Sarasota County Water Atlas

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Dona/Roberts Bay Condition Report for 2015

View 2014 Report View 2016 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:

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.

Bays included in this report:

• Dona Bay
• Lyons Bay
• Roberts Bay Venice

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
Target	0.0043	0.0043
Threshold	0.0049	0.0049
MDL	0.0005	0.0005
GeoMean	0.0054	0.0054

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• Data Sources: Sarasota County

Five-year Trend Graph

1/1/2011	3.01	4	0.0030100	mg/l
2/1/2011	4.88	4	0.0039500	mg/l
3/1/2011	1.82	4	0.0032400	mg/l
4/1/2011	5.08	4	0.0037000	mg/l
5/1/2011	4.99	4	0.0039600	mg/l
6/1/2011	5.98	4	0.0042900	mg/l
7/1/2011	7.18	4	0.0049900	mg/l
8/1/2011	7.97	4	0.0055000	mg/l
9/1/2011	7.80	4	0.0065000	mg/l
10/1/2011	8.39	4	0.0070500	mg/l
11/1/2011	3.56	4	0.0068100	mg/l
12/1/2011	1.88	4	0.0061300	mg/l
1/1/2012	2.03	4	0.0052700	mg/l
2/1/2012	2.03	4	0.0042800	mg/l
3/1/2012	2.04	4	0.0033200	mg/l
4/1/2012	1.18	4	0.0021200	mg/l
5/1/2012	3.12	4	0.0020500	mg/l
6/1/2012	5.49	4	0.0026500	mg/l
7/1/2012	7.39	4	0.0035400	mg/l
8/1/2012	8.51	4	0.0046200	mg/l
9/1/2012	5.22	5	0.0051500	mg/l
10/1/2012	5.10	4	0.0058100	mg/l
11/1/2012	4.11	5	0.0059700	mg/l
12/1/2012	1.83	4	0.0053600	mg/l
1/1/2013	6.04	4	0.0051400	mg/l
2/1/2013	1.82	4	0.0040200	mg/l
3/1/2013	2.34	4	0.0035400	mg/l
4/1/2013	1.98	4	0.0030200	mg/l
5/1/2013	2.59	4	0.0027700	mg/l
6/1/2013	10.65	4	0.0042400	mg/l
7/1/2013	11.09	4	0.0050800	mg/l
8/1/2013	8.63	4	0.0062100	mg/l
9/1/2013	6.91	4	0.0069800	mg/l
10/1/2013	18.98	4	0.0098100	mg/l
11/1/2013	3.95	4	0.0100400	mg/l
12/1/2013	4.04	4	0.0089300	mg/l
1/1/2014	3.19	4	0.0076200	mg/l
2/1/2014	2.08	4	0.0065300	mg/l
3/1/2014	2.16	4	0.0057300	mg/l
4/1/2014	2.33	4	0.0029600	mg/l
5/1/2014	5.31	4	0.0031900	mg/l
6/1/2014	7.41	4	0.0037500	mg/l
7/1/2014	6.99	4	0.0043800	mg/l
8/1/2014	4.51	4	0.0047900	mg/l
9/1/2014	5.67	4	0.0053700	mg/l
10/1/2014	15.31	4	0.0075300	mg/l
11/1/2014	4.61	4	0.0074200	mg/l
12/1/2014	5.72	4	0.0071400	mg/l
1/1/2015	3.53	5	0.0065600	mg/l
2/1/2015	3.44	4	0.0063800	mg/l
3/1/2015	2.78	4	0.0059000	mg/l
4/1/2015	2.23	4	0.0037200	mg/l
5/1/2015	2.95	4	0.0034400	mg/l
6/1/2015	8.76	4	0.0039500	mg/l
7/1/2015	6.05	4	0.0043700	mg/l
8/1/2015	12.25	4	0.0058400	mg/l
9/1/2015	12.77	4	0.0075000	mg/l
10/1/2015	17.05	4	0.0099700	mg/l
11/1/2015	9.79	5	0.0111100	mg/l
12/1/2015	5.26	4	0.0105300	mg/l

Target
0.0043 mg/l

Threshold
0.0049 mg/l

Method Detection Limit
0.0005 mg/l

×

Chlorophyll a

The rating for Chlorophyll a is determined by comparing the annual arithmetic mean of its sampled values to fixed target and threshold values. The annual arithmetic mean is shown in the graph at left, as compared to its established target and threshold values.

