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Dona/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 Dona/Roberts Bay continued to deteriorate in 2016. Chlorophyll a increased significantly to a mean concentration of 0.0094 mg/l, above the threshold concentration of 0.0049 mg/l. Nitrogen concentration also increased, reaching  the “Caution” range, exceeding target and threshold levels. The mean value for phosphorus concentration increased but is still well below the target.

Water Quality: All three nutrient measures used in scoring water quality increased in 2016, a worsening trend. The mean chlorophyll a concentration in 2016 was 0.0094 mg/l, exceeding the threshold value of 0.0049 mg/l. Mean nitrogen concentration was 0.5533 mg/l, higher than the threshold of 0.420 mg/l. The annual mean concentration of phosphorus, although higher than in 2016, remained well below the threshold of 0.180 mg/l, at 0.1022 mg/l. The mean for chlorophyll 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). In 2016, Dona/Roberts Bay retains its "Caution" rating, with two out of three water quality measures exceeding threshold values.

Biotic Indicator: Measurement of the biotic indicator, seagrass, was performed in 2016 by the Southwest Florida Water Management District. The increase in total seagrass acreage in Dona/Roberts Bay was slight. Between 2014 and 2016 it increased from 99 to 101 acres, remaining below the target level of 112 acres.

Bay Location Map

Bays included in this report:

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 0.0588 0.0612
Mean 0.0094 0.0055 0.0064483 0.0043000000
Low 0.002 0.0001
No. of Samples 49 690

Five-year Trend Graph

     
1/1/20122.0340.0020300mg/l
2/1/20122.0340.0020300mg/l
3/1/20122.0440.0020300mg/l
4/1/20121.1840.0018200mg/l
5/1/20123.1240.0020800mg/l
6/1/20125.4940.0026500mg/l
7/1/20127.3940.0035400mg/l
8/1/20128.5140.0046200mg/l
9/1/20125.2250.0051500mg/l
10/1/20125.1040.0058100mg/l
11/1/20124.1150.0059700mg/l
12/1/20121.8340.0053600mg/l
1/1/20136.0440.0051400mg/l
2/1/20131.8240.0040200mg/l
3/1/20132.3440.0035400mg/l
4/1/20131.9840.0030200mg/l
5/1/20132.5940.0027700mg/l
6/1/201310.6540.0042400mg/l
7/1/201311.0940.0050800mg/l
8/1/20138.6340.0062100mg/l
9/1/20136.9140.0069800mg/l
10/1/201318.9840.0098100mg/l
11/1/20133.9540.0100400mg/l
12/1/20134.0440.0089300mg/l
1/1/20143.1940.0076200mg/l
2/1/20142.0840.0065300mg/l
3/1/20142.1640.0057300mg/l
4/1/20142.3340.0029600mg/l
5/1/20145.3140.0031900mg/l
6/1/20147.4140.0037500mg/l
7/1/20146.9940.0043800mg/l
8/1/20144.5140.0047900mg/l
9/1/20145.6740.0053700mg/l
10/1/201415.3140.0075300mg/l
11/1/20144.6140.0074200mg/l
12/1/20145.7240.0071400mg/l
1/1/20153.5350.0065600mg/l
2/1/20153.4440.0063800mg/l
3/1/20152.7840.0059000mg/l
4/1/20152.2340.0037200mg/l
5/1/20152.9540.0034400mg/l
6/1/20158.7640.0039500mg/l
7/1/20156.0540.0043700mg/l
8/1/201512.2540.0058400mg/l
9/1/201512.7740.0075000mg/l
10/1/201517.0540.0099700mg/l
11/1/20159.7950.0111100mg/l
12/1/20155.2640.0105300mg/l
1/1/20163.0440.0100300mg/l
2/1/20169.1940.0095200mg/l
3/1/20163.5640.0079800mg/l
4/1/20163.5540.0057300mg/l
5/1/20165.2740.0049800mg/l
6/1/201617.3740.0070000mg/l
7/1/20166.9140.0076400mg/l
8/1/20166.3640.0071700mg/l
9/1/201611.2440.0084500mg/l
10/1/201636.4540.0139300mg/l
11/1/20163.8940.0137000mg/l
12/1/20166.2450.0118500mg/l
Loading Chart...
Target
0.0043 mg/l
Threshold
0.0049 mg/l
Caution

