Briarwood Stormwater Pollution Load Reduction Report

The Briarwood Stormwater Treatment Facility (BSTF) was completed in 2012 in Venice, FL. Designed to treat surface water from a 65-acre wet detention pond between storm events, the treatment train includes physical and biological processes to reduce nitrogen loads to Alligator Creek. Water quality parameters are monitored monthly at BSTF to provide estimates of pollutant load reduction efficiency and inform on optimal operations. The results of the removal of total nitrogen and select nutrients are reported annually in the Sarasota County NPDES MS4 Annual Report.

Pollutant Load Reduction Reports

Pollutant Load Reduction Reports for the Briarwood Stormwater Treatment Facility are updated at least bi-monthly. These reports are generated utilizing water quality and flow data to calculate the estimated nitrogen load reductions for each month. The tables below contain the most recent 12 months of calculations. Reports are available for download for the entire period of record.

BOD, Biochemical oxygen demand

BSTF Pollutant Load Reduction Report for "BOD, Biochemical oxygen demand"
Year / Month Rainfall In (Wet well / Pump A) Out (Wet well / Pump B) Reduction Goal Percent Volume
Lost		 Percent BOD
Reduction
SARASOTA_ARMS - AL-1 (in) Volume (kgals) BOD conc. (mg/l) BOD load (lbs) Volume (kgals) BOD conc. (mg/l) BOD load (lbs) BOD (lbs) BOD (lbs)
2025 December 0.34 6,198 7.190 371 5,741 3.350 160 211 7.4 % 53.4 %
2025 November 0.06 4,253 5.240 185 5,738 3.890 186 -1 -34.9 % 25.8 %
2025 October 0.83 18,677 7.330 1,142 16,603 5.560 770 372 11.1 % 24.1 %
2025 September 1.61 14,354 4.880 584 14,982 4.700 587 -3 -4.4 % 3.7 %
2025 August 10.19 23,367 5.130 1,000 23,014 3.430 658 342 1.5 % 33.1 %
2025 July 2.65 17,547 5.010 733 17,743 1.350 199 534 -1.1 % 73.1 %
2025 June 12.50 5,481 5.090 232 5,191 4.120 178 54 5.3 % 19.1 %
2025 May 2.04 26,427 9.650 2,128 22,497 7.890 1,481 647 14.9 % 18.2 %
2025 April 1.18 9,702 7.110 575 6,142 8.280 424 151 36.7 % -16.5 %
2025 March 1.53 0 6.510 0 1.000 84.6 %
2025 February 1.65 58 5.470 2 1 1.000 0 2 98.3 % 81.7 %
2025 January 1.19 0 3.970 0 1.000 74.8 %
Totals 35.77 126,064 72.580 6,952 117,652 45.570 4,643 2,309 13.5 % 39.6 %

Chlorophyll a, corrected for pheophytin

BSTF Pollutant Load Reduction Report for "Chlorophyll a, corrected for pheophytin"
Year / Month Rainfall In (Wet well / Pump A) Out (Wet well / Pump B) Reduction Goal Percent Volume
Lost		 Percent ChlaC
Reduction
SARASOTA_ARMS - AL-1 (in) Volume (kgals) ChlaC conc. (mg/l) ChlaC load (lbs) Volume (kgals) ChlaC conc. (mg/l) ChlaC load (lbs) ChlaC (lbs) ChlaC (lbs)
2025 December 0.34 6,198 0.017 0 5,741 0.004 0 0 7.4 % 76.5 %
2025 November 0.06 4,253 0.088 3 5,738 0.006 0 3 -34.9 % 93.2 %
2025 October 0.83 18,677 0.124 19 16,603 0.076 10 9 11.1 % 38.7 %
2025 September 1.61 14,354 0.171 20 14,982 0.125 15 5 -4.4 % 26.9 %
2025 August 10.19 23,367 0.022 4 23,014 0.120 23 -19 1.5 % -445.5 %
2025 July 2.65 17,547 0.021 3 17,743 0.018 2 1 -1.1 % 14.3 %
2025 June 12.50 5,481 21.700 992 5,191 5.100 220 772 5.3 % 76.5 %
2025 May 2.04 26,427 29.900 6,594 22,497 163.000 30,602 -24,008 14.9 % -445.2 %
2025 April 1.18 9,702 39.200 3,173 6,142 22.000 1,127 2,046 36.7 % 43.9 %
2025 March 1.53 0 46.800 0 0.465 99.0 %
2025 February 1.65 58 27.000 13 1 0.618 0 13 98.3 % 97.7 %
2025 January 1.19 0 58.600 0 1.750 97.0 %
Totals 35.77 126,064 223.643 10,821 117,652 193.282 31,999 -21,178 13.5 % -18.9 %

