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Roberts Bay Condition Report for 2016

View 2015 Report

Caution

1 out of 3 indicators were rated as PASS.

All three indicators must pass
for the bay to be rated as PASS.

Learn more about how this report is created

Summary:

The overall health of Roberts Bay degraded in 2016 with all three water quality indicators showing an increase compared to 2015. The increases caused it to exceed the threshold level for chlorophyll a and nitrogen. Phosphorus concentration increased somewhat but is still well below the target value of 0.23 mg/l.

Water Quality: The increases to chlorophyll a and nitrogen earned the rating of "Caution". Mean nitrogen concentration was 0.554 mg/l and mean chlorophyll a concentration was 0.0117 mg/l. Both of these mean concentrations exceeded threshold values (0.54 mg/l for nitrogen and 0.011 mg/l for chlorophyll a). The mean for chlorophyll a a was calculated as an arithmetic mean and the means for nitrogen and phosphorus were calculated as geometric means (per the Numeric Nutrient Criteria outlined in the Florida Administrative Code, section 62-302.532). Phosphorus concentrations increased slightly to 0.1194 mg/l, however this concentration remains below the target value of 0.19 mg/l and the threshold of 0.23 mg/l earning an "Excellent" rating.

Biotic Indicator: Measurement of the biotic indicator, seagrass, was performed in 2016 by the Southwest Florida Water Management District. Total seagrass acreage in Roberts Bay increased slightly to 356 acres from its previous value exceeding the desired target of 348 acres.

Water Chemistry Ratings

Total nitrogen, total phosphorus, and chlorophyll a levels are monitored carefully by water resource managers and used by regulatory authorities to determine whether a bay meets the water quality standards mandated by the Clean Water Act. The trend graphs for these indicators are shown below, along with their target and threshold values. A target value is a desirable goal to be attained, while a threshold is an undesirable level which is to be avoided. Learn More about these ratings and how they are calculated »

The Five-year Trend Graphs below illustrate the general trend of water quality parameters. They show a six-month running average, which moderates high and low values in the data.

Caution

Chlorophyll a

Score: Caution How was this determined?
Units: mg/l Year
2016
Historical
period of record
High 0.0514 0.0514
Mean 0.0117 0.0082 0.00774309 0.0082000000
Low 0.002 0.0003
No. of Samples 66 1,205

Five-year Trend Graph

     
1/1/20124.4250.0044200mg/l
2/1/20128.9050.0066600mg/l
3/1/20126.5950.0066400mg/l
4/1/20124.8650.0061900mg/l
5/1/20125.4150.0060400mg/l
6/1/20126.5550.0061200mg/l
7/1/20129.9550.0070400mg/l
8/1/201215.4050.0081300mg/l
9/1/201216.2450.0097400mg/l
10/1/20129.5150.0105100mg/l
11/1/20123.5260.0102000mg/l
12/1/20124.2860.0098200mg/l
1/1/20133.1050.0086800mg/l
2/1/20133.5050.0066900mg/l
3/1/20133.8550.0046300mg/l
4/1/20135.6450.0039800mg/l
5/1/20135.1950.0042600mg/l
6/1/20137.5350.0048000mg/l
7/1/201320.6950.0077300mg/l
8/1/201315.7450.0097700mg/l
9/1/201318.7050.0122500mg/l
10/1/201325.5450.0155700mg/l
11/1/20139.1750.0162300mg/l
12/1/20132.8650.0154500mg/l
1/1/20143.7150.0126200mg/l
2/1/20142.2950.0103800mg/l
3/1/20143.9150.0079100mg/l
4/1/20143.9250.0043100mg/l
5/1/201410.9250.0046000mg/l
6/1/20144.4950.0048700mg/l
7/1/20148.1850.0056200mg/l
8/1/20144.4250.0059700mg/l
9/1/20149.0560.0068300mg/l
10/1/201418.1260.0092000mg/l
11/1/20145.7360.0083300mg/l
12/1/20143.5050.0081700mg/l
1/1/201519.8050.0101000mg/l
2/1/20152.2360.0097400mg/l
3/1/20154.2850.0089400mg/l
4/1/20153.4860.0065000mg/l
5/1/20153.8550.0061900mg/l
6/1/20157.7360.0069000mg/l
7/1/201510.0750.0052700mg/l
8/1/201519.5460.0081600mg/l
9/1/201521.4450.0110200mg/l
10/1/201517.4360.0133400mg/l
11/1/201511.5050.0146200mg/l
12/1/201515.2860.0158800mg/l
1/1/20164.8650.0150100mg/l
2/1/20166.8560.0128900mg/l
3/1/20164.0750.0100000mg/l
4/1/20165.4160.0080000mg/l
5/1/20165.1650.0069400mg/l
6/1/20169.7760.0060200mg/l
7/1/20169.3650.0067700mg/l
8/1/201613.5160.0078800mg/l
9/1/201637.2850.0134200mg/l
10/1/201626.6860.0169600mg/l
11/1/201612.5050.0181800mg/l
12/1/20165.5860.0174900mg/l
Loading Chart...
Target
0.0082 mg/l
Threshold
0.011 mg/l
Caution

