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application timing prior to storm events(Linde and Watschke 1997;Groffman et. <br /> al 2004;Schuman 2004).As such,these values tend to be conservative <br /> estimates of potential fertilizer derived nutrient contributions in typical wet- <br /> season,urbanized runoff.Because relatively little information exists for the exact <br /> contribution of fertilizer in urbanized runoff,especially for the Tampa Bay <br /> watershed,a range of values from 10%(conservative)to 79%(liberal)were used <br /> to develop estimates of reductions associated with a rainy season prohibition of <br /> fertilizer application. <br /> Estimated Compliance of Fertilizer Ordinances <br /> Likewise,with the recent enactment of new fertilizer ordinances in several <br /> municipalities in Florida(Lee,Charlotte,Sarasota,and St.Johns counties,and <br /> the city of Sanibel)(TBEP 2008)in 2007 and 2008,information regarding <br /> expected compliance rates of fertilizer application prohibitions—if the ordinance <br /> includes these stipulations—has not yet been generated.These enacted <br /> ordinances rely strongly on education of the public and retail fertilizer sales <br /> outlets to convey the proper fertilization maintenance schedules to their <br /> customers in order to achieve compliance of any prohibitions.Recently the <br /> Florida Department of Environmental Protection(FDEP 2008)provided for load <br /> reduction credits(55%)to be granted towards efforts that could include fertilizer <br /> application education;however,the expected rates of implementation and <br /> compliance of any educational efforts was still widely unknown. <br /> In Minnesota,regional and state phosphorus fertilizer restriction laws were <br /> enacted in 2004 and 2005,respectively(MDA 2007).In 2006,it was estimated <br /> that phosphorus fertilizer use(in tons)decreased by 48%after adoption of these <br /> laws.Much of these anticipated reductions in use were associated with the <br /> replacement and availability of phosphorus-free fertilizers at retail sales outlets. <br /> As of this writing,no other estimates of expected compliance rates for fertilizer <br /> ordinance implementation are known for similar rule enactments prohibiting the <br /> use of nutrient fertilizers. <br /> Based on the available information regarding expected compliance rates and <br /> changes in use associated with the enactment of fertilizer prohibitions,a range of <br /> values from 10%(conservative)to 75%(liberal)were used to develop estimates <br /> of compliance rates across urbanized land uses where fertilizer application would <br /> be expected.These compliance rates were applied to the urbanized areas of the <br /> Tampa Bay watershed for wet-season estimates of N loads in combination with <br /> the expected reductions associated with the varying percent contributions of N <br /> fertilizer to urbanized runoff as described above. <br /> OBJECTIVES <br /> Determine the range of expected nitrogen load reductions associated with <br /> fertilizer restriction implementation according to the TBEP regional <br /> recommendations which include a June 1—Sept.30 rainy season prohibition of <br /> nitrogen fertilizer application. <br /> 5 <br />