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Dona/Roberts Bay Condition Report for 2015

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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:

There was not improvement in the water quality parameters that indicate the level of nutrient pollution in Dona/Roberts Bay in 2015. However, dissolved oxygen levels did increase slightly, a positive sign. Chlorophyll a, total nitrogen, and total phosphorus all increased in value; phosphorus levels are well below the target value, but chlorophyll a and nitrogen are still above their respective threshold values, causing the bay to retain its “Caution” rating from 2014.

Water Quality: All three nutrient measures used in scoring water quality increased in 2015, a worsening trend. The mean chlorophyll a concentration in 2015 was .0072 mg/l, exceeding the threshold value of 0.0049 mg/l. Mean nitrogen concentration was 0.5511 mg/l, higher than the threshold of 0.420 mg/l. The annual mean concentration of phosphorus, although higher than in 2014, remained well below the threshold of 0.180 mg/l, at 0.1072 mg/l. The means for chlorophyll a, nitrogen and phosphorus were calculated as arithmetic means (per the Numeric Nutrient Criteria outlined in the Florida Administrative Code, section 62-302.532). In 2014, 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 2014 by the Southwest Florida Water Management District. The increase in total seagrass acreage in Dona/Roberts Bay was significant. Between 2012 and 2014 it increased from 79 to 99 acres, but is still slightly 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
2015
Historical
period of record
High 0.0478 0.0612
Mean 0.0072 0.0052 0.00576031 0.0043000000
Low 0.0013 0.0001
No. of Samples 50 641

Five-year Trend Graph

     
1/1/20113.0140.0030100mg/l
2/1/20114.8840.0039500mg/l
3/1/20111.8240.0032400mg/l
4/1/20115.0840.0037000mg/l
5/1/20114.9940.0039600mg/l
6/1/20115.9840.0042900mg/l
7/1/20117.1840.0049900mg/l
8/1/20117.9740.0055000mg/l
9/1/20117.8040.0065000mg/l
10/1/20118.3940.0070500mg/l
11/1/20113.5640.0068100mg/l
12/1/20111.8840.0061300mg/l
1/1/20122.0340.0052700mg/l
2/1/20122.0340.0042800mg/l
3/1/20122.0440.0033200mg/l
4/1/20121.1840.0021200mg/l
5/1/20123.1240.0020500mg/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
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
2015
Historical
period of record
High 1.621 1.715
Mean 0.5511 0.439 0.27315048 0.4000000000
Low 0.145 0.055
No. of Samples 50 637

Five-year Trend Graph

     
1/1/2011268.0040.2680000mg/l
2/1/2011319.5040.2937500mg/l
3/1/2011387.7540.3250800mg/l
4/1/2011444.2540.3548800mg/l
5/1/2011422.5040.3684000mg/l
6/1/2011373.2540.3692100mg/l
7/1/2011426.2540.3955800mg/l
8/1/2011647.5040.4502500mg/l
9/1/2011848.5040.5270400mg/l
10/1/2011445.5040.5272500mg/l
11/1/2011358.7540.5166300mg/l
12/1/2011298.7540.5042100mg/l
1/1/2012275.5040.4790800mg/l
2/1/2012349.0040.4293300mg/l
3/1/2012337.5040.3441700mg/l
4/1/2012270.0040.3149200mg/l
5/1/2012260.0040.2984600mg/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
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
2015
Historical
period of record
High 0.32 0.47
Mean 0.1072 0.124 0.07265045 0.1700000000
Low 0.05 0.05
No. of Samples 50 641

Five-year Trend Graph

     
1/1/201150.0040.0500000mg/l
2/1/201150.0040.0500000mg/l
3/1/201152.5040.0508300mg/l
4/1/201170.0040.0556300mg/l
5/1/201185.0040.0615000mg/l
6/1/201177.5040.0641700mg/l
7/1/2011107.5040.0737500mg/l
8/1/2011145.0040.0895800mg/l
9/1/2011170.0040.1091700mg/l
10/1/201165.0040.1083300mg/l
11/1/201150.0040.1025000mg/l
12/1/201152.5040.0983300mg/l
1/1/201250.0040.0887500mg/l
2/1/201260.0040.0745800mg/l
3/1/201255.0040.0554200mg/l
4/1/201250.0040.0529200mg/l
5/1/201265.0040.0554200mg/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
Loading Chart...
Target
0.17 mg/l
Threshold
0.18 mg/l

Dissolved Oxygen

Units: mg/l Year
2015
Historical
period of record
High 8.90 9.20
Mean 6.15 6.19 1.06221
Low 3.40 2.10
No. of Samples 48 608

