Alkalinity

Water samples are collected in the field using a Kemmerer Sampler for laboratory analysis of alkalinity.  A 250-ml sample in a HDPE bottle is collected for analysis of alkalinity.  Care should be taken to miniimize sample agitation during collection.  Sample bottles are completely filled to minimize air trapped beneath the lid.  Each sample is placed in an ice chest in the field, and then stored at 4 degrees C in the laboratory refrigerator.  Samples are taken at both the hypolimnetic and epilimnetic levels of each lake.  Preferably, the analysis is completed within 1 day after the samples are collected.

Each alkalinity sample is analyzed according to the potentiometric titration to a preselected pH method (Section 2320 B in Standard Methods for the Examination of Water and Wastewater, 20th ed).  An Orion model 407A selective ion meter is used. The meter is calibrated against a Fisher calibration buffer (7.0 and 4.0) or equivalent prior to each two measurements.

Ammonia

Water samples are collected in the field using a Kemmerer Sampler for laboratory analysis of ammonia-nitrogen.  A 125-ml sample in a HDPE bottle is collected for analysis of ammonia-nitrogen.  The samples are acidified at the sampling site to a pH<2 by addition of a H₂SO₄ solution, placed in an ice chest in the field, and then stored at 4 degrees C in the laboratory refrigerator.  Samples are taken at both the hypolimnetic and epilimnetic levels of each lake.  The analysis is completed within 28 days after the samples are collected.

Each ammonia-nitrogen sample is analyzed by the alkaline phenol and hypochlorite method using segmented flow analysis on an Alpkem FLOW Solution Autoanalyzer Model 3570 (OI Analytical.  2000. Methology: Ammonia Nitrogen, USEPA by Segmented Flow Analysis, Publication 14910500, College Station, TX).  Calibration is conducted with at least five serial dilutions of a standard  ammonia-nitrogen solution and a solution blank.

Chlorophyll

a

Water samples are collected in the field using a Kemmerer Sampler for laboratory analysis of chlorophyll a.  A specific amount of lake water is filtered through a Whatman GF/F filter using a Nalgene PSF filter holder with reciever and a Nalgene hand operated vacuum pump.  The minimum amount of water to be filtered is determined by the Secchi disk measurement as follows:

 Secchi depth (m)         Volume of

                                  water (ml)

   < 0.3                              50

   > 0.3 to 0.5                   100

   > 0.5 to 0.75                 200

   > 0.75 to 1.0                 300

   > 1.0 to 2.0                   500

   > 2.0 to 3.0                   800

   > 3.0 to 5.0                 1000

   > 5.0                          1500

After filtration, the chlorophyll filter is folded and placed in a 50-ml opaque HDPE bottle with forceps.  The sample is then placed in an opaque ice chest in the field and later stored in the dark at <0 degrees C in the laboratory freezer until laboratory analysis - up to three weeks.

Chlorophyll a concentration is determined using the acetone extraction, grinding, and spectrophotometric method in Standard Methods for the Examination of Water and Wastewater, 20th ed (Section 10200 H).  A Varian model DMS-80 spectrophotometer is used for this analysis

Conductivity

In-situ measurements of conductivity are taken using a YSI Model 85 Oxygen, Conductivity, Salinity, and Temperature probe (manufactured by Yellow Spring Instrument, Co., Inc., Yellow Springs, Ohio).  The probe is slowly lowered into the lake and measurements are taken according to manufacturer's instructions at one-meter intervals.

Not applicable

Dissolved

Oxygen

(DO)

In-situ measurements of dissolved oxygen are taken using a YSI Model 85 Oxygen, Conductivity, Salinity, and Temperature probe (manufactured by Yellow Spring Instrument, Co., Inc., Yellow Springs, Ohio).  The probe is slowly lowered into the lake and measurements are taken according to manufacturer's instructions at one-meter intervals.

Not applicable

Indiana Trophic

State Index

(ITSI)

Not applicable

Results from water quality parameter analyses are used to calculate the ITSI for each lake and to better understand the limnology of the sampled lakes.  Indiana TSI scores are calculated from ten water quality parameters (total phosphorus, soluble phosphorus, organic nitrogen, nitrate, ammonia, dissolved oxygen, light penetration, light transmission, and total plankton ).  Eutrophy points are assigned according to the value of the measured parameter.  The eutrophy points assigned for each parameter are summed to give the total ITSI score.  The data are used to identify changes that may have occurred in the lakes since other analyses were done.

Nitrate+Nitrite

Water samples are collected in the field using a Kemmerer Sampler for laboratory analysis of nitrate-nitrogen.  A 125-ml sample in a HDPE bottle is collected for analysis of nitrate-nitrogen.  The samples are acidified at the sampling site to a pH<2 by addition of a H₂SO₄ solution, placed in an ice chest in the field, and then stored at 4 degrees C in the laboratory refrigerator.  Samples are taken at both the hypolimnetic and epilimnetic levels of each lake.  The analysis is completed within 28 days after the samples are collected.