An arithmetic mean is used for Chlorophyll a for consistency with the Surface Water Quality Standards, Florida Administrative Code 62-302.532, Estuary-Specific Numeric Interpretations of the Narrative Nutrient Criterion.

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
Target	0.40	0.40
Threshold	0.42	0.42
MDL
GeoMean	0.4726	0.4726

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• Data Sources: Sarasota County

Five-year Trend Graph

1/1/2011	268.00	4	0.2680000	mg/l
2/1/2011	319.50	4	0.2937500	mg/l
3/1/2011	387.75	4	0.3250800	mg/l
4/1/2011	444.25	4	0.3548800	mg/l
5/1/2011	422.50	4	0.3684000	mg/l
6/1/2011	373.25	4	0.3692100	mg/l
7/1/2011	426.25	4	0.3955800	mg/l
8/1/2011	647.50	4	0.4502500	mg/l
9/1/2011	848.50	4	0.5270400	mg/l
10/1/2011	445.50	4	0.5272500	mg/l
11/1/2011	358.75	4	0.5166300	mg/l
12/1/2011	298.75	4	0.5042100	mg/l
1/1/2012	275.50	4	0.4790800	mg/l
2/1/2012	349.00	4	0.4293300	mg/l
3/1/2012	337.50	4	0.3441700	mg/l
4/1/2012	270.00	4	0.3149200	mg/l
5/1/2012	260.00	4	0.2984600	mg/l
6/1/2012	267.50	4	0.2932500	mg/l
7/1/2012	809.00	4	0.3821700	mg/l
8/1/2012	543.00	4	0.4145000	mg/l
9/1/2012	727.40	5	0.4794800	mg/l
10/1/2012	503.00	4	0.5183200	mg/l
11/1/2012	494.60	5	0.5574200	mg/l
12/1/2012	240.00	4	0.5528300	mg/l
1/1/2013	351.50	4	0.4765800	mg/l
2/1/2013	258.00	4	0.4290800	mg/l
3/1/2013	175.00	4	0.3370200	mg/l
4/1/2013	275.25	4	0.2990600	mg/l
5/1/2013	397.50	4	0.2828800	mg/l
6/1/2013	615.25	4	0.3454200	mg/l
7/1/2013	1016.25	4	0.4562100	mg/l
8/1/2013	850.25	4	0.5549200	mg/l
9/1/2013	770.75	4	0.6542100	mg/l
10/1/2013	987.50	4	0.7729200	mg/l
11/1/2013	418.25	4	0.7763800	mg/l
12/1/2013	401.00	4	0.7406700	mg/l
1/1/2014	353.50	4	0.6302100	mg/l
2/1/2014	396.25	4	0.5545400	mg/l
3/1/2014	365.25	4	0.4869600	mg/l
4/1/2014	420.25	4	0.3924200	mg/l
5/1/2014	425.25	4	0.3935800	mg/l
6/1/2014	530.00	4	0.4150800	mg/l
7/1/2014	470.75	4	0.4346300	mg/l
8/1/2014	758.00	4	0.4949200	mg/l
9/1/2014	614.25	4	0.5364200	mg/l
10/1/2014	1019.50	4	0.6362900	mg/l
11/1/2014	462.75	4	0.6425400	mg/l
12/1/2014	473.50	4	0.6331300	mg/l
1/1/2015	504.00	5	0.6386700	mg/l
2/1/2015	315.50	4	0.5649200	mg/l
3/1/2015	340.00	4	0.5192100	mg/l
4/1/2015	180.00	4	0.3792900	mg/l
5/1/2015	372.75	4	0.3642900	mg/l
6/1/2015	535.00	4	0.3745400	mg/l
7/1/2015	414.00	4	0.3595400	mg/l
8/1/2015	995.25	4	0.4728300	mg/l
9/1/2015	950.75	4	0.5746300	mg/l
10/1/2015	797.00	4	0.6774600	mg/l
11/1/2015	814.60	5	0.7511000	mg/l
12/1/2015	339.75	4	0.7185600	mg/l

Target
0.40 mg/l

Threshold
0.42 mg/l

Method Detection Limit
mg/l

×

Nitrogen, Total

The rating for Total Nitrogen is determined by comparing the annual arithmetic mean of its sampled values to fixed target and threshold values. The annual arithmetic mean is shown in the graph at left, as compared to its established target and threshold values.