Nitrogen, Total

Score: Caution How was this determined?
Units: mg/l Year
2016
Historical
period of record
High 1.31 1.715
Mean 0.5533 0.4472 0.27604783 0.4000000000
Low 0.165 0.055
No. of Samples 49 686

Five-year Trend Graph

     
1/1/2012275.5040.2755000mg/l
2/1/2012349.0040.3122500mg/l
3/1/2012337.5040.3206700mg/l
4/1/2012270.0040.3080000mg/l
5/1/2012260.0040.2984000mg/l
6/1/2012267.5040.2932500mg/l
7/1/2012809.0040.3821700mg/l
8/1/2012543.0040.4145000mg/l
9/1/2012727.4050.4794800mg/l
10/1/2012503.0040.5183200mg/l
11/1/2012494.6050.5574200mg/l
12/1/2012240.0040.5528300mg/l
1/1/2013351.5040.4765800mg/l
2/1/2013258.0040.4290800mg/l
3/1/2013175.0040.3370200mg/l
4/1/2013275.2540.2990600mg/l
5/1/2013397.5040.2828800mg/l
6/1/2013615.2540.3454200mg/l
7/1/20131016.2540.4562100mg/l
8/1/2013850.2540.5549200mg/l
9/1/2013770.7540.6542100mg/l
10/1/2013987.5040.7729200mg/l
11/1/2013418.2540.7763800mg/l
12/1/2013401.0040.7406700mg/l
1/1/2014353.5040.6302100mg/l
2/1/2014396.2540.5545400mg/l
3/1/2014365.2540.4869600mg/l
4/1/2014420.2540.3924200mg/l
5/1/2014425.2540.3935800mg/l
6/1/2014530.0040.4150800mg/l
7/1/2014470.7540.4346300mg/l
8/1/2014758.0040.4949200mg/l
9/1/2014614.2540.5364200mg/l
10/1/20141019.5040.6362900mg/l
11/1/2014462.7540.6425400mg/l
12/1/2014473.5040.6331300mg/l
1/1/2015504.0050.6386700mg/l
2/1/2015315.5040.5649200mg/l
3/1/2015340.0040.5192100mg/l
4/1/2015180.0040.3792900mg/l
5/1/2015372.7540.3642900mg/l
6/1/2015535.0040.3745400mg/l
7/1/2015414.0040.3595400mg/l
8/1/2015995.2540.4728300mg/l
9/1/2015950.7540.5746300mg/l
10/1/2015797.0040.6774600mg/l
11/1/2015814.6050.7511000mg/l
12/1/2015339.7540.7185600mg/l
1/1/2016383.7540.7135200mg/l
2/1/2016731.2540.6695200mg/l
3/1/2016480.2540.5911000mg/l
4/1/2016407.5040.5261800mg/l
5/1/2016382.5040.4541700mg/l
6/1/2016622.7540.5013300mg/l
7/1/2016318.5040.4904600mg/l
8/1/2016708.5040.4866700mg/l
9/1/20161031.0040.5784600mg/l
10/1/2016910.2540.6622500mg/l
11/1/2016283.5040.6457500mg/l
12/1/2016414.8050.6110900mg/l
Loading Chart...
Target
0.40 mg/l
Threshold
0.42 mg/l
Excellent

Phosphorus, Total

Score: Excellent How was this determined?
Units: mg/l Year
2016
Historical
period of record
High 0.29 0.47
Mean 0.1022 0.1224 0.07203209 0.1700000000
Low 0.05 0.05
No. of Samples 49 690

