Specific Pollution Issues and Water Quality Standards Pertaining to
Clear Lake
Jeff Kopaska and Nicole Eckles
A. Point-source
pollution sources
Water quality planning representatives from the Department of Natural Resources report that there are presently no permitted livestock facilities in the watershed. Also, there were no point source dischargers in the Clear Lake watershed within the last 5 years. During the last five years, the Clear Lake Sanitary District had one occurrence of bypass pumping into the lake. This occurred on June 20, 1998, and 250,000 gallons of pretreatment sewage were discharged into Clear Lake (Kevin Moeller, Clear Lake Sanitary District, pers. comm.). This bypass pumping added approximately 1.5 kg of phosphorus to the lake, or 0.02% of the lake’s annual average phosphorus budget. Additionally, during that same period, the City of Clear Lake had two occurrences of bypass pumping into the lake. The first one occurred in June 1995, and 126,000 gallons of pretreatment sewage were discharged into the lake. The second one occurred in June 1998, and 44,250 gallons of pretreatment sewage were discharged into the lake (Al Tompkins, IDNR-EPD, pers. comm.). These two events combined added around 1 kg of phosphorus to the lake, or about 0.01% of the lake’s annual average phosphorus budget.
Residential areas in the watershed can provide point sources of nutrients to the lake. Most residences in the cities of Clear Lake and Ventura, as well as the unincorporated areas bordering Clear Lake are thought to be connected to the Clear Lake Sanitary District. Residences in other rural or unincorporated areas of the watershed generally have septic systems. The Cerro Gordo County Environmental Health representative indicates that issues concerning septic systems in Cerro Gordo County are handled on a case-by-case basis. If a septic system is determined to not be in compliance, there are county and federal low-interest loan programs to assist in updating or replacing septic systems.
B. Water quality standards from Chapter 61 of the Iowa Administrative Code:
1. Designated Uses. Under the state water quality classification system the lakes are classified as Class A (primary body-contact recreation) and Class B (LW) (lakes and wetlands - wildlife, fish, aquatic and semiaquatic life, and secondary contact water uses).
2. Applicable Criteria
GENERAL WATER QUALITY
Waters shall be free from substances
attributable to point source wastewater discharges that will settle to form
sludge deposits.
Waters shall be free from floating
debris, oil, grease, scum, and other floating materials attributable to
wastewater discharges or agricultural practices in amounts sufficient to create
a nuisance.
Waters shall be free from materials
attributable to wastewater discharges or agricultural practices producing
objectionable color, odor or other aesthetically objectionable conditions.
Waters shall be free from substances
attributable to wastewater discharges or agricultural practices in
concentrations or combinations which are acutely toxic to human, animal, or
plant life.
Waters shall be free from
substances, attributable to wastewater discharges or agricultural practices, in
quantities which would produce undesirable or nuisance aquatic life.
A point source discharge shall not
increase turbidity of the receiving water by more than 25 Nephelometric units.
Total dissolved solids shall not exceed 750 mg/l in any lake or impoundment or in any stream with a flow rate three times the flow rate of upstream point source discharges.
CLASS A WATERS
Fecal coliform: 200 organisms/100 ml from April 1 to October 31.
pH: 6.5 to 9.0
CLASS B WATERS
pH: 6.5 to 9.0
Dissolved oxygen: not to be lower than 5.0 mg/l during at least 16 hours per day,
but not less than 4.0 mg/l at any time
Temperature: 32° C
Toxics Substances: see Table 1, units in micrograms/liter unless otherwise noted
Ammonia: see Table 2
C. Toxicity analyses
1. Benthic sediments. Dredging is a possible restoration technique for the western basin (Little Lake) of Clear Lake, so sediment samples were collected at four locations in that basin. One sample was taken near the inflow of Ventura Marsh; one was taken off the western shore of the Little Lake, near the Harbor Inn; one was taken off the northern shore of Little Lake; and the final one was taken just west of the channel between the Little Lake and main lake. Dredging or other activities may impact the sediments in Ventura Marsh, so one sample was also taken from sediments of Ventura Marsh. Water samples were taken at the same time and treated for elutriate analysis following procedures recommended to the University of Iowa Hygienic Laboratory by the U. S. Army Corps of Engineers (pers. comm., Sherri Marine). Heavy metals, pesticides and nutrients were analyzed by the University of Iowa Hygienic Laboratory in Iowa City. Results of these analyses, which indicate concerns, are listed in Table 3. Complete profiles and original data sheets are presented in Appendix 12.