Nitrogen, Total

Score: Caution How was this determined?
Units: mg/l Year
2016
Historical
period of record
High 1.198 1.376
Mean 0.554 0.4331 0.17575058 0.4500000000
Low 0.315 0.065
No. of Samples 66 1,197

Five-year Trend Graph

     
1/1/2012349.6050.3496000mg/l
2/1/2012466.0050.4078000mg/l
3/1/2012523.0050.4462000mg/l
4/1/2012417.0050.4389000mg/l
5/1/2012349.0050.4209200mg/l
6/1/2012295.0050.3999300mg/l
7/1/2012588.0050.4396700mg/l
8/1/2012571.6050.4572700mg/l
9/1/2012601.0050.4702700mg/l
10/1/2012533.6050.4897000mg/l
11/1/2012413.6760.5004800mg/l
12/1/2012385.6760.5155900mg/l
1/1/2013358.4050.4773200mg/l
2/1/2013343.0050.4392200mg/l
3/1/2013279.4050.3856200mg/l
4/1/2013399.0050.3631900mg/l
5/1/2013417.0050.3637500mg/l
6/1/2013516.6050.3855700mg/l
7/1/2013779.0050.4556700mg/l
8/1/2013780.6050.5286000mg/l
9/1/2013845.6050.6229700mg/l
10/1/2013823.6050.6937300mg/l
11/1/2013557.0050.7170700mg/l
12/1/2013512.4050.7163700mg/l
1/1/2014417.8050.6561700mg/l
2/1/2014456.6050.6021700mg/l
3/1/2014453.2050.5367700mg/l
4/1/2014486.2050.4805300mg/l
5/1/2014537.2050.4772300mg/l
6/1/2014520.2050.4785300mg/l
7/1/2014537.2050.4984300mg/l
8/1/2014569.4050.5172300mg/l
9/1/2014658.5060.5514500mg/l
10/1/2014656.6760.5798600mg/l
11/1/2014475.0060.5695000mg/l
12/1/2014518.6050.5692300mg/l
1/1/2015589.0050.5778600mg/l
2/1/2015338.8360.5394300mg/l
3/1/2015413.0050.4985200mg/l
4/1/2015260.1760.4324300mg/l
5/1/2015407.0050.4211000mg/l
6/1/2015528.3360.4227200mg/l
7/1/2015565.0050.4187200mg/l
8/1/2015745.3360.4864700mg/l
9/1/2015739.6050.5409100mg/l
10/1/2015566.3360.5919300mg/l
11/1/2015570.8050.6192300mg/l
12/1/2015509.8360.6161500mg/l
1/1/2016675.8050.6346200mg/l
2/1/2016467.0060.5882300mg/l
3/1/2016446.0050.5392900mg/l
4/1/2016497.3360.5277900mg/l
5/1/2016405.2050.5001900mg/l
6/1/2016594.3360.5142800mg/l
7/1/2016375.4050.4642100mg/l
8/1/2016582.1760.4834100mg/l
9/1/2016977.6050.5720100mg/l
10/1/2016954.0060.6481200mg/l
11/1/2016482.6050.6610200mg/l
12/1/2016523.0060.6491300mg/l
Loading Chart...
Target
0.45 mg/l
Threshold
0.54 mg/l
Excellent

