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 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 %
2024 December 0.70 0 5.540 0 2.300 58.5 %
2024 November 0.56 0 2.320 0 1.000 56.9 %
2024 August 19.91 0 1.960 0 1.000 49.0 %
2024 July 7.64 0 2.780 0 1.000 64.0 %
Totals 47.71 41,668 46.430 2,937 33,831 27.590 2,083 854 38.8 % 46.2 %

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 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 %
2024 December 0.70 0 62.100 0 1.900 96.9 %
2024 November 0.56 0 10.600 0 0.440 95.8 %
2024 August 19.91 0 52.300 0 1.250 97.6 %
2024 July 7.64 0 34.300 0 1.510 95.6 %
Totals 47.71 41,668 323.900 10,772 33,831 196.283 31,949 -21,177 38.8 % 28.6 %

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 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 %
2024 December 0.70 0 3.820 0 0.739 80.7 %
2024 November 0.56 0 3.240 0 1.340 58.6 %
2024 August 19.91 0 2.840 0 0.826 70.9 %
2024 July 7.64 0 3.690 0 1.560 57.7 %
Totals 47.71 41,668 32.450 1,634 33,831 18.730 1,199 435 38.8 % 45.6 %

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 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 %
2024 December 0.70 0 0.023 0 0.115 -400.0 %
2024 November 0.56 0 0.026 0 0.117 -350.0 %
2024 August 19.91 0 0.018 0 0.109 -505.6 %
2024 July 7.64 0 0.019 0 0.159 -736.8 %
Totals 47.71 41,668 0.271 18 33,831 1.005 16 2 38.8 % -423.4 %

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 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 %
2024 December 0.70 0 3.843 0 0.854 278 77.8 %
2024 August 19.91 0 2.858 0 0.935 278 67.3 %
2024 July 7.64 0 3.709 0 1.719 278 53.7 %
Totals 47.15 41,668 29.455 1,654 33,831 18.278 1,218 436 278 38.8 % 40.7 %

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 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 %
2024 December 0.70 0 0.335 0 0.037 89.0 %
2024 November 0.56 0 0.279 0 0.054 80.6 %
2024 August 19.91 0 0.268 0 0.072 73.1 %
2024 July 7.64 0 0.199 0 0.035 82.4 %
Totals 47.71 41,668 2.562 121 33,831 1.401 99 22 38.8 % 46.0 %

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 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 %
2024 December 0.70 0 36.000 0 0.800 97.8 %
2024 November 0.56 0 16.000 0 3.000 81.3 %
2024 August 19.91 0 16.000 0 0.570 96.4 %
2024 July 7.64 0 26.700 0 3.200 88.0 %
Totals 47.71 41,668 540.700 41,722 33,831 207.340 18,765 22,957 38.8 % 71.3 %