Table 16.  Maximum and minimum values observed for each parameter for the period January 9, 2012, through December 3, 2012.

Parameter

Maximum

Station/Date

Minimum

Station/Date

River Flow

 

 

 

 

      Des Moines River

13,900 ft3/s

7/07May12

91 ft3/s

1/08Oct12

      Raccoon River

8,790 ft3/s

10/27Jun11

220 ft3/s

10/05Dec11

Lake Level

 

 

 

 

      Saylorville Lake

836.74 ft NGVD

4S/23Apr12

832.42 ft NGVD

4S/03Dec12

      Lake Red Rock

743.03 ft NGVD

8S/03Dec12

741.93 ft NGVD

8S/08Oct12

Secchi Disc Depth

 

 

 

 

      Saylorville Lake

0.93 m

4S/25Jun12

0.30 m

4S/02Apr12

      Lake Red Rock

1.00 m

8S/11Jun12

0.12 m

8S/23Apr12

Transparency tube depth

96.5 cm

6/09Jan12

2.0 cm

10/07May12

Water temperature

31.8°C (89.2°F)

8S/09Jul12

0.0°C (32.0°F)

1/06Feb12

pH

8.80

10/09Jul12

7.32

4B/04Sep12

Carbon dioxide

38.5 mg/l

.9 mg/l

4B/04Sep12

0.0 mg/l

many

Phenolphthalein alkalinity

18 mg/l as CaCO3

7/16Jul12

0 mg/l as CaCO3

most

Total alkalinity

247 mg/l as CaCO3

1/06Feb12

112 mg/l as CaCO3

1/05Mar12

Specific Conductance

905 µS/cm

1/03Dec12

370 µS/cm

1/05Mar12

Dissolved oxygen

18.24 mg/l

7/23Jul12

0.50 mg/l

8B/04Sep12

D.O. saturation

251% of saturation

7/23Jul12

6% of saturation

8B/04Sep12

BOD

11.4 mg/l

1/02Apr12

0.7 mg/l

10/09Jan12

Calcium hardness

 212 mg/l as CaCO3

1/06Feb12

85 mg/l as CaCO3

10/09Jul12

Total hardness

366 mg/l as CaCO3

1/06Feb12

152 mg/l as CaCO3

1/05Mar12

Turbidity

1,400 NTU

6/07May12

4 NTU

several

Suspended solids

5,890 mg/l

6/07May12

3 mg/l

9/09Jan12

Ammonia (as N)

1.67 mg/l

4B/23Jul12

<0.01 mg/l

several

Un-ionized ammonia (as N)

0.053 mg/l

8S/18Jun12

 

<0.001 mg/l

several

Table 16.  Continued. 

Parameter

Maximum

Station/Date

Minimum

Station/Date

NO2 +NO3 (as N)

11.7 mg/l

1/25Jun12

0.05  mg/l

1/02Apr12

Organic nitrogen (as N)

5.32 mg/l

6/07May12

0.17 mg/l

8S/05Nov12

Total nitrogen (as N)

13.8 mg/l

1/25Jun12

1.00 mg/l

1/08Oct12

TOC

14 mg/l

1/05May12

3 mg/l

several

Dissolved silica (as SiO2)

25.3 mg/l

1/04Sep12

0.30 mg/l

1/26Mar12

Total phosphate (as PO4)

6.25 mg/l

6/07May12

<0.01 mg/l

9/08Oct12

Total Phosphorus (as P)

2.04 mg/l

6/07May12

<0.01 mg/l

9/08Oct12

Orthophosphate (as PO4)

4.11 mg/l

7/08Oct12

<0.01 mg/l

1&10/a few

Orthophosphorus (as P)

1.34 mg/l

7/08Oct12

<0.01 mg/l

1&10/a few

Soluble cadmium

LTDL a

all

 

LTDL a

all

 

Soluble copper

5 µg/l

5/26Mar12

2 µg/l

10/26Mar12

Soluble lead

2 µg/l

A few

 

LTDL a

several

Soluble mercury

LTDL a

all

LTDL a

all

Chlorophyll a

207 mg/m3

7/16Jul12

6 mg/m3

9/04Sep12

Chlorophyll b

19 mg/m3

10/09Jul12

0 mg/m3

several

Chlorophyll c

56 mg/m3

10/11Jun12

0 mg/m3

a few

Pheophytin a

30 mg/m3

1/07May12

0 mg/m3

a few

Corrected chlorophyll a

193 mg/m3

8S/11Jun12

3 mg/m3

9/17Sep12

Fecal coliform

>2,000/100 ml

8S/09Jul12

<1/100 ml

4S&8S/many

Escherichia coli

>2,000/100 ml

8S/09Jul12

<1/100 ml

4S&8S/many

Total gas saturation b

123.3% of saturation

9/18Jun12

99.9% of saturation

5/09Jan12

Nitrogen gas saturation b

128.7% of saturation

9/18Jun12

97.1% of saturation

9/23Jul12

aLTDL—less than detection limit.

bFrom Stations 5, 8S and 9 only.

Table 16.  Continued.

Parameter

Maximum

Station/Date

Minimum

Station/Date

TSI (Chlorophyll) c,d

76

 

8S/11Jun12

50

8S/17Sep12

TSI (Phosphorus) c,d

100

8S/26Mar12

59

8S/04Sep12

TSI (Secchi) c,d

91

8S/23Apr12

60

8S/11Jun12

Water quality index e

91

5&6/once

51

7/16Jul12

 

c From Stations 4S and 8S only.

d TSI, lower index value, better water quality.

e WQI, higher index value, better water quality.