Results shown in bold italics (Table 3) are chronic violations of Iowa Water Quality Standards. Cadmium and chromium do not occur naturally in Iowa, so the presence of these pollutants is probably the result of human activity in the watershed. Potential sources of these elements are nickel-cadmium batteries that were not properly disposed, leaching from chrome-plated metals, and trace sources in agricultural fertilizers. The presence of copper, lead and zinc may be the result of multiple sources, both natural- and human activity-derived. While a small percentage of the sources of these elements may be natural in origin, the majority is probably the result of human activity. Copper, lead and zinc are all micronutrients that may be found in small quantities in agricultural fertilizers. Copper has many other potential sources, due to its ubiquitous use in building materials. Other potential sources of lead included historic use of leaded gasolines, lead shot and lead fishing weights. Zinc is use extensively as a plating material for steel and other metals, and can be leached by acid rain, so trace amounts of this element are often present in storm water. (Ralph Turkle, IDNR-EPD, pers. comm.)
The presence of these pollutants indicates are issues that needs to be addressed, particularly if dredging is a restoration option. It is recommended that additional samples be taken in the future to determine the sources and the extent of these Water Quality Standard problems. If further testing show these pollutants to be persistent, it may impact the cost of lake dredging as a restoration option by requiring more stringent control over return water quality. Additionally, monitoring data (Appendix 5) showed very elevated concentrations of ammonia-nitrogen in water near the lake bottom. Hydraulic dredging would draw water from near the lake bottom, and this water would have elevated ammonia-nitrogen levels, thus elutriate water might pose another problem for return water quality.
After reviewing the data in Table 3, Ralph Turkle, IDNR-EPD summarized his recommendations by saying “... I think the report should not dismiss the metals as background levels. The pollutants should continue to be part of the total lake assessment with every attempt in the future to identify their likely source(s). In addition, any recommended lake restoration effort (hydraulic dredging) will be faced with addressing the return water quality and its impact on the lake.”
2. Fish flesh. Common carp, channel catfish, walleye, black bullhead and yellow bass were collected from Clear Lake by IDNR personnel on August 2, 1999. Filets from the collected fish were analyzed for pesticides by the University of Iowa Hygienic Laboratory in Iowa City. They found only one detectable levels of pesticide in one species of fish analyzed (DDE in channel catfish), but this level of detection was far below the state’s standard for a fish consumption advisory. This indicates that there is no reason for concern about contamination of fish from this lake with the listed chemicals. The list of chemicals analyzed and the results of these analyses on the original data sheets are presented in Appendix 13.
Literature
cited
Iowa Administrative Code. 1990. Water quality standards, 61:1.
Table 1. Criteria
for chemical constituents, for waters with Class B (LW) use designations. Units are in microgram/liter unless
otherwise noted. Source: Iowa
Administrative Code, Ch. 61, Water Quality Standards, November 1990.
Parameter |
Chronic Toxicity |
Acute Toxicity |
Human Health Criteria |
Aluminum |
742 |
1073 |
- |
Arsenic |
200 |
360 |
50 |
Benzene |
- |
- |
712.8 |
Cadmium |
1 |
4 |
168 |
Carbon
Tetrachloride |
- |
- |
44.2 |
Chlordane |
0.004 |
2.5 |
0.006 |
Chlorobenzene |
- |
- |
20 |
Chlorpyrifos |
0.041 |
0.083 |
- |
Chromium |
10 |
15 |
3365 |
Copper |
10 |
20 |
1000 |
Cyanide |
10 |
45 |
- |
4,4-DDT++ |
0.001 |
0.55 |
0.00559 |
Para-Dichlorobenzene |
- |
- |
2.6
mg/l |
3,3-Dichlorobenzidine |
- |
- |
0.2 |
1,2-Dichloroethane |
- |
- |
986 |
1,1-Dichloroethylene |
- |
- |
32 |
Dieldrin |
0.0019 |
2.1 |
0.0014 |
Dioxin
(2,3,7,8-TCDD) |
- |
- |
0.00014
ng/l |
Endosulfan |
0.15 |
0.3 |
2400 |
Endrin |
0.0023 |
0.18 |
8.1 |
Heptachlor |
0.0038 |
0.38 |
0.002 |
y-Hexachlorocyclopentadiene
(Lindane) |
0.33 |
4.1 |
0.63 |
Lead |
3 |
80 |
- |
Mercury |
0.05 |
2.5 |
0.15 |
Nickel |
150 |
1400 |
4584 |
Parathion |
0.013 |
0.065 |
- |
Pentachlorophenol
(PCP) |
(a) |
(a) |
82 |
Polychlorinated
Biphenyls (PCBs) |
0.014 |
2 |
0.0004 |
Polynuclear
Aromatic Hydrocarbons (PAHs) |
0.03 |
30 |
0.3 |
Phenols |
50 |
1000 |
300 |
Selenium |
70 |
100 |
- |
Silver |
0.35 |
4 |
- |
Toluene |
50 |
2500 |
300
mg/l |
Total
Residual Chlorine (TRC) |
10 |
20 |
- |
Toxaphene |
0.0002 |
0.73 |
0.0075 |
1,1,1-Trichloroethane |
- |
- |
173
mg/l |
Trichloroethylene
(TCE) |
80 |
4000 |
807 |
Vinyl
Chloride |
- |
- |
5250 |
Zinc |
100 |
110 |
5000 |
(a) Numerical
criteria are a function of pH using the equation: Criterion (mg/l = e[1.005(pH)-x], where
e =
2.71828 and xacute = 3.34 and xchronic = 3.80
Table 2. Criteria for ammonia nitrogen, for warm water streams and
lakes. Source: Iowa Administrative Code, Ch. 61, Water
Quality Standards, November 1990.