An arithmetic mean is used for Total Nitrogen for consistency with the Surface Water Quality Standards, Florida Administrative Code 62-302.532, Estuary-Specific Numeric Interpretations of the Narrative Nutrient Criterion.

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
Target	0.17	0.17
Threshold	0.18	0.18
MDL	0.0001	0.0001
GeoMean	0.0925	0.0925

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• Data Sources: Sarasota County

Five-year Trend Graph

1/1/2011	50.00	4	0.0500000	mg/l
2/1/2011	50.00	4	0.0500000	mg/l
3/1/2011	52.50	4	0.0508300	mg/l
4/1/2011	70.00	4	0.0556300	mg/l
5/1/2011	85.00	4	0.0615000	mg/l
6/1/2011	77.50	4	0.0641700	mg/l
7/1/2011	107.50	4	0.0737500	mg/l
8/1/2011	145.00	4	0.0895800	mg/l
9/1/2011	170.00	4	0.1091700	mg/l
10/1/2011	65.00	4	0.1083300	mg/l
11/1/2011	50.00	4	0.1025000	mg/l
12/1/2011	52.50	4	0.0983300	mg/l
1/1/2012	50.00	4	0.0887500	mg/l
2/1/2012	60.00	4	0.0745800	mg/l
3/1/2012	55.00	4	0.0554200	mg/l
4/1/2012	50.00	4	0.0529200	mg/l
5/1/2012	65.00	4	0.0554200	mg/l
6/1/2012	60.00	4	0.0566700	mg/l
7/1/2012	242.50	4	0.0887500	mg/l
8/1/2012	112.50	4	0.0975000	mg/l
9/1/2012	126.00	5	0.1093300	mg/l
10/1/2012	87.50	4	0.1155800	mg/l
11/1/2012	96.00	5	0.1207500	mg/l
12/1/2012	50.00	4	0.1190800	mg/l
1/1/2013	57.50	4	0.0882500	mg/l
2/1/2013	50.00	4	0.0778300	mg/l
3/1/2013	65.00	4	0.0676700	mg/l
4/1/2013	55.00	4	0.0622500	mg/l
5/1/2013	50.00	4	0.0545800	mg/l
6/1/2013	125.00	4	0.0670800	mg/l
7/1/2013	237.50	4	0.0970800	mg/l
8/1/2013	160.00	4	0.1154200	mg/l
9/1/2013	97.50	4	0.1208300	mg/l
10/1/2013	195.00	4	0.1441700	mg/l
11/1/2013	70.00	4	0.1475000	mg/l
12/1/2013	52.50	4	0.1354200	mg/l
1/1/2014	57.50	4	0.1054200	mg/l
2/1/2014	65.00	4	0.0895800	mg/l
3/1/2014	57.50	4	0.0829200	mg/l
4/1/2014	87.50	4	0.0650000	mg/l
5/1/2014	85.00	4	0.0675000	mg/l
6/1/2014	115.00	4	0.0779200	mg/l
7/1/2014	130.00	4	0.0900000	mg/l
8/1/2014	137.50	4	0.1020800	mg/l
9/1/2014	75.00	4	0.1050000	mg/l
10/1/2014	170.00	4	0.1187500	mg/l
11/1/2014	85.00	4	0.1187500	mg/l
12/1/2014	50.00	4	0.1079200	mg/l
1/1/2015	78.00	5	0.0992500	mg/l
2/1/2015	75.00	4	0.0888300	mg/l
3/1/2015	50.00	4	0.0846700	mg/l
4/1/2015	80.00	4	0.0696700	mg/l
5/1/2015	65.00	4	0.0663300	mg/l
6/1/2015	107.50	4	0.0759200	mg/l
7/1/2015	100.00	4	0.0795800	mg/l
8/1/2015	195.00	4	0.0995800	mg/l
9/1/2015	165.00	4	0.1187500	mg/l
10/1/2015	170.00	4	0.1337500	mg/l
11/1/2015	148.00	5	0.1475800	mg/l
12/1/2015	50.00	4	0.1380000	mg/l

