested watershed(less than 1 lb per acre per suitable for algal growth.Controlling nutrients at the year of N).These researchers also noted high source is a sound approach to reducing nutrient retention(75%)of N inputs in the urban watersheds loading to water bodies,but nutrient sources and fates mostly consisting of fertilizer and atmospheric are complex processes(Alcock,2007).Due to the deposition.In other studies of urban turf and forested myriad of sources and their complex interactions, landscapes in Baltimore,researchers noted that source reduction requires a comprehensive and grasslands exported more N than forests,but the careful approach. urban grasslands(turf)had significant ability to retain N(Groffinan et al.,2009).The authors found that,in Section 2. Relationship of lawn some instances,unfertilized urban turfgrass lands had fertilization to leaching and runoff more leaching losses than fertilized grasslands.The from landscapes authors emphasized that changing from agricultural land to urban grasslands would have N-load benefit In this section we examine several important for reducing N losses to the Chesapeake Bay issues relative to fertilization,leaching,rainfall, watershed.In a study of urbanization impacts on irrigation,soil,and runoff.We present the water quality in small coastal watersheds,Tuffurd et information from national research studies on several al.(2003)found that dissolved organic nitrogen questions: (DON)and P-containing particulates were the dominant sources of these nutrients and there was What role does healthy turfgrass play in the variation in location and season.For instance,in the urban environment?Will unhealthy summer,DON from forested wetland creeks and P turfgrass lead to increased nutrient losses from urban ponds dominated.These authors and when? concluded that broad land-use or land cover classes •How might various urban soil types and should not be used to predict nutrient concentrations qualities impact the effectiveness of in streams of small watersheds.Baker et al. (200 1) landscape fertilizer management? calculated an N balance for the central Arizona-Phoenix ecosystem.They determined that •How might rainfall patterns and amounts humans controlled as much as 88%of the N inputs; affect fertilizer nutrient leaching and runoff half of the total N was imported by humans as food before,during,or after the summer growth period? � 3 . i2