Nitrogen, Kjeldahl

BSTF Pollutant Load Reduction Report for "Nitrogen, Kjeldahl"
Year / Month Rainfall In (Wet well / Pump A) Out (Wet well / Pump B) Reduction Goal Percent Volume
Lost		 Percent TKN
Reduction
SARASOTA_ARMS - AL-1 (in) Volume (kgals) TKN conc. (mg/l) TKN load (lbs) Volume (kgals) TKN conc. (mg/l) TKN load (lbs) TKN (lbs) TKN (lbs)
2025 December 0.34 6,198 3.720 192 5,741 2.410 115 77 7.4 % 35.2 %
2025 November 0.06 4,253 2.960 105 5,738 1.960 93 12 -34.9 % 33.8 %
2025 October 0.83 18,677 3.080 480 16,603 1.620 224 256 11.1 % 47.4 %
2025 September 1.61 14,354 1.980 237 14,982 2.050 256 -19 -4.4 % -3.5 %
2025 August 10.19 23,367 2.620 510 23,014 2.080 399 111 1.5 % 20.6 %
2025 July 2.65 17,547 3.400 497 17,743 1.930 285 212 -1.1 % 43.2 %
2025 June 12.50 5,481 3.730 170 5,191 3.830 165 5 5.3 % -2.7 %
2025 May 2.04 26,427 4.820 1,063 22,497 4.290 805 258 14.9 % 11.0 %
2025 April 1.18 9,702 4.950 400 6,142 4.480 229 171 36.7 % 9.5 %
2025 March 1.53 0 1.350 0 0.685 49.3 %
2025 February 1.65 58 4.010 1 1 0.980 0 1 98.3 % 75.6 %
2025 January 1.19 0 4.310 0 0.623 85.5 %
Totals 35.77 126,064 40.930 3,655 117,652 26.938 2,571 1,084 13.5 % 33.7 %

Nitrogen, Nitrite + Nitrate as N

BSTF Pollutant Load Reduction Report for "Nitrogen, Nitrite + Nitrate as N"
Year / Month Rainfall In (Wet well / Pump A) Out (Wet well / Pump B) Reduction Goal Percent Volume
Lost		 Percent NOx
Reduction
SARASOTA_ARMS - AL-1 (in) Volume (kgals) NOx conc. (mg/l) NOx load (lbs) Volume (kgals) NOx conc. (mg/l) NOx load (lbs) NOx (lbs) NOx (lbs)
2025 December 0.34 6,198 0.024 1 5,741 0.009 0 1 7.4 % 62.5 %
2025 November 0.06 4,253 0.026 0 5,738 0.010 0 0 -34.9 % 61.5 %
2025 October 0.83 18,677 0.027 4 16,603 0.018 2 2 11.1 % 33.3 %
2025 September 1.61 14,354 0.023 2 14,982 0.020 2 0 -4.4 % 13.0 %
2025 August 10.19 23,367 0.031 6 23,014 0.022 4 2 1.5 % 29.0 %
2025 July 2.65 17,547 0.029 4 17,743 0.019 2 2 -1.1 % 34.5 %
2025 June 12.50 5,481 0.032 1 5,191 0.032 1 0 5.3 % 0.0 %
2025 May 2.04 26,427 0.060 13 22,497 0.051 9 4 14.9 % 15.0 %
2025 April 1.18 9,702 0.057 4 6,142 0.128 6 -2 36.7 % -124.6 %
2025 March 1.53 0 0.012 0 0.164 -1,266.7 %
2025 February 1.65 58 0.024 0 1 0.130 0 0 98.3 % -441.7 %
2025 January 1.19 0 0.022 0 0.145 -559.1 %
Totals 35.77 126,064 0.367 35 117,652 0.748 26 9 13.5 % -178.6 %