Target
0.17 mg/l

Threshold
0.18 mg/l

Method Detection Limit
0.0001 mg/l

×

Phosphorus, Total

The rating for Total Phosphorus is determined by comparing the annual arithmetic mean of its sampled values to fixed target and threshold values. The annual arithmetic mean is shown in the graph at left, as compared to its established target and threshold values.

An arithmetic mean is used for Total Phosphorus for consistency with the Surface Water Quality Standards, Florida Administrative Code 62-302.532, Estuary-Specific Numeric Interpretations of the Narrative Nutrient Criterion.

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
Target
Threshold	0.00	0.00
MDL	0.20	0.20
GeoMean	6.0366	6.0366

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• Data Sources: Sarasota County

Five-year Trend Graph

1/1/2011	7.63	4	7.6300000	mg/l
2/1/2011	7.33	4	7.4800000	mg/l
3/1/2011	7.05	4	7.3400000	mg/l
4/1/2011	6.33	4	7.0900000	mg/l
5/1/2011	6.03	4	6.8700000	mg/l
6/1/2011	5.60	4	6.6600000	mg/l
7/1/2011	5.38	4	6.2900000	mg/l
8/1/2011	4.60	4	5.8300000	mg/l
9/1/2011	5.10	4	5.5100000	mg/l
10/1/2011	5.50	4	5.3700000	mg/l
11/1/2011	6.28	4	5.4100000	mg/l
12/1/2011	6.95	4	5.6400000	mg/l
1/1/2012	7.18	4	5.9400000	mg/l
2/1/2012	6.70	4	6.2900000	mg/l
3/1/2012	6.70	4	6.5500000	mg/l
4/1/2012	6.28	4	6.6800000	mg/l
5/1/2012	5.93	4	6.6200000	mg/l
6/1/2012	5.75	4	6.4200000	mg/l
7/1/2012	5.28	4	6.1100000	mg/l
8/1/2012	4.78	4	5.7900000	mg/l
9/1/2012	4.95	4	5.5000000	mg/l
10/1/2012	5.10	4	5.3000000	mg/l
11/1/2012	5.50	4	5.2300000	mg/l
12/1/2012	6.00	4	5.2700000	mg/l
1/1/2013	6.23	4	5.4300000	mg/l
2/1/2013	7.53	4	5.8900000	mg/l
3/1/2013	7.18	4	6.2600000	mg/l
4/1/2013	6.45	4	6.4800000	mg/l
5/1/2013	6.28	4	6.6100000	mg/l
6/1/2013	4.18	4	6.3100000	mg/l
7/1/2013	5.58	4	6.2000000	mg/l
8/1/2013	4.85	4	5.7500000	mg/l
9/1/2013	5.65	4	5.5000000	mg/l
10/1/2013	5.55	4	5.3500000	mg/l
11/1/2013	6.48	4	5.3800000	mg/l
12/1/2013	6.80	4	5.8200000	mg/l
1/1/2014	6.70	4	6.0100000	mg/l
2/1/2014	7.18	4	6.3900000	mg/l
3/1/2014	6.50	4	6.5400000	mg/l
4/1/2014	6.45	4	6.6900000	mg/l
5/1/2014	6.73	4	6.7300000	mg/l
6/1/2014	5.63	4	6.5300000	mg/l
7/1/2014	5.20	4	6.2800000	mg/l
8/1/2014	3.20	4	5.6200000	mg/l
9/1/2014	5.28	4	5.4200000	mg/l
10/1/2014	4.40	4	5.0700000	mg/l
11/1/2014	6.88	4	5.1000000	mg/l
12/1/2014	7.08	4	5.3400000	mg/l
1/1/2015	5.90	4	5.4600000	mg/l
2/1/2015	8.13	4	6.2800000	mg/l
3/1/2015	7.13	4	6.5900000	mg/l
4/1/2015	6.85	4	7.0000000	mg/l
5/1/2015	6.60	4	6.9500000	mg/l
6/1/2015	5.63	4	6.7100000	mg/l
7/1/2015	6.05	4	6.7300000	mg/l
8/1/2015	5.28	4	6.2600000	mg/l
9/1/2015	5.13	4	5.9200000	mg/l
10/1/2015	5.25	4	5.6600000	mg/l
11/1/2015	5.03	4	5.4000000	mg/l
12/1/2015	6.83	4	5.6000000	mg/l