Five-year Trend Graph

     
1/1/201250.0040.0500000mg/l
2/1/201260.0040.0550000mg/l
3/1/201255.0040.0550000mg/l
4/1/201250.0040.0537500mg/l
5/1/201265.0040.0560000mg/l
6/1/201260.0040.0566700mg/l
7/1/2012242.5040.0887500mg/l
8/1/2012112.5040.0975000mg/l
9/1/2012126.0050.1093300mg/l
10/1/201287.5040.1155800mg/l
11/1/201296.0050.1207500mg/l
12/1/201250.0040.1190800mg/l
1/1/201357.5040.0882500mg/l
2/1/201350.0040.0778300mg/l
3/1/201365.0040.0676700mg/l
4/1/201355.0040.0622500mg/l
5/1/201350.0040.0545800mg/l
6/1/2013125.0040.0670800mg/l
7/1/2013237.5040.0970800mg/l
8/1/2013160.0040.1154200mg/l
9/1/201397.5040.1208300mg/l
10/1/2013195.0040.1441700mg/l
11/1/201370.0040.1475000mg/l
12/1/201352.5040.1354200mg/l
1/1/201457.5040.1054200mg/l
2/1/201465.0040.0895800mg/l
3/1/201457.5040.0829200mg/l
4/1/201487.5040.0650000mg/l
5/1/201485.0040.0675000mg/l
6/1/2014115.0040.0779200mg/l
7/1/2014130.0040.0900000mg/l
8/1/2014137.5040.1020800mg/l
9/1/201475.0040.1050000mg/l
10/1/2014170.0040.1187500mg/l
11/1/201485.0040.1187500mg/l
12/1/201450.0040.1079200mg/l
1/1/201578.0050.0992500mg/l
2/1/201575.0040.0888300mg/l
3/1/201550.0040.0846700mg/l
4/1/201580.0040.0696700mg/l
5/1/201565.0040.0663300mg/l
6/1/2015107.5040.0759200mg/l
7/1/2015100.0040.0795800mg/l
8/1/2015195.0040.0995800mg/l
9/1/2015165.0040.1187500mg/l
10/1/2015170.0040.1337500mg/l
11/1/2015148.0050.1475800mg/l
12/1/201550.0040.1380000mg/l
1/1/201677.5040.1342500mg/l
2/1/201677.5040.1146700mg/l
3/1/201675.0040.0996700mg/l
4/1/201665.0040.0821700mg/l
5/1/201685.0040.0716700mg/l
6/1/2016115.0040.0825000mg/l
7/1/201670.0040.0812500mg/l
8/1/201697.5040.0845800mg/l
9/1/2016242.5040.1125000mg/l
10/1/2016182.5040.1320800mg/l
11/1/201667.5040.1291700mg/l
12/1/201678.0050.1230000mg/l
Loading Chart...
Target
0.17 mg/l
Threshold
0.18 mg/l

Dissolved Oxygen

Units: mg/l Year
2016
Historical
period of record
High 7.90 9.20
Mean 6.16 6.19 1.05196
Low 3.80 2.10
No. of Samples 48 656

Five-year Trend Graph

     
1/1/20127.1847.1800000mg/l
2/1/20126.7046.9400000mg/l
3/1/20126.7046.8600000mg/l
4/1/20126.2846.7200000mg/l
5/1/20125.9346.5600000mg/l
6/1/20125.7546.4200000mg/l
7/1/20125.2846.1100000mg/l
8/1/20124.7845.7900000mg/l
9/1/20124.9545.5000000mg/l
10/1/20125.1045.3000000mg/l
11/1/20125.5045.2300000mg/l
12/1/20126.0045.2700000mg/l
1/1/20136.2345.4300000mg/l
2/1/20137.5345.8900000mg/l
3/1/20137.1846.2600000mg/l
4/1/20136.4546.4800000mg/l
5/1/20136.2846.6100000mg/l
6/1/20134.1846.3100000mg/l
7/1/20135.5846.2000000mg/l
8/1/20134.8545.7500000mg/l
9/1/20135.6545.5000000mg/l
10/1/20135.5545.3500000mg/l
11/1/20136.4845.3800000mg/l
12/1/20136.8045.8200000mg/l
1/1/20146.7046.0100000mg/l
2/1/20147.1846.3900000mg/l
3/1/20146.5046.5400000mg/l
4/1/20146.4546.6900000mg/l
5/1/20146.7346.7300000mg/l
6/1/20145.6346.5300000mg/l
7/1/20145.2046.2800000mg/l
8/1/20143.2045.6200000mg/l
9/1/20145.2845.4200000mg/l
10/1/20144.4045.0700000mg/l
11/1/20146.8845.1000000mg/l
12/1/20147.0845.3400000mg/l
1/1/20155.9045.4600000mg/l
2/1/20158.1346.2800000mg/l
3/1/20157.1346.5900000mg/l
4/1/20156.8547.0000000mg/l
5/1/20156.6046.9500000mg/l
6/1/20155.6346.7100000mg/l
7/1/20156.0546.7300000mg/l
8/1/20155.2846.2600000mg/l
9/1/20155.1345.9200000mg/l
10/1/20155.2545.6600000mg/l
11/1/20155.0345.4000000mg/l
12/1/20156.8345.6000000mg/l
1/1/20167.3545.8100000mg/l
2/1/20167.0546.1100000mg/l
3/1/20166.7846.3800000mg/l
4/1/20167.2546.7200000mg/l
5/1/20166.0346.8800000mg/l
6/1/20165.5546.6700000mg/l
7/1/20165.7346.4000000mg/l
8/1/20165.1546.0800000mg/l
9/1/20165.5045.8700000mg/l
10/1/20166.0545.6700000mg/l
11/1/20166.3045.7100000mg/l
12/1/20165.1545.6500000mg/l
Loading Chart...
Target
mg/l
Threshold
0.00 mg/l