Temp °C |
pH |
6.5 |
7.0 |
7.2 |
7.4 |
7.6 |
7.8 |
8.0 |
8.2 |
8.4 |
8.6 |
8.8 |
9.0 |
1.0 |
Acute Chronic |
49.0 9.8 |
39.5 7.9 |
33.8 6.8 |
27.6 5.5 |
21.4 4.3 |
15.8 3.2 |
11.2 2.2 |
7.1 1.4 |
4.5 0.9 |
2.9 0.6 |
1.8 0.4 |
1.2 0.2 |
5.0 |
Acute Chronic |
46.4 9.3 |
37.4 7.5 |
32.1 6.4 |
26.2 5.2 |
20.3 4.1 |
15.0 3.0 |
10.6 2.1 |
6.8 1.4 |
4.3 0.9 |
2.8 0.6 |
1.8 0.4 |
1.2 0.2 |
10.0 |
Acute Chronic |
44.0 8.8 |
35.5 7.1 |
30.5 6.1 |
24.9 5.0 |
19.3 3.9 |
14.3 2.9 |
10.1 2.0 |
6.5 1.3 |
4.1 0.8 |
2.7 0.5 |
1.8 0.4 |
1.2 0.2 |
15.0 |
Acute Chronic |
42.3 8.5 |
34.1 6.8 |
29.3 5.9 |
24.0 4.8 |
18.6 3.7 |
13.8 2.8 |
9.8 2.0 |
6.3 1.3 |
4.1 0.8 |
2.7 0.5 |
1.8 0.4 |
1.2 0.2 |
20.0 |
Acute Chronic |
41.2 8.2 |
33.3 6.7 |
28.6 5.7 |
23.4 4.7 |
18.2 3.6 |
13.5 2.7 |
9.7 1.9 |
6.2 1.2 |
4.1 0.8 |
2.7 0.5 |
1.8 0.4 |
1.2 0.2 |
25.0 |
Acute Chronic |
40.7 8.1 |
32.9 6.6 |
28.3 5.7 |
23.2 4.6 |
18.1 3.6 |
13.5 2.7 |
9.7 1.9 |
6.3 1.3 |
4.2 0.8 |
2.7 0.5 |
1.8 0.4 |
1.2 0.2 |
30.0 |
Acute Chronic |
20.4 4.1 |
16.5 3.3 |
14.2 2.8 |
11.7 2.3 |
9.1 1.8 |
6.8 1.4 |
5.0 1.0 |
3.3 0.7 |
2.2 0.4 |
1.5 0.3 |
1.1 0.2 |
0.8 0.2 |
Table 3.
Substances of concern in lake water and sediment elutriate water. Substances of concern are shown in bold
italics.
|
Southwest
side of Little Lake at Ventura Marsh Outflow |
Northwest
Side of Little Lake (near Harbor Inn) |
North
Side of Little Lake |
Site
40 in Little Lake |
Ventura
Marsh |
|||||
Pollutant |
Water |
Elutriate |
Water |
Elutriate |
Water |
Elutriate |
Water |
Elutriate |
Water |
Elutriate |
Cadmium |
<0.001
mg/L |
<0.001
mg/L |
0.001 mg/L |
<0.001
mg/L |
<0.001
mg/L |
<0.001 mg/L |
<0.001 mg/L |
<0.001 mg/L |
<0.001 mg/L |
<0.001 mg/L |
Chromium |
<0.02
mg/L |
<0.02
mg/L |
0.03 mg/L |
<0.02
mg/L |
<0.02
mg/L |
<0.02 mg/L |
<0.02 mg/L |
<0.02 mg/L |
<0.02 mg/L |
<0.02 mg/L |
Copper |
<0.01
mg/L |
<0.01
mg/L |
0.03 mg/L |
<0.01
mg/L |
<0.01
mg/L |
0.03 mg/L |
<0.01 mg/L |
0.01 mg/L |
<0.01 mg/L |
<0.01 mg/L |
Lead |
0.02 mg/L |
<0.01
mg/L |
<0.01
mg/L |
<0.01
mg/L |
0.01 mg/L |
<0.01 mg/L |
<0.01 mg/L |
0.01 mg/L |
<0.01 mg/L |
<0.01 mg/L |
Zinc |
0.04
mg/L |
0.31 mg/L |
0.22 mg/L |
0.15 mg/L |
0.02
mg/L |
0.36 mg/L |
<0.02 mg/L |
0.39 mg/L |
<0.02 mg/L |
0.02 mg/L |