SWAT Model Recalibration - Tetratech-ffx.com

Beaver Lake SWAT Modeling Baseline Analysis February 12, 2009increase attributable to point sources ( Table 20) and includes increased loading from urban lawns. Theselawns are expected to have a somewhat higher loading rate than pasture because significant amounts ofnitrogen mass are removed from pasture in animal biomass and hay.Table 19.Existing and Future (2055) Upland Nitrogen Loads Delivered to Beaver LakeNameExisting Load(US lbs/yr)Future Load(US lbs/yr)Difference(Future - Existing)Percent ChangeBrush Creek 334,640 316,650 -17,990 -5.4%East Fork 785,050 778,080 -6,970 -0.9%Beaver Lake 634,290 814,740 180,450 28.4%Lower White 424,840 485,930 61,090 14.4%Middle Fork 373,500 364,790 -8,710 -2.3%Richland Creek 762,250 765,880 3,630 0.5%War Eagle Creek 1,943,970 1,908,660 -35,310 -1.8%West Fork 657,570 702,750 45,180 6.9%Total Load 5,916,110 6,137,480 221,370 3.7%Table 20.Sources of Existing and Future (2055) Upland Nitrogen Loads to Beaver LakeSourceExisting Load(lbs/yr)Future Load(lbs/yr)Difference(Future - Existing)Percent ChangeCropland 278,110 231,110 -47,000 -16.9%Pasture 3,392,330 2,350,870 -1,041,460 -30.7%Forest 1,437,470 1,250,500 -186,970 -13.0%Range Brush 396,720 333,280 -63,440 -16.0%Urban Low Density 167,190 1,504,050 1,336,900 799.8%Urban High Density 49,130 116,680 67,550 137.5%Point Sources 195,200 350,990 155,790 79.8%Total 5,916,110 6,137,480 221,370 3.7%Delivered loading rates on a per-acre basis are summarized in Table 21 through Table 23 and provide abasis for comparison among land uses. These rates represent load reaching the lake after all instreamretention processes; thus delivered load rates are generally lower for subwatersheds such as East Fork thatare farther from the lake. The highest delivered load rates occur for the Beaver Lake reporting40