Light Attenuation

Units: K(1/m) Year
2016
Historical
period of record
High 6.46 9.04
Mean 1.57 1.14 0.94835
Low 0.29 0.06
No. of Samples 42 642

Five-year Trend Graph

     
1/1/20120.9940.9900000K(1/m)
2/1/20120.7540.8700000K(1/m)
3/1/20120.8440.8600000K(1/m)
4/1/20120.5540.7800000K(1/m)
5/1/20120.5640.7400000K(1/m)
6/1/20120.8640.7600000K(1/m)
7/1/20121.7140.8800000K(1/m)
8/1/20121.0840.9300000K(1/m)
9/1/20121.7241.0800000K(1/m)
10/1/20121.5541.2500000K(1/m)
11/1/20121.0241.3200000K(1/m)
12/1/20120.7641.3100000K(1/m)
1/1/20130.8041.1600000K(1/m)
2/1/20130.7041.0900000K(1/m)
3/1/20130.7940.9400000K(1/m)
4/1/20130.5040.7600000K(1/m)
5/1/20130.8140.7300000K(1/m)
6/1/20131.1740.8000000K(1/m)
7/1/20132.9041.1500000K(1/m)
8/1/20131.5141.2800000K(1/m)
9/1/20131.9641.4800000K(1/m)
10/1/20131.9841.7200000K(1/m)
11/1/20130.8441.7300000K(1/m)
12/1/20130.4941.6100000K(1/m)
1/1/20140.5541.2200000K(1/m)
2/1/20140.7041.0900000K(1/m)
3/1/20140.7540.8900000K(1/m)
4/1/20140.9240.7100000K(1/m)
5/1/20141.2740.7800000K(1/m)
6/1/20141.1340.8900000K(1/m)
7/1/20140.7740.9200000K(1/m)
8/1/20141.5241.0600000K(1/m)
9/1/20140.8841.0800000K(1/m)
10/1/20143.2541.4700000K(1/m)
11/1/20140.8141.3900000K(1/m)
12/1/20141.2141.4100000K(1/m)
1/1/20150.7641.4100000K(1/m)
2/1/20151.2041.3500000K(1/m)
3/1/20150.7241.3300000K(1/m)
4/1/20150.7140.9000000K(1/m)
5/1/20150.7940.9000000K(1/m)
6/1/20151.1140.8800000K(1/m)
7/1/20150.6840.8700000K(1/m)
8/1/20152.9341.1600000K(1/m)
9/1/20153.1141.5600000K(1/m)
10/1/20152.2741.8200000K(1/m)
11/1/20151.6141.9500000K(1/m)
12/1/20150.8541.9100000K(1/m)
1/1/20160.6541.9000000K(1/m)
2/1/20161.5241.6700000K(1/m)
3/1/20160.9141.3000000K(1/m)
4/1/20160.9141.0800000K(1/m)
5/1/20160.8940.9600000K(1/m)
6/1/20161.1341.0000000K(1/m)
7/1/20160.8241.0300000K(1/m)
8/1/20162.3641.1700000K(1/m)
9/1/20164.0141.6900000K(1/m)
10/1/20162.9042.0200000K(1/m)
12/1/20160.7722.1700000K(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 57.83 66.45
Mean 44.5 14.7888125410266
Low 17.62
No. of Samples 364 4,887