Target
mg/l

Threshold
0.00 mg/l

Method Detection Limit
0.20 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
Target
Threshold	0.00	0.00
MDL	0.05	0.05
GeoMean	1.1153	1.1153

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• Data Sources: Sarasota County

Five-year Trend Graph

1/1/2011	1.27	4	1.2700000	K(1/m)
2/1/2011	1.07	4	1.1700000	K(1/m)
3/1/2011	0.80	4	1.0500000	K(1/m)
4/1/2011	1.13	4	1.0700000	K(1/m)
5/1/2011	0.97	4	1.0500000	K(1/m)
6/1/2011	0.80	4	1.0100000	K(1/m)
7/1/2011	0.96	4	0.9600000	K(1/m)
8/1/2011	1.11	4	0.9600000	K(1/m)
9/1/2011	1.85	4	1.1400000	K(1/m)
10/1/2011	1.23	4	1.1500000	K(1/m)
11/1/2011	0.84	4	1.1300000	K(1/m)
12/1/2011	0.63	4	1.1000000	K(1/m)
1/1/2012	0.99	4	1.1100000	K(1/m)
2/1/2012	0.75	4	1.0500000	K(1/m)
3/1/2012	0.84	4	0.8800000	K(1/m)
4/1/2012	0.55	4	0.7700000	K(1/m)
5/1/2012	0.56	4	0.7200000	K(1/m)
6/1/2012	0.86	4	0.7600000	K(1/m)
7/1/2012	1.71	4	0.8800000	K(1/m)
8/1/2012	1.08	4	0.9300000	K(1/m)
9/1/2012	1.72	4	1.0800000	K(1/m)
10/1/2012	1.55	4	1.2500000	K(1/m)
11/1/2012	1.02	4	1.3200000	K(1/m)
12/1/2012	0.76	4	1.3100000	K(1/m)
1/1/2013	0.80	4	1.1600000	K(1/m)
2/1/2013	0.70	4	1.0900000	K(1/m)
3/1/2013	0.79	4	0.9400000	K(1/m)
4/1/2013	0.50	4	0.7600000	K(1/m)
5/1/2013	0.81	4	0.7300000	K(1/m)
6/1/2013	1.17	4	0.8000000	K(1/m)
7/1/2013	2.90	4	1.1500000	K(1/m)
8/1/2013	1.51	4	1.2800000	K(1/m)
9/1/2013	1.96	4	1.4800000	K(1/m)
10/1/2013	1.98	4	1.7200000	K(1/m)
11/1/2013	0.84	4	1.7300000	K(1/m)
12/1/2013	0.49	4	1.6100000	K(1/m)
1/1/2014	0.55	4	1.2200000	K(1/m)
2/1/2014	0.70	4	1.0900000	K(1/m)
3/1/2014	0.75	4	0.8900000	K(1/m)
4/1/2014	0.92	4	0.7100000	K(1/m)
5/1/2014	1.27	4	0.7800000	K(1/m)
6/1/2014	1.13	4	0.8900000	K(1/m)
7/1/2014	0.77	4	0.9200000	K(1/m)
8/1/2014	1.52	4	1.0600000	K(1/m)
9/1/2014	0.88	4	1.0800000	K(1/m)
10/1/2014	3.25	4	1.4700000	K(1/m)
11/1/2014	0.81	4	1.3900000	K(1/m)
12/1/2014	1.21	4	1.4100000	K(1/m)
1/1/2015	0.76	4	1.4100000	K(1/m)
2/1/2015	1.20	4	1.3500000	K(1/m)
3/1/2015	0.72	4	1.3300000	K(1/m)
4/1/2015	0.71	4	0.9000000	K(1/m)
5/1/2015	0.79	4	0.9000000	K(1/m)
6/1/2015	1.11	4	0.8800000	K(1/m)
7/1/2015	0.68	4	0.8700000	K(1/m)
8/1/2015	2.93	4	1.1600000	K(1/m)
9/1/2015	3.11	4	1.5600000	K(1/m)
10/1/2015	2.27	4	1.8200000	K(1/m)
11/1/2015	1.61	4	1.9500000	K(1/m)
12/1/2015	0.85	4	1.9100000	K(1/m)

