Parameter

Value

Station

Date

Remarks

River Flow

        Des Moines River

102,000 ft^3/s

7

13Jul93

flood event

56,700 ft^3/s

6

19Jun84

pre-1993 maximum

13 ft³/s

5

25Jan77

drought conditions

        Raccoon River

31,500 ft³/s

10

19Jun90

flood event

30,200 ft³/s

10

13Jul93

flood event

53 ft³/s

10

12Jan68

drought conditions

Elevation

        Saylorville   Lake

891.78 ft NGVD

4S

13Jul93

high flow

888.59 ft NGVD

4S

11Jun91

high flow

832.61 ft NGVD

4S

17Jan79

low flow

        Lake Red Rock

782.63 ft NGVD

8S

13Jul93

high flow

779.60 ft NGVD

8S

26Jun84

high flow

720.00 ft NGVD

8S

08Feb77

drought conditions

Secchi Disc Depth

        Saylorville Lake

2.33 m

4S

13Jun84

data available from 1980

0.10 m

4S

28Apr87

        Lake Red Rock

4.80 m

8S

21Jun84

data available from 1980

0.06 m

8S

19Jun90

Transparency

tube depth

>120 cm

12.5 cm

9

1

24Jul01

09Oct01

began 2001

Water temperature

38.0°C (100.4°F)

6

24Aug71

thermal pollution

-0.4°C (31.6°F)

7 & 10

10Feb97 & 11Jan00

severe cold

pH

9.90

1

11Dec69

–

6.00

2^a

12Feb71

Station 2 was near Madrid

Parameter

Value

Station

Date

Remarks

Carbon dioxide

94.0 mg/l

4B

24Jul84

–

0.0 mg/l

several

periodically

when pH > 8.30

Phenolphthalein

59 mg/l

4-RIVER^a

11Dec69

Station 4-RIVER was near

alkalinity

Polk City

0 mg/l

several

often

when pH < 8.30

Total alkalinity

589 mg/l as CaCO₃

1

18Jan77

low flow

67 mg/l as CaCO₃

7

07Jul87

high flow

Dissolved oxygen

50.08 mg/l

8S

20Jan76

376% of saturation (reservoir)

28.90 mg/l

5

23Feb68

203% of saturation (river)

0.65 mg/l

0

25Jan77

 4.6% of saturation (river)

0.00 mg/l

4B

30Jul79

0% of saturation (reservoir)

Calcium hardness

493 mg/l as CaCO₃

5

02Jan85

low flow (winter)

58 mg/l as CaCO₃

1

25Jul89

intense productivity

Total hardness

766 mg/l as CaCO₃

5

02Jan85

low flow (winter)

108 mg/l as CaCO₃

9

30Aug77

high flow

Total organic carbon

341 mg/l

<1 mg/l

10

several

02Jun80

periodically

low flow

–

Specific conductance^a

1,827 ΅mhos/cm

1

18Jan77

low flow

236 ΅mhos/cm

10

19Mar79

high flow

Inorganic carbon^a

148 mg/l

1

18Jan77

low flow

13 mg/l

several

periodically

high flow

Suspended solids

12,490 mg/l

10

30May89

high flow (Raccoon River)

10,200 mg/l

7

06Jul82

high flow (Des Moines River)

<1 mg/l

several

a few

low flow (winter)

Parameter

Value

Station

Date

Remarks

Turbidity

20,000 NTU

10

15Jun82

high flow (Raccoon River)

6,400 NTU

7

06Jul82

high flow (Des Moines River)

1 NTU

several

a few

ice cover; high elevation

BOD

32.0 mg/l

6

23Feb77

low flow (waste)

30.2 mg/l

5

03May68

low flow (plankton)

<0.1 mg/l

several

periodically

under ice cover

COD^a

553 mg/l

10

16May74

high flow

0.0 mg/l

5

14Feb69

low flow

Organic nitrogen

13.0 mg/l

4

12Sep68

–

<0.01 mg/l

several

periodically

–

Ammonia nitrogen

22.4 mg/l

6

08Feb77

low flow (waste)