Five-year Trend Graph

     
1/1/20120.36290.3600000inches
2/1/20121.10291.1000000inches
3/1/20121.52311.5200000inches
4/1/20122.25242.2500000inches
5/1/20122.18312.1800000inches
6/1/201214.143014.1400000inches
7/1/20127.30317.3000000inches
8/1/201212.423112.4200000inches
9/1/20125.23305.2300000inches
10/1/20123.36313.3600000inches
11/1/20120.20280.2000000inches
12/1/20121.91311.9100000inches
1/1/20130.48310.4800000inches
2/1/20130.96230.9600000inches
3/1/20131.85301.8500000inches
4/1/20133.99303.9900000inches
5/1/20136.07316.0700000inches
6/1/201312.383012.3800000inches
7/1/201311.343111.3400000inches
8/1/20138.62318.6200000inches
9/1/201312.073012.0700000inches
10/1/20132.37312.3700000inches
11/1/20130.94300.9400000inches
12/1/20130.35310.3500000inches
1/1/20142.90312.9000000inches
2/1/20141.23281.2300000inches
3/1/20144.70314.7000000inches
4/1/20141.30291.3000000inches
5/1/20145.37315.3700000inches
6/1/20144.82304.8200000inches
7/1/20146.62316.6200000inches
8/1/20146.26286.2600000inches
9/1/201411.602611.6000000inches
10/1/20144.11304.1100000inches
11/1/20143.59303.5900000inches
12/1/20140.16310.1600000inches
1/1/20151.17311.1700000inches
2/1/20153.61283.6100000inches
3/1/20151.21311.2100000inches
4/1/20151.35301.3500000inches
5/1/20154.40314.4000000inches
6/1/20155.01305.0100000inches
7/1/201514.963114.9600000inches
8/1/20157.70317.7000000inches
9/1/20158.51308.5100000inches
10/1/20155.31315.3100000inches
11/1/20150.75300.7500000inches
12/1/20152.01312.0100000inches
1/1/20167.53317.5300000inches
2/1/20162.38292.3800000inches
3/1/20162.33312.3300000inches
4/1/20160.82300.8200000inches
5/1/20166.67316.6700000inches
6/1/20167.24307.2400000inches
7/1/20167.33317.3300000inches
8/1/201611.563111.5600000inches
9/1/20166.78306.7800000inches
10/1/20164.96314.9600000inches
11/1/20160.06280.0600000inches
12/1/20160.17310.1700000inches
Loading Chart...
Target
inches/yr
Threshold
inches/yr

Salinity

Units: PSS Year
2016
Historical
period of record
High 36.00 38.50
Mean 26.18 30.24 8.27409
Low 0.16 0.10
No. of Samples 48 656

