Peace and Myakka River Water Quality Summary 2002 - Southwest ...

3.3 ANNUAL FLOW-ADJUSTED LOADSWatershed managers can gain additional insights into spatial and temporal pollutantdischarge patterns by examining the annual ‘flow-adjusted’ loads of important waterquality constituents that are discharged from gaged sub-basins.These values are calculated by dividing a sub-basin’s estimated annual constituent load(in milligrams) by its measured annual discharge (in liters). The result, expressed inunits of mg/L, gives an estimate of the mass of the constituent that was discharged fromthe sub-basin per unit water flow.In cases where managers wish to reduce loadings of a particular constituent to areceiving waterbody, the most cost-effective approach is often to focus on areas thatexhibit the highest flow-adjusted loads of that constituent. If effective load reductionmethods are available, projects implemented in those areas should tend to produce thelargest load reductions per volume of water treated.Estimated annual flow-adjusted loads of nutrient forms and TSS from gaged sub-basinsin the Peace and Myakka River watersheds are summarized, for water years 1998 –2001, in Figs. 11-17.For dissolved inorganic nitrogen forms, the largest estimated flow-adjusted loads (>0.3mg N/L) occurred at the following monitoring stations:• Joshua Creek at Nocatee (water years 1999, 2000, and 2001)• Peace River at Zolfo Springs (1998-2001)• Big Slough Canal near Myakka City (2000)• Peace River at Arcadia (1998-2001)• Peace Creek Canal near Wahneta (2000).For dissolved inorganic phosphorus, the largest estimated flow-adjusted loads (> 0.4 mgP/L) were observed at the following stations:• Peace River at Bartow (1999, 2001)• Peace River at Fort Meade (1998 – 2000)• Peace River at Zolfo Springs (1998 – 2001)• Charlie Creek near Gardner (1999)• Peace River at Arcadia (1998, 1999, 2001)• Myakka River near Sarasota (2001)• Big Slough Canal near Myakka City (2001).For TSS, the largest estimated flow-adjusted loads (> 25 mg/L) were observed at thefollowing stations:• Saddle Creek at Structure P-11 (1998, 1999, 2000)• Peace River at Bartow (1999, 2000)42