11.9 mg/l

1

01Feb77

low flow (waste)

4.17 mg/l

6

16Jan90

low flow

3.65 mg/l

4B

23Jul96

stratification

<0.01 mg/l

several

periodically

algal utilization

NO₂ (as N)^a

0.62 mg/l

3-RIVER^a

16Oct68

data from 1967–1976 only

<0.01 mg/l

many

often

–

NO₂ + NO₃ (as N)

18.1 mg/l

1

12Jun90

high flow (Des Moines River)

17.0 mg/l

10

20Jul82

high flow (Raccoon River)

<0.01 mg/l

several

periodically

low flow, algal utilization

Un-ionized ammonia

1.06 mg/l

0.742 mg/l

1

6

29Mar68

25Jan77

low flow, high pH

low flow

(as N)

0.22 mg/l

4S

07Nov89

low flow

0.115 mg/l

4B

23Jul96

stratification

<0.001 mg/l

several

periodically

high flow, low pH

Total nitrogen (as N)

27.9 mg/l

17.2 mg/l

0.20 mg/l

6

10

10

08Feb77

26Jun01

16May01

low flow (waste)

Parameter

Value

Station

Date

Remarks

Orthophosphate

14.7 mg/l

6

08Feb77

low flow (waste)

<0.01 mg/l

several

periodically

algal utilization

Total phosphate

17.3 mg/l

6

08Feb77

low flow (waste)

13.2 mg/l

10

19Mar79

high flow (runoff)

<0.01 mg/l

several

periodically

low flow

Dissolved silica (as SiO₂)

59.6 mg/l

9

23Aug72

diatom growth

<0.01 mg/l

several

periodically

algal utilization

Soluble arsenic^a

8.3 ΅g/l

5

10Jul90

–

LTDL^b

many

often

–

Soluble cadmium

6.4 ΅g/l

5

09Jul91

since May 1988

LTDL

most

often

method change

Soluble chromium^a

20 ΅g/l

1

13Jan87

–

LTDL

many

often

–

Soluble copper

72 ΅g/l

1

11Oct94

initiated in WY91

LTDL

a few

–

Soluble lead

22 ΅g/l

9

05Oct95

since May 1988

LTDL

most

often

method change

Soluble mercury

2.5 ΅g/l

10

28Apr82

–

LTDL

Many

often

–

Soluble zinc^a

479 ΅g/l

9

05Oct95

–

LTDL

a few

–

Chlorophyll a

880 mg/m³

1

165Nov67

river

297 mg/m³

3B

25Nov80

reservoir

0 mg/m³

several

periodically

high flow, turbid

Parameter

Value

Station

Date

Remarks

Chlorophyll b

354 mg/m³

4–RIVER^a

05Jan68

–

90 mg/m³

7

21Jun88

–

0 mg/m³

several

periodically

–

Chlorophyll c

77 mg/m³

64 mg/m³

1

4S

24Aug81

28Jan80

river

reservoir

0 mg/m³

several

periodically

–

Pheophytin a

264 mg/m³

1

30Mar81

river

73mg/m³

3B

22Sep80

reservoir

0 mg/m³

several

periodically

–

Fecal coliform bacteria

207,000/100 ml

10

12Sep78

high flow

200,000/100 ml

6

01Feb77

low flow

17,000/100 ml

WBB3

23Sep86

beach

>12,000/100 ml

3B

08Nov77

reservoir

<1/100 ml

several

periodically

in the reservoirs

Escherichia coli bacteria

700/100 ml

30/100 ml

10

WBB3

07Aug01

17Jul01

began 2001

Total gas saturation

98.5%

5

11Jan00

133.6%

9

24Aug93

Stations 5 and 9 only

Nitrogen gas saturation

99.0%

5

09Dec97

155.7%

9

06Jun95

Stations 5 and 9 only

Water quality index

30

7

01Nov83

high suspended solids

90

5

06Feb90

–