Phosphorus, Total

Score: Excellent How was this determined?
Units: mg/l Year
2016
Historical
period of record
High 0.30 0.48
Mean 0.1194 0.1335 0.06606589 0.1900000000
Low 0.05 0.05
No. of Samples 66 1,206

Five-year Trend Graph

     
1/1/201256.0050.0560000mg/l
2/1/201276.0050.0660000mg/l
3/1/201288.0050.0733300mg/l
4/1/201282.0050.0755000mg/l
5/1/201268.0050.0740000mg/l
6/1/201268.0050.0730000mg/l
7/1/2012174.0050.0926700mg/l
8/1/2012144.0050.1040000mg/l
9/1/2012134.0050.1116700mg/l
10/1/201288.0050.1126700mg/l
11/1/201280.0060.1146700mg/l
12/1/201293.3360.1188900mg/l
1/1/201364.0050.1005600mg/l
2/1/201352.0050.0852200mg/l
3/1/2013118.0050.0825600mg/l
4/1/201392.0050.0832200mg/l
5/1/201356.0050.0792200mg/l
6/1/2013104.0050.0810000mg/l
7/1/2013166.0050.0980000mg/l
8/1/2013150.0050.1143300mg/l
9/1/2013148.0050.1193300mg/l
10/1/2013162.0050.1310000mg/l
11/1/2013112.0050.1403300mg/l
12/1/201378.0050.1360000mg/l
1/1/201458.0050.1180000mg/l
2/1/201466.0050.1040000mg/l
3/1/201486.0050.0936700mg/l
4/1/2014106.0050.0843300mg/l
5/1/2014126.0050.0866700mg/l
6/1/2014120.0050.0936700mg/l
7/1/2014150.0050.1090000mg/l
8/1/2014138.0050.1210000mg/l
9/1/2014110.0060.1250000mg/l
10/1/201495.0060.1231700mg/l
11/1/201493.3360.1177200mg/l
12/1/201458.0050.1073900mg/l
1/1/201592.0050.0977200mg/l
2/1/201573.3360.0869400mg/l
3/1/201560.0050.0786100mg/l
4/1/2015113.3360.0816700mg/l
5/1/201570.0050.0777800mg/l
6/1/201586.6760.0825600mg/l
7/1/2015140.0050.0905600mg/l
8/1/2015170.0060.1066700mg/l
9/1/2015138.0050.1196700mg/l
10/1/2015123.3360.1213300mg/l
11/1/2015128.0050.1310000mg/l
12/1/2015101.6760.1335000mg/l
1/1/2016146.0050.1345000mg/l
2/1/201676.6760.1189500mg/l
3/1/201692.0050.1112800mg/l
4/1/201683.3360.1046100mg/l
5/1/2016112.0050.1019500mg/l
6/1/2016148.3360.1097200mg/l
7/1/201692.0050.1007200mg/l
8/1/201698.3360.1043300mg/l
9/1/2016232.0050.1276700mg/l
10/1/2016255.0060.1562800mg/l
11/1/2016128.0050.1589400mg/l
12/1/2016128.3360.1556100mg/l
Loading Chart...
Target
0.19 mg/l
Threshold
0.23 mg/l

Dissolved Oxygen

Units: mg/l Year
2016
Historical
period of record
High 11.60 11.60
Mean 6.54 6.48 1.18108
Low 4.20 3.50
No. of Samples 60 1,330