Five-year Trend Graph

     
1/1/201234.48434.4800000PSS
2/1/201233.90434.1900000PSS
3/1/201235.33434.5700000PSS
4/1/201236.23434.9900000PSS
5/1/201236.45435.2800000PSS
6/1/201234.53435.1500000PSS
7/1/201220.68432.8500000PSS
8/1/201226.73431.6600000PSS
9/1/201224.53429.8600000PSS
10/1/201231.03428.9900000PSS
11/1/201229.40427.8200000PSS
12/1/201233.33427.6200000PSS
1/1/201333.03429.6800000PSS
2/1/201334.18430.9200000PSS
3/1/201334.30432.5500000PSS
4/1/201333.88433.0200000PSS
5/1/201333.08433.6300000PSS
6/1/201329.38432.9800000PSS
7/1/201313.60429.7400000PSS
8/1/201321.45427.6200000PSS
9/1/201320.38425.3000000PSS
10/1/201316.53422.4000000PSS
11/1/201332.15422.2500000PSS
12/1/201333.73422.9700000PSS
1/1/201433.78426.3400000PSS
2/1/201432.18428.1300000PSS
3/1/201434.23430.4300000PSS
4/1/201431.43432.9200000PSS
5/1/201430.53432.6500000PSS
6/1/201433.20432.5600000PSS
7/1/201431.40432.1600000PSS
8/1/201427.60431.4000000PSS
9/1/201430.05430.7000000PSS
10/1/201413.95427.7900000PSS
11/1/201431.33427.9200000PSS
12/1/201431.93427.7100000PSS
1/1/201532.53427.9000000PSS
2/1/201529.93428.2900000PSS
3/1/201530.60428.3800000PSS
4/1/201533.55431.6500000PSS
5/1/201534.38432.1500000PSS
6/1/201529.78431.8000000PSS
7/1/201533.65431.9800000PSS
8/1/201516.60429.7600000PSS
9/1/201514.70427.1100000PSS
10/1/201518.60424.6200000PSS
11/1/201521.23422.4300000PSS
12/1/201533.15422.9900000PSS
1/1/201631.60422.6500000PSS
2/1/201620.93423.3700000PSS
3/1/201633.35426.4800000PSS
4/1/201633.20428.9100000PSS
5/1/201631.03430.5400000PSS
6/1/201626.30429.4000000PSS
7/1/201632.63429.5700000PSS
8/1/201623.93430.0700000PSS
9/1/20166.09425.5300000PSS
10/1/201611.23421.8700000PSS
11/1/201632.85422.1700000PSS
12/1/201631.00422.9600000PSS
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Turbidity

Units: NTU Year
2016
Historical
period of record
High 14.00 23.00
Mean 4.34 4.24 2.64557
Low 1.10 0.35
No. of Samples 49 689

Five-year Trend Graph

     
1/1/20123.0843.0800000NTU
2/1/20123.7343.4100000NTU
3/1/20126.1734.3300000NTU
4/1/20125.0344.5000000NTU
5/1/20125.4344.6900000NTU
6/1/20124.4044.6400000NTU
7/1/20123.8344.7700000NTU
8/1/20123.1544.6700000NTU
9/1/20123.4454.2100000NTU
10/1/20123.3043.9300000NTU
11/1/20123.5853.6200000NTU
12/1/20123.4843.4600000NTU
1/1/20132.9343.3100000NTU
2/1/20133.4543.3600000NTU
3/1/20137.4544.0300000NTU
4/1/20132.4843.9000000NTU
5/1/20135.4044.2000000NTU
6/1/20133.9344.2700000NTU
7/1/20132.9544.2800000NTU
8/1/20132.9344.1900000NTU
9/1/20134.3343.6700000NTU
10/1/20136.0344.2600000NTU
11/1/20135.4544.2700000NTU
12/1/20133.5044.2000000NTU
1/1/20144.3544.4300000NTU
2/1/20142.8544.4200000NTU
3/1/20143.3944.2600000NTU
4/1/20148.7844.7200000NTU
5/1/20143.7544.4400000NTU
6/1/20144.8044.6500000NTU
7/1/20143.9544.5900000NTU
8/1/20144.9844.9400000NTU
9/1/20143.1344.9000000NTU
10/1/20144.3844.1700000NTU
11/1/20143.6044.1400000NTU
12/1/20147.2044.5400000NTU
1/1/20155.0454.7200000NTU
2/1/20156.7545.0200000NTU
3/1/20154.2345.2000000NTU
4/1/20153.9345.1300000NTU
5/1/20155.8845.5100000NTU
6/1/20154.5045.0600000NTU
7/1/20154.6044.9800000NTU
8/1/20154.3844.5900000NTU
9/1/20153.6844.5000000NTU
10/1/20153.6344.4500000NTU
11/1/20153.1854.0000000NTU
12/1/20153.2843.7900000NTU
1/1/20162.7843.4900000NTU
2/1/20163.7343.3800000NTU
3/1/20168.5344.1900000NTU
4/1/20167.5344.8400000NTU
5/1/20164.1345.0000000NTU
6/1/20163.8045.0800000NTU
7/1/20164.1845.3200000NTU
8/1/20163.6545.3000000NTU
9/1/20163.2044.4200000NTU
10/1/20164.9543.9900000NTU
11/1/20162.6543.7400000NTU
12/1/20163.3053.6600000NTU
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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 »

Loading interactive contour map viewer...
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
112 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 »

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

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