Target
K(1/m)

Threshold
0.00 K(1/m)

Method Detection Limit
0.05 K(1/m)

Rainfall

Units: inches/yr	Year 2015	Historical period of record
High	55.99	66.45
Mean		42.0 17.5513127985453
Low		5.43
No. of Samples	365	5,043
Target
Threshold
MDL
GeoMean

• Download Data
• Learn More
• Data Sources: Sarasota County

Five-year Trend Graph

1/1/2011	2.30	31	2.3000000	inches
2/1/2011	0.35	28	0.3500000	inches
3/1/2011	5.41	31	5.4100000	inches
4/1/2011	0.83	30	0.8300000	inches
5/1/2011	2.85	31	2.8500000	inches
6/1/2011	3.64	30	3.6400000	inches
7/1/2011	12.48	31	12.4800000	inches
8/1/2011	5.35	31	5.3500000	inches
9/1/2011	4.03	30	4.0300000	inches
10/1/2011	1.57	30	1.5700000	inches
11/1/2011	1.93	30	1.9300000	inches
12/1/2011	0.06	30	0.0600000	inches
1/1/2012	0.36	29	0.3600000	inches
2/1/2012	1.10	29	1.1000000	inches
3/1/2012	1.52	31	1.5200000	inches
4/1/2012	2.25	24	2.2500000	inches
5/1/2012	2.18	31	2.1800000	inches
6/1/2012	14.14	30	14.1400000	inches
7/1/2012	7.30	31	7.3000000	inches
8/1/2012	12.42	31	12.4200000	inches
9/1/2012	5.23	30	5.2300000	inches
10/1/2012	3.36	31	3.3600000	inches
11/1/2012	0.20	28	0.2000000	inches
12/1/2012	1.91	31	1.9100000	inches
1/1/2013	0.48	31	0.4800000	inches
2/1/2013	0.96	23	0.9600000	inches
3/1/2013	1.85	30	1.8500000	inches
4/1/2013	3.99	30	3.9900000	inches
5/1/2013	6.07	31	6.0700000	inches
6/1/2013	12.38	30	12.3800000	inches
7/1/2013	11.34	31	11.3400000	inches
8/1/2013	8.62	31	8.6200000	inches
9/1/2013	12.07	30	12.0700000	inches
10/1/2013	2.37	31	2.3700000	inches
11/1/2013	0.94	30	0.9400000	inches
12/1/2013	0.35	31	0.3500000	inches
1/1/2014	2.90	31	2.9000000	inches
2/1/2014	1.23	28	1.2300000	inches
3/1/2014	4.70	31	4.7000000	inches
4/1/2014	1.30	29	1.3000000	inches
5/1/2014	5.37	31	5.3700000	inches
6/1/2014	4.82	30	4.8200000	inches
7/1/2014	6.62	31	6.6200000	inches
8/1/2014	6.26	28	6.2600000	inches
9/1/2014	11.60	26	11.6000000	inches
10/1/2014	4.11	30	4.1100000	inches
11/1/2014	3.59	30	3.5900000	inches
12/1/2014	0.16	31	0.1600000	inches
1/1/2015	1.17	31	1.1700000	inches
2/1/2015	3.61	28	3.6100000	inches
3/1/2015	1.21	31	1.2100000	inches
4/1/2015	1.35	30	1.3500000	inches
5/1/2015	4.40	31	4.4000000	inches
6/1/2015	5.01	30	5.0100000	inches
7/1/2015	14.96	31	14.9600000	inches
8/1/2015	7.70	31	7.7000000	inches
9/1/2015	8.51	30	8.5100000	inches
10/1/2015	5.31	31	5.3100000	inches
11/1/2015	0.75	30	0.7500000	inches
12/1/2015	2.01	31	2.0100000	inches