Five-year Trend Graph

     
1/1/20127.6457.6400000mg/l
2/1/20126.8257.2300000mg/l
3/1/20127.1657.2100000mg/l
4/1/20126.2656.9700000mg/l
5/1/20126.4256.8600000mg/l
6/1/20125.6856.6600000mg/l
7/1/20125.6056.3200000mg/l
8/1/20125.5456.1100000mg/l
9/1/20126.2855.9600000mg/l
10/1/20125.8055.8900000mg/l
11/1/20125.4655.7300000mg/l
12/1/20126.1455.8000000mg/l
1/1/20136.0655.8800000mg/l
2/1/20137.8256.2600000mg/l
3/1/20136.8256.3500000mg/l
4/1/20136.9456.5400000mg/l
5/1/20136.1456.6500000mg/l
6/1/20135.1656.4900000mg/l
7/1/20137.7856.7800000mg/l
8/1/20134.9856.3000000mg/l
9/1/20136.9256.3200000mg/l
10/1/20136.4056.2300000mg/l
11/1/20136.8856.3500000mg/l
12/1/20136.7056.6100000mg/l
1/1/20147.5256.5700000mg/l
2/1/20147.4256.9700000mg/l
3/1/20146.3856.8800000mg/l
4/1/20146.7256.9400000mg/l
5/1/20147.6657.0700000mg/l
6/1/20145.5256.8700000mg/l
7/1/20144.8256.4200000mg/l
8/1/20143.9855.8500000mg/l
9/1/20145.2055.6500000mg/l
10/1/20147.8655.8400000mg/l
11/1/20147.4055.8000000mg/l
12/1/20146.1855.9100000mg/l
1/1/20157.7856.4000000mg/l
2/1/20158.0857.0800000mg/l
3/1/20156.9457.3700000mg/l
4/1/20157.4457.3000000mg/l
5/1/20156.3257.1200000mg/l
6/1/20156.6657.2000000mg/l
7/1/20155.4456.8100000mg/l
8/1/20158.3856.8600000mg/l
9/1/20156.8856.8500000mg/l
10/1/20155.9456.6000000mg/l
11/1/20155.4056.4500000mg/l
12/1/20156.3856.4000000mg/l
1/1/20167.1656.6900000mg/l
2/1/20167.8856.6100000mg/l
3/1/20166.6256.5600000mg/l
4/1/20166.7856.7000000mg/l
5/1/20166.8256.9400000mg/l
6/1/20165.4456.7800000mg/l
7/1/20165.6656.5300000mg/l
8/1/20166.3856.2800000mg/l
9/1/20168.8256.6500000mg/l
10/1/20165.6856.4700000mg/l
11/1/20166.0856.3400000mg/l
12/1/20165.1856.3000000mg/l
Loading Chart...
Target
mg/l
Threshold
0.00 mg/l

Light Attenuation

Units: K(1/m) Year
2016
Historical
period of record
High 2.20 3.56
Mean 1.09 1.02 0.42651
Low 0.38 0.19
No. of Samples 59 1,128

