Water Quality and Land Use Changes in the Alafia and Hillsborough River Watersheds,Florida, USA1

Abstract: Spatial distribution of land use can have a substantial effect on surface and groundwater quality. Our objective was to test for trends in flow components and water quality related to changes in land use in the Alafia and Hillsborough River watersheds in Florida, USA, over the period 1974‐2007. In addition, water quality statistics were evaluated in the perspective of numeric water quality criteria and proposed reclassification of segments of the Alafia River. Trends in 10 water quality parameters and three discharge variables were evaluated using a nonparametric trend detection test. Results of land use analysis indicated substantial urbanization and loss of agricultural land in the study area. Discharge variables did not exhibit significant trends, whereas trends in the majority of water quality concentrations were negative or nonsignificant with total nitrogen and total Kjeldahl nitrogen as exceptions showing positive trends. Changes in nutrient pathways could not be clearly identified. Considering recently promulgated numeric nutrient criteria and standards for dissolved fluoride, much of the Alafia River was found to be out of compliance. While there were land use changes and changes in water quality over the study period, it was difficult to identify a direct cause‐effect relationship. Responses to regulatory efforts, such as the Clean Water Act and improvements in phosphate mining practices, may have had greater impacts on water quality than changes in land use.     

WATER QUALITY CONCERNS AND REGULATORY CONTROLS FOR NONSTORM WATER DISCHARGES TO STORM DRAINS1

ABSTRACT: Nonstorm water discharges to municipal separate storm sewer systems (MS4s) are notable for spatial and temporal variability in volume, pollutant type, pollutant concentration, and activity of origin. The objective of this paper was to determine whether current technical knowledge and existing U.S. policy support an improved regulatory approach. The proposed policy would use type of discharge as a regulatory basis, merging the concepts of allowability of de minimis discharges and type-based statewide consistent rules. Specific research objectives were to comprehensively identify discharge types, characterize their prevalence in California, analyze relevant local and regional regulatory guidelines, and systematically evaluate opinions of experts about potential water quality impacts. Results demonstrate nonstorm water discharges were widespread in at least one sector, industrial facilities subject to a state permit; one discharge for every four facilities was reported in 1995, even though the permit explicitly prohibits such discharges. Clear consensus exists for minimal water quality concern for some discharge types when considering both municipal guidelines and experts’ opinions. In particular, condensate from a wide range of equipment and discharges from fire fighting equipment testing were found to be of low concern. Discharge types with consensus high concern were largely limited to discharges prohibited under other regulations, such as wastewater and hazardous waste management controls. Some discharge types where no consensus was identified, such as landscape irrigation, nevertheless generated concern for water quality impacts and appear to be relatively widespread. Available information supports technical feasibility of the proposed policy because at least some discharge types show strong consensus for de minimis impacts among regulatory guidelines and opinions of technical experts.     

BEST MANAGEMENT PRACTICES FOR STORM WATER AND INFILTRATION CONTROL1

ABSTRACT: Water quality controls of storm water runoff and infiltration should be a major part of a nonpoint source control program. Although surface runoff and ground water controls are often approached separately, coordination between the two is essential. For practical reasons, a rather simplified technology-based approach appears to be desirable. Areas affected vary greatly as to their sensitivity to pollution; and the various classes of pollutant source vary greatly as to their potential harmfulness. In effect, a matrix approach appears best, in which both vulnerability of the area and harmfulness of the pollutant source would have weight in determining which level of best management practices (BMP) would be appropriate, whether standard, special, or complete prohibition of the type facility under given circumstances.     

STORM WATER MANAGEMENT: THE CONCEPT AND ITS APPLICATION1

ABSTRACT: Storm water management is a concept being applied in many urban areas to deal with the increasing problems of storm runoff control and flood damage prevention. This paper introduces the concept and describes the recently completed storm water management program in Columbus, Georgia. Columbus has spent five years and over $200,000 in the development of their problem which includes several basic elements: soils inventory and analysis, hydrologic data collection, sediment and erosion control ordinance, storm water management handbook, urban flood simulation model, interdepartment coordination study, drainage problem categorization study, and a pilot basin study. The results of the pilot basin study are presented including example output from the urban simulation model. The computer output illustrates both the hydrologic-hydraulic and economic capabilities of the model.