Target
inches/yr

Threshold
inches/yr

Method Detection Limit
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
Target
Threshold
MDL	0.10	0.10
GeoMean	22.6258	22.6258

• Download Data
• Learn More
• Data Sources: Sarasota County

Five-year Trend Graph

1/1/2011	32.18	4	32.1800000	PSS
2/1/2011	32.63	4	32.4100000	PSS
3/1/2011	34.03	4	32.9500000	PSS
4/1/2011	32.00	4	32.7100000	PSS
5/1/2011	33.40	4	32.8500000	PSS
6/1/2011	34.98	4	33.2000000	PSS
7/1/2011	30.95	4	33.0000000	PSS
8/1/2011	30.20	4	32.5900000	PSS
9/1/2011	22.83	4	30.7300000	PSS
10/1/2011	30.55	4	30.4900000	PSS
11/1/2011	33.95	4	30.5800000	PSS
12/1/2011	33.63	4	30.3500000	PSS
1/1/2012	34.48	4	30.9400000	PSS
2/1/2012	33.90	4	31.5600000	PSS
3/1/2012	35.33	4	33.6400000	PSS
4/1/2012	36.23	4	34.5900000	PSS
5/1/2012	36.45	4	35.0000000	PSS
6/1/2012	34.53	4	35.1500000	PSS
7/1/2012	20.68	4	32.8500000	PSS
8/1/2012	26.73	4	31.6600000	PSS
9/1/2012	24.53	4	29.8600000	PSS
10/1/2012	31.03	4	28.9900000	PSS
11/1/2012	29.40	4	27.8200000	PSS
12/1/2012	33.33	4	27.6200000	PSS
1/1/2013	33.03	4	29.6800000	PSS
2/1/2013	34.18	4	30.9200000	PSS
3/1/2013	34.30	4	32.5500000	PSS
4/1/2013	33.88	4	33.0200000	PSS
5/1/2013	33.08	4	33.6300000	PSS
6/1/2013	29.38	4	32.9800000	PSS
7/1/2013	13.60	4	29.7400000	PSS
8/1/2013	21.45	4	27.6200000	PSS
9/1/2013	20.38	4	25.3000000	PSS
10/1/2013	16.53	4	22.4000000	PSS
11/1/2013	32.15	4	22.2500000	PSS
12/1/2013	33.73	4	22.9700000	PSS
1/1/2014	33.78	4	26.3400000	PSS
2/1/2014	32.18	4	28.1300000	PSS
3/1/2014	34.23	4	30.4300000	PSS
4/1/2014	31.43	4	32.9200000	PSS
5/1/2014	30.53	4	32.6500000	PSS
6/1/2014	33.20	4	32.5600000	PSS
7/1/2014	31.40	4	32.1600000	PSS
8/1/2014	27.60	4	31.4000000	PSS
9/1/2014	30.05	4	30.7000000	PSS
10/1/2014	13.95	4	27.7900000	PSS
11/1/2014	31.33	4	27.9200000	PSS
12/1/2014	31.93	4	27.7100000	PSS
1/1/2015	32.53	4	27.9000000	PSS
2/1/2015	29.93	4	28.2900000	PSS
3/1/2015	30.60	4	28.3800000	PSS
4/1/2015	33.55	4	31.6500000	PSS
5/1/2015	34.38	4	32.1500000	PSS
6/1/2015	29.78	4	31.8000000	PSS
7/1/2015	33.65	4	31.9800000	PSS
8/1/2015	16.60	4	29.7600000	PSS
9/1/2015	14.70	4	27.1100000	PSS
10/1/2015	18.60	4	24.6200000	PSS
11/1/2015	21.23	4	22.4300000	PSS
12/1/2015	33.15	4	22.9900000	PSS

Target
PSS

Threshold
PSS

Method Detection Limit
0.10 PSS

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
Target
Threshold
MDL	0.20	0.20
GeoMean	4.1358	4.1358