Five-year Trend Graph

     
1/1/20120.9450.9400000K(1/m)
2/1/20121.1751.0600000K(1/m)
3/1/20120.9651.0200000K(1/m)
4/1/20120.9851.0100000K(1/m)
5/1/20120.6550.9400000K(1/m)
6/1/20120.7850.9100000K(1/m)
7/1/20121.3050.9700000K(1/m)
8/1/20121.1850.9800000K(1/m)
9/1/20121.5251.0700000K(1/m)
10/1/20121.3551.1300000K(1/m)
11/1/20120.7451.1500000K(1/m)
12/1/20120.5451.1100000K(1/m)
1/1/20130.8351.0300000K(1/m)
2/1/20130.8350.9700000K(1/m)
3/1/20130.8950.8600000K(1/m)
4/1/20130.8650.7800000K(1/m)
5/1/20130.8550.8000000K(1/m)
6/1/20130.7850.8400000K(1/m)
7/1/20131.5850.9700000K(1/m)
8/1/20131.2551.0400000K(1/m)
9/1/20131.4951.1400000K(1/m)
10/1/20131.8951.3100000K(1/m)
11/1/20130.9651.3300000K(1/m)
12/1/20130.7651.3200000K(1/m)
1/1/20140.5451.1500000K(1/m)
2/1/20140.9951.1100000K(1/m)
3/1/20140.8250.9900000K(1/m)
4/1/20140.9050.8300000K(1/m)
5/1/20141.0450.8400000K(1/m)
6/1/20140.8350.8500000K(1/m)
7/1/20140.8250.9000000K(1/m)
8/1/20140.9150.8900000K(1/m)
9/1/20141.0150.9200000K(1/m)
10/1/20141.7251.0600000K(1/m)
11/1/20140.7751.0100000K(1/m)
12/1/20140.9751.0300000K(1/m)
1/1/20151.1051.0800000K(1/m)
2/1/20150.8351.0700000K(1/m)
3/1/20150.7651.0300000K(1/m)
4/1/20150.7750.8700000K(1/m)
5/1/20150.6250.8400000K(1/m)
6/1/20150.8350.8200000K(1/m)
7/1/20150.8650.7800000K(1/m)
8/1/20151.4950.8900000K(1/m)
9/1/20151.4651.0100000K(1/m)
10/1/20151.2251.0800000K(1/m)
11/1/20151.0251.1500000K(1/m)
12/1/20151.0951.1900000K(1/m)
1/1/20160.5851.1400000K(1/m)
2/1/20161.2451.1000000K(1/m)
3/1/20160.8951.0100000K(1/m)
4/1/20160.9650.9600000K(1/m)
5/1/20160.6350.9000000K(1/m)
6/1/20160.9750.8800000K(1/m)
7/1/20160.7550.9100000K(1/m)
8/1/20161.2050.9000000K(1/m)
9/1/20162.0251.0900000K(1/m)
10/1/20161.5451.1900000K(1/m)
11/1/20161.3641.3100000K(1/m)
12/1/20161.0451.3200000K(1/m)
Loading Chart...
Target
K(1/m)
Threshold
0.00 K(1/m)

Rainfall

Units: inches/yr Year
2016
Historical
period of record
High 43.06 54.47
Mean 35.43 10.8481834454407
Low 14.17
No. of Samples 366 4,803

Five-year Trend Graph

     
1/1/20120.67290.6700000inches
2/1/20121.05291.0500000inches
3/1/20121.67311.6700000inches
4/1/20122.57242.5700000inches
5/1/20121.86311.8600000inches
6/1/201215.043015.0400000inches
7/1/20124.59314.5900000inches
8/1/20128.33318.3300000inches
9/1/20122.20302.2000000inches
10/1/20122.49312.4900000inches
11/1/20120.00280.0000000inches
12/1/20121.59311.5900000inches
1/1/20130.17310.1700000inches
2/1/20131.06231.0600000inches
3/1/20130.81300.8100000inches
4/1/20133.43303.4300000inches
5/1/20132.93312.9300000inches
6/1/20137.39307.3900000inches
7/1/201311.003111.0000000inches
8/1/201310.603110.6000000inches
9/1/201315.013015.0100000inches
10/1/20130.96310.9600000inches
11/1/20130.91300.9100000inches
12/1/20130.20310.2000000inches
1/1/20142.55312.5500000inches
2/1/20142.36282.3600000inches
3/1/20145.96315.9600000inches
4/1/20140.97290.9700000inches
5/1/20145.40315.4000000inches
6/1/20143.66303.6600000inches
7/1/20142.01312.0100000inches
8/1/20143.71283.7100000inches
9/1/20148.19268.1900000inches
10/1/20142.22302.2200000inches
11/1/20144.09304.0900000inches
12/1/20140.50310.5000000inches
1/1/20150.78310.7800000inches
2/1/20153.64283.6400000inches
3/1/20150.97310.9700000inches
4/1/20151.50301.5000000inches
5/1/20152.94312.9400000inches
6/1/20152.73302.7300000inches
7/1/20155.90315.9000000inches
8/1/20155.31315.3100000inches
9/1/20156.17306.1700000inches
10/1/20151.48311.4800000inches
11/1/20150.73300.7300000inches
12/1/20152.18312.1800000inches
1/1/20164.07314.0700000inches
2/1/20161.27291.2700000inches
3/1/20161.69311.6900000inches
4/1/20160.62300.6200000inches
5/1/20164.22314.2200000inches
6/1/20165.87305.8700000inches
7/1/20164.64314.6400000inches
8/1/201613.003113.0000000inches
9/1/20164.46304.4600000inches
10/1/20162.61312.6100000inches
11/1/20160.01300.0100000inches
12/1/20160.60310.6000000inches
Loading Chart...
Target
inches/yr
Threshold
inches/yr