Five-year Trend Graph

     
1/1/20117.6347.6300000mg/l
2/1/20117.3347.4800000mg/l
3/1/20117.0547.3400000mg/l
4/1/20116.3347.0900000mg/l
5/1/20116.0346.8700000mg/l
6/1/20115.6046.6600000mg/l
7/1/20115.3846.2900000mg/l
8/1/20114.6045.8300000mg/l
9/1/20115.1045.5100000mg/l
10/1/20115.5045.3700000mg/l
11/1/20116.2845.4100000mg/l
12/1/20116.9545.6400000mg/l
1/1/20127.1845.9400000mg/l
2/1/20126.7046.2900000mg/l
3/1/20126.7046.5500000mg/l
4/1/20126.2846.6800000mg/l
5/1/20125.9346.6200000mg/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
Loading Chart...
Target
mg/l
Threshold
0.00 mg/l

Light Attenuation

Units: K(1/m) Year
2015
Historical
period of record
High 6.05 9.04
Mean 1.39 1.11 0.90132
Low 0.43 0.06
No. of Samples 48 600

Five-year Trend Graph

     
1/1/20111.2741.2700000K(1/m)
2/1/20111.0741.1700000K(1/m)
3/1/20110.8041.0500000K(1/m)
4/1/20111.1341.0700000K(1/m)
5/1/20110.9741.0500000K(1/m)
6/1/20110.8041.0100000K(1/m)
7/1/20110.9640.9600000K(1/m)
8/1/20111.1140.9600000K(1/m)
9/1/20111.8541.1400000K(1/m)
10/1/20111.2341.1500000K(1/m)
11/1/20110.8441.1300000K(1/m)
12/1/20110.6341.1000000K(1/m)
1/1/20120.9941.1100000K(1/m)
2/1/20120.7541.0500000K(1/m)
3/1/20120.8440.8800000K(1/m)
4/1/20120.5540.7700000K(1/m)
5/1/20120.5640.7200000K(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)
Loading Chart...
Target
K(1/m)
Threshold
0.00 K(1/m)

Rainfall

Units: inches/yr Year
2015
Historical
period of record
High 55.99 61.42
Mean 42.63 14.0899562856621
Low 17.62
No. of Samples 365 4,798

Five-year Trend Graph

     
1/1/20112.30312.3000000inches
2/1/20110.35280.3500000inches
3/1/20115.41315.4100000inches
4/1/20110.83300.8300000inches
5/1/20112.85312.8500000inches
6/1/20113.64303.6400000inches
7/1/201112.483112.4800000inches
8/1/20115.35315.3500000inches
9/1/20114.03304.0300000inches
10/1/20111.57301.5700000inches
11/1/20111.93301.9300000inches
12/1/20110.06300.0600000inches
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
Loading Chart...
Target
inches/yr
Threshold
inches/yr

Salinity

Units: PSS Year
2015
Historical
period of record
High 36.10 38.50
Mean 27.39 30.56 7.9942
Low 0.40 0.10
No. of Samples 48 608

Five-year Trend Graph

     
1/1/201132.18432.1800000PSS
2/1/201132.63432.4100000PSS
3/1/201134.03432.9500000PSS
4/1/201132.00432.7100000PSS
5/1/201133.40432.8500000PSS
6/1/201134.98433.2000000PSS
7/1/201130.95433.0000000PSS
8/1/201130.20432.5900000PSS
9/1/201122.83430.7300000PSS
10/1/201130.55430.4900000PSS
11/1/201133.95430.5800000PSS
12/1/201133.63430.3500000PSS
1/1/201234.48430.9400000PSS
2/1/201233.90431.5600000PSS
3/1/201235.33433.6400000PSS
4/1/201236.23434.5900000PSS
5/1/201236.45435.0000000PSS
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
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Turbidity

Units: NTU Year
2015
Historical
period of record
High 12.00 23.00
Mean 4.41 4.23 2.66022
Low 2.00 0.35
No. of Samples 50 640

Five-year Trend Graph

     
1/1/20114.4544.4500000NTU
2/1/20118.9346.6900000NTU
3/1/20115.4346.2700000NTU
4/1/201111.4847.5700000NTU
5/1/20114.4546.9500000NTU
6/1/20113.4846.3700000NTU
7/1/20114.5346.3800000NTU
8/1/20116.8046.0300000NTU
9/1/20113.4345.7000000NTU
10/1/20113.2844.3300000NTU
11/1/20114.0044.2500000NTU
12/1/20113.7044.2900000NTU
1/1/20123.0844.0500000NTU
2/1/20123.7343.5400000NTU
3/1/20126.1733.9900000NTU
4/1/20125.0344.2900000NTU
5/1/20125.4344.5200000NTU
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
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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 (2015)

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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