• Download Data
• Learn More
• Data Sources: Sarasota County

Five-year Trend Graph

1/1/2011	4.45	4	4.4500000	NTU
2/1/2011	8.93	4	6.6900000	NTU
3/1/2011	5.43	4	6.2700000	NTU
4/1/2011	11.48	4	7.5700000	NTU
5/1/2011	4.45	4	6.9500000	NTU
6/1/2011	3.48	4	6.3700000	NTU
7/1/2011	4.53	4	6.3800000	NTU
8/1/2011	6.80	4	6.0300000	NTU
9/1/2011	3.43	4	5.7000000	NTU
10/1/2011	3.28	4	4.3300000	NTU
11/1/2011	4.00	4	4.2500000	NTU
12/1/2011	3.70	4	4.2900000	NTU
1/1/2012	3.08	4	4.0500000	NTU
2/1/2012	3.73	4	3.5400000	NTU
3/1/2012	6.17	3	3.9900000	NTU
4/1/2012	5.03	4	4.2900000	NTU
5/1/2012	5.43	4	4.5200000	NTU
6/1/2012	4.40	4	4.6400000	NTU
7/1/2012	3.83	4	4.7700000	NTU
8/1/2012	3.15	4	4.6700000	NTU
9/1/2012	3.44	5	4.2100000	NTU
10/1/2012	3.30	4	3.9300000	NTU
11/1/2012	3.58	5	3.6200000	NTU
12/1/2012	3.48	4	3.4600000	NTU
1/1/2013	2.93	4	3.3100000	NTU
2/1/2013	3.45	4	3.3600000	NTU
3/1/2013	7.45	4	4.0300000	NTU
4/1/2013	2.48	4	3.9000000	NTU
5/1/2013	5.40	4	4.2000000	NTU
6/1/2013	3.93	4	4.2700000	NTU
7/1/2013	2.95	4	4.2800000	NTU
8/1/2013	2.93	4	4.1900000	NTU
9/1/2013	4.33	4	3.6700000	NTU
10/1/2013	6.03	4	4.2600000	NTU
11/1/2013	5.45	4	4.2700000	NTU
12/1/2013	3.50	4	4.2000000	NTU
1/1/2014	4.35	4	4.4300000	NTU
2/1/2014	2.85	4	4.4200000	NTU
3/1/2014	3.39	4	4.2600000	NTU
4/1/2014	8.78	4	4.7200000	NTU
5/1/2014	3.75	4	4.4400000	NTU
6/1/2014	4.80	4	4.6500000	NTU
7/1/2014	3.95	4	4.5900000	NTU
8/1/2014	4.98	4	4.9400000	NTU
9/1/2014	3.13	4	4.9000000	NTU
10/1/2014	4.38	4	4.1700000	NTU
11/1/2014	3.60	4	4.1400000	NTU
12/1/2014	7.20	4	4.5400000	NTU
1/1/2015	5.04	5	4.7200000	NTU
2/1/2015	6.75	4	5.0200000	NTU
3/1/2015	4.23	4	5.2000000	NTU
4/1/2015	3.93	4	5.1300000	NTU
5/1/2015	5.88	4	5.5100000	NTU
6/1/2015	4.50	4	5.0600000	NTU
7/1/2015	4.60	4	4.9800000	NTU
8/1/2015	4.38	4	4.5900000	NTU
9/1/2015	3.68	4	4.5000000	NTU
10/1/2015	3.63	4	4.4500000	NTU
11/1/2015	3.18	5	4.0000000	NTU
12/1/2015	3.28	4	3.7900000	NTU

Target
NTU

Threshold
NTU

Method Detection Limit
0.20 NTU

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 »

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 »

Showing Seagrass Coverage for:

1. 1948
2. 1999
3. 2001
4. 2004
5. 2006
6. 2008
7. 2010
8. 2012
9. 2014
10. 2016

Loading interactive seagrass coverage viewer...

Show/Hide Labels

Legend:

• Continuous Seagrass
• Patchy Seagrass

Year	Acres
1948	132.738072
1988	47.351
1994	58.637
1996	66.2119
1999	87.23853
2001	83.943443
2004	102.462343
2006	123.222818
2008	89.334667
2010	78.364281
2012	78.807574
2014	98.816992
2016	100.74333

Loading interactive chart...

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 »