Salinity

Units: PSS Year
2016
Historical
period of record
High 33.50 38.80
Mean 27.0 30.43 5.06433
Low 6.00 1.80
No. of Samples 60 1,330

Five-year Trend Graph

     
1/1/201232.82532.8200000PSS
2/1/201232.84532.8300000PSS
3/1/201234.80533.4900000PSS
4/1/201236.38534.2100000PSS
5/1/201235.70534.5100000PSS
6/1/201233.76534.3800000PSS
7/1/201226.04533.2500000PSS
8/1/201227.44532.3500000PSS
9/1/201229.02531.3900000PSS
10/1/201229.00530.1600000PSS
11/1/201233.22529.7500000PSS
12/1/201232.96529.6100000PSS
1/1/201332.48530.6900000PSS
2/1/201332.94531.6000000PSS
3/1/201333.26532.3100000PSS
4/1/201332.00532.8100000PSS
5/1/201333.94532.9300000PSS
6/1/201334.14533.1300000PSS
7/1/201322.86531.5200000PSS
8/1/201324.12530.0500000PSS
9/1/201318.70527.6300000PSS
10/1/201324.02526.3000000PSS
11/1/201329.56525.5700000PSS
12/1/201331.16525.0700000PSS
1/1/201432.24526.6300000PSS
2/1/201431.30527.8300000PSS
3/1/201432.20530.0800000PSS
4/1/201429.02530.9100000PSS
5/1/201426.14530.3400000PSS
6/1/201432.32530.5400000PSS
7/1/201431.38530.3900000PSS
8/1/201432.72530.6300000PSS
9/1/201431.46530.5100000PSS
10/1/201423.60529.6000000PSS
11/1/201432.64530.6900000PSS
12/1/201429.12530.1500000PSS
1/1/201530.40529.9900000PSS
2/1/201530.76529.6600000PSS
3/1/201529.56529.3500000PSS
4/1/201532.38530.8100000PSS
5/1/201534.26531.0800000PSS
6/1/201532.32531.6100000PSS
7/1/201534.20532.2500000PSS
8/1/201519.84530.4300000PSS
9/1/201522.54529.2600000PSS
10/1/201526.02528.2000000PSS
11/1/201529.70527.4400000PSS
12/1/201531.58527.3100000PSS
1/1/201630.82526.7500000PSS
2/1/201627.00527.9400000PSS
3/1/201630.70529.3000000PSS
4/1/201630.90530.1200000PSS
5/1/201630.52530.2500000PSS
6/1/201626.96529.4800000PSS
7/1/201631.82529.6500000PSS
8/1/201625.40529.3800000PSS
9/1/201614.86526.7400000PSS
10/1/201613.92523.9100000PSS
11/1/201629.56523.7500000PSS
12/1/201631.54524.5200000PSS
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Turbidity

Units: NTU Year
2016
Historical
period of record
High 10.00 24.00
Mean 4.25 4.26 2.09306
Low 1.70 0.85
No. of Samples 66 1,206