Nitrogen, Total

BSTF Pollutant Load Reduction Report for "Nitrogen, Total"
Year / Month Rainfall In (Wet well / Pump A) Out (Wet well / Pump B) Reduction Goal Percent Volume
Lost		 Percent TN
Reduction
SARASOTA_ARMS - AL-1 (in) Volume (kgals) TN conc. (mg/l) TN load (lbs) Volume (kgals) TN conc. (mg/l) TN load (lbs) TN (lbs) TN (lbs)
2025 December 0.34 6,198 3.744 193 5,741 2.419 115 78 278 7.4 % 35.4 %
2025 November 0.06 4,253 2.986 105 5,738 1.970 94 11 278 -34.9 % 34.0 %
2025 October 0.83 18,677 3.107 484 16,603 1.638 226 258 278 11.1 % 47.3 %
2025 September 1.61 14,354 2.003 239 14,982 2.070 258 -19 278 -4.4 % -3.3 %
2025 August 10.19 23,367 2.651 516 23,014 2.102 403 113 278 1.5 % 20.7 %
2025 July 2.65 17,547 3.429 502 17,743 1.949 288 214 278 -1.1 % 43.2 %
2025 June 12.50 5,481 3.762 172 5,191 3.862 167 5 278 5.3 % -2.7 %
2025 May 2.04 26,427 4.880 1,076 22,497 4.341 815 261 278 14.9 % 11.0 %
2025 April 1.18 9,702 5.007 405 6,142 4.608 236 169 278 36.7 % 8.0 %
2025 March 1.53 0 1.362 0 0.849 278 37.7 %
2025 February 1.65 58 4.034 1 1 1.110 0 1 278 98.3 % 72.5 %
2025 January 1.19 0 4.332 0 0.768 278 82.3 %
Totals 35.77 126,064 41.297 3,693 117,652 27.686 2,602 1,091 278 13.5 % 32.2 %

Phosphorus as P

BSTF Pollutant Load Reduction Report for "Phosphorus as P"
Year / Month Rainfall In (Wet well / Pump A) Out (Wet well / Pump B) Reduction Goal Percent Volume
Lost		 Percent TP
Reduction
SARASOTA_ARMS - AL-1 (in) Volume (kgals) TP conc. (mg/l) TP load (lbs) Volume (kgals) TP conc. (mg/l) TP load (lbs) TP (lbs) TP (lbs)
2025 December 0.34 6,198 0.257 13 5,741 0.086 4 9 7.4 % 66.5 %
2025 November 0.06 4,253 0.219 7 5,738 0.116 5 2 -34.9 % 47.0 %
2025 October 0.83 18,677 0.248 38 16,603 0.171 23 15 11.1 % 31.0 %
2025 September 1.61 14,354 0.166 19 14,982 0.184 23 -4 -4.4 % -10.8 %
2025 August 10.19 23,367 0.241 46 23,014 0.177 33 13 1.5 % 26.6 %
2025 July 2.65 17,547 0.239 34 17,743 0.108 15 19 -1.1 % 54.8 %
2025 June 12.50 5,481 0.332 15 5,191 0.331 14 1 5.3 % 0.3 %
2025 May 2.04 26,427 0.395 87 22,497 0.329 61 26 14.9 % 16.7 %
2025 April 1.18 9,702 0.242 19 6,142 0.479 24 -5 36.7 % -97.9 %
2025 March 1.53 0 0.136 0 0.028 79.4 %
2025 February 1.65 58 0.376 0 1 0.036 0 0 98.3 % 90.4 %
2025 January 1.19 0 0.293 0 0.027 90.8 %
Totals 35.77 126,064 3.144 278 117,652 2.072 202 76 13.5 % 32.9 %

Total Suspended Solids (TSS)

BSTF Pollutant Load Reduction Report for "Total Suspended Solids (TSS)"
Year / Month Rainfall In (Wet well / Pump A) Out (Wet well / Pump B) Reduction Goal Percent Volume
Lost		 Percent TSS
Reduction
SARASOTA_ARMS - AL-1 (in) Volume (kgals) TSS conc. (mg/l) TSS load (lbs) Volume (kgals) TSS conc. (mg/l) TSS load (lbs) TSS (lbs) TSS (lbs)
2025 December 0.34 6,198 68.000 3,517 5,741 4.000 191 3,326 7.4 % 94.1 %
2025 November 0.06 4,253 16.000 567 5,738 5.600 268 299 -34.9 % 65.0 %
2025 October 0.83 18,677 60.000 9,352 16,603 4.000 554 8,798 11.1 % 93.3 %
2025 September 1.61 14,354 36.000 4,312 14,982 32.000 4,000 312 -4.4 % 11.1 %
2025 August 10.19 23,367 34.000 6,630 23,014 22.000 4,225 2,405 1.5 % 35.3 %
2025 July 2.65 17,547 48.000 7,028 17,743 10.400 1,539 5,489 -1.1 % 78.3 %
2025 June 12.50 5,481 88.000 4,025 5,191 32.000 1,386 2,639 5.3 % 63.6 %
2025 May 2.04 26,427 145.000 31,978 22,497 68.000 12,766 19,212 14.9 % 53.1 %
2025 April 1.18 9,702 70.000 5,667 6,142 90.000 4,613 1,054 36.7 % -28.6 %
2025 March 1.53 0 35.000 0 0.570 98.4 %
2025 February 1.65 58 108.000 52 1 9.200 0 52 98.3 % 91.5 %
2025 January 1.19 0 56.000 0 2.800 95.0 %
Totals 35.77 126,064 764.000 73,128 117,652 280.570 29,542 43,586 13.5 % 62.5 %