Five-year Trend Graph

     
1/1/20124.1654.1600000NTU
2/1/20127.3055.7300000NTU
3/1/20127.1856.2100000NTU
4/1/20129.1656.9500000NTU
5/1/20126.5256.8600000NTU
6/1/20124.5456.4800000NTU
7/1/20125.8056.7500000NTU
8/1/20125.4856.4500000NTU
9/1/20127.4056.4800000NTU
10/1/20125.8055.9200000NTU
11/1/20122.8565.3100000NTU
12/1/20122.3564.9500000NTU
1/1/20132.7054.4300000NTU
2/1/20134.1854.2100000NTU
3/1/20136.1454.0000000NTU
4/1/20135.3253.9200000NTU
5/1/20135.8454.4200000NTU
6/1/20133.0054.5300000NTU
7/1/20136.6055.1800000NTU
8/1/20134.3855.2100000NTU
9/1/20136.8855.3400000NTU
10/1/20135.8855.4300000NTU
11/1/20135.1655.3200000NTU
12/1/20132.0855.1600000NTU
1/1/20142.0854.4100000NTU
2/1/20141.9454.0000000NTU
3/1/20142.7053.3100000NTU
4/1/20143.6452.9300000NTU
5/1/20143.1652.6000000NTU
6/1/20142.6452.6900000NTU
7/1/20145.4053.2500000NTU
8/1/20144.7653.7200000NTU
9/1/20144.0063.9300000NTU
10/1/20145.1864.1900000NTU
11/1/20142.7564.1200000NTU
12/1/20143.0054.1800000NTU
1/1/20155.0454.1200000NTU
2/1/20152.8863.8100000NTU
3/1/20153.1853.6700000NTU
4/1/20153.2363.3500000NTU
5/1/20153.3253.4400000NTU
6/1/20153.4063.5100000NTU
7/1/20155.7853.6300000NTU
8/1/20156.3764.2100000NTU
9/1/20155.0054.5200000NTU
10/1/20155.3564.8700000NTU
11/1/20154.4055.0500000NTU
12/1/20153.8065.1200000NTU
1/1/20162.3854.5500000NTU
2/1/20163.6764.1000000NTU
3/1/20164.6654.0400000NTU
4/1/20165.6564.0900000NTU
5/1/20162.7453.8200000NTU
6/1/20163.3763.7500000NTU
7/1/20163.7053.9700000NTU
8/1/20164.0864.0300000NTU
9/1/20165.6054.1900000NTU
10/1/20165.6264.1900000NTU
11/1/20165.7654.6900000NTU
12/1/20163.6764.7400000NTU
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Other Measures of Bay Health

In addition to nutrient levels and chlorophyll concentration, dissolved oxygen levels, and water clarity are also objective indicators of bay health. These have complex interactive cycles which are affected by rainfall, temperature, and tidal action, as well as other factors. High nutrient levels (nitrogen and phosphorus) can stimulate excessive growth of marine algae (indicated by chlorophyll a level), resulting in reduced water clarity (and increased light attenuation) and depleted oxygen levels. Both plants and animals in a bay need oxygen to survive, and the seagrasses which provide food and cover for bay creatures need light for photosynthesis.

Bay Contour Maps (2016)

Contour mapping is one of the best ways to visualize spatial differences in coastal water quality. The interactive map shown below presents monthly data for one selected water quality indicator atop an aerial view of the bay. Choose a different water quality parameter from the list at the top to change the map. Learn More about Water Quality Contour Mapping »

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Contour Visibility:

Visit the Water Quality Contour Mapping Tool to view and compare monthly water quality contour maps for ten different water quality indicators. In addition, you can generate your own custom maps.

Contour Legend:

  • Less than 1 mg/l
  • 1.0 - 5.9 mg/l
  • 6.0 - 10.9 mg/l
  • 11.0 - 17.9 mg/l
  • Greater than 18 mg/l

Seagrasses

Among the most important habitats in Florida's estuarine environments, seagrass beds are indispensable for the role they play in cycling nutrients, supplying food for wildlife, stabilizing sediments, and providing habitat for juvenile and adult finfish and shellfish. Use the interactive map below to observe the size, density and location of seagrass beds from year to year. The graph shows how the total amount of seagrass in the bay has changed over time. Learn More about Seagrasses »

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Target
348 acres

Land Use / Land Cover

Land use within a bay's watershed has a major effect on its water quality. In general, less development means better water quality. Land Cover/Land Use classifications categorize land in terms of its observed physical surface characteristics (upland or wetland, e.g.), and also reflect the types of activity that are taking place on it (agriculture, urban/built-up, utilities, etc.). Florida uses as its standard a set of statewide classifications which were developed by the Florida Department of Transportation. Learn More about Land Use and Land Cover »

Roberts Bay is located within the Sarasota Bay Watershed. The chart below shows the land use / land cover characteristics for Sarasota Bay Watershed within the boundary of this Water Atlas. View details about the Sarasota Bay Watershed »

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