Each nitrate-nitrogen sample is analyzed by the cadmium reduction method using segmented flow analysis on an Alpkem FLOW Solution Autoanalyzer Model 3570 (OI Analytical.  2000. Methology: Nitrate plus Nitrate Nitrogen and Nitrite Nitrogen, USEPA by Segmented Flow Analysis, Publication 14900500, College Station, TX).  Calibration is conducted with at least five serial dilutions of a standard nitrate-nitrogen solution and a solution blank.

Light Transmission

(% at 3 ft depth)

Percentage of light transmitted is determined by the use of a Beckman Industries (Irvine, CA) EV3 Enviroeye light meter.  A measurement is taken at three feet (as specified by the IDEM Eutrophication Index) and the depth at which one percent transmittance is reached will also be recorded.

Not applicable

Percent

blue-green

algae

Not applicable 

Percent blue-green algae is determined from the data that are recorded using the methods to collect total plankton.

pH

Water samples are collected in the field using a Kemmerer Sampler for laboratory analysis of pH.  A 250-ml sample in a HDPE bottle is collected for analysis of pH.  Care should be taken to miniimize sample agitation during collection.  Sample bottles are completely filled to minimize air trapped beneath the lid.  Each sample is placed in an ice chest in the field, and then stored at 4 degrees C in the laboratory refrigerator.  Samples are taken at both the hypolimnetic and epilimnetic levels of each lake.  Preferably, the analysis is completed within 1 day after the samples are collected.

An Orion 91-02 pH probe is used. The probe is calibrated against a Fisher calibration buffer (7.0 and 4.0) or equivalent prior to each two measurements.  

Soluble Reactive

Phosphorus (SRP)

Water samples are collected in the field using a Kemmerer Sampler for laboratory analysis of soluble reactive phosphorus.  A filtered sample of 125 ml in an acid-washed glass bottle is taken for analysis of soluble phosphorus.  The sample is filtered on site (using Whatman GF/C filters in a Buchner funnel, side-arm flask, and a Nalgene hand-operated vacuum pump) and then placed in an ice chest in the field, and stored at 4 degrees C in the laboratory refrigerator.  Samples are taken at both the hypolimnetic and epilimnetic levels of each lake tested.  The analysis is completed within 48 hours after the samples are collected.

Soluble reactive phosphorus samples are analyzed by use of the ascorbic acid method of colorimetry listed in Standard Methods for the Examination of Water and Wastewater, 20th ed (Section 4500-P E).  A Varian model DMS-80 spectrophotometer is used in this analysis.  Calibration is conducted with at least five serial dilutions of a standard phosphate solution and a solution blank. 

Total

Kjeldahl

Nitrogen

Water samples are collected in the field using a Kemmerer Sampler for laboratory analysis of total Kjeldahl nitrogen.  A 125-ml sample in a HDPE bottle is collected for analysis of total Kjeldahl nitrogen.  The samples are acidified at the sampling site to a pH<2 by addition of a H₂SO₄ solution, placed in an ice chest in the field, and then stored at 4 degrees C in the laboratory refrigerator.  Samples are taken at both the hypolimnetic and epilimnetic levels of each lake.  The analysis is completed within 28 days after the samples are collected.

A 50-ml aliquot of sample is analyzed for total Kjeldahl nitrogen by digestion (EPA Method 351.2 Determination of Total Kjeldahl Nitrogen by Semi-Automated Colorimetry, Revision 2.0, August 1993; 7.3 Note 1: alternate mercury-free digestion solution) on LabConCo Micro-Kjeldahl model 60300 digesters.  The final ammonia measurement is determined by the salicylate and hypochlorite method using segmented flow analysis on an Alpkem Flow Solution Autoanalyzer Model 3570 (OI Analytical.  2000. Methology: Total Kjeldahl Nitrogen (TKN), USEPA by Segmented Flow Analysis, Publication 14920500, College Station, TX).  Calibration is conducted with at least five serial dilutions of a standard ammonia-nitrogen solution and a solution blank.

Total

Plankton

Total plankton is measured by lowering a 63-micron nylon screen conical tow net with a 61-micron stainless steel mesh bucket (manufactured by Wildlife Supply Company, Saginaw, MI) for a vertical tow below the sampling site.  The tow net is lowered to the one percent light level, which should be sufficient to obtain a representative sample of the plankton in the water column.  The tow net is brought to the surface by a hand over hand method, maintaining a constant speed of 0.5 meters/second.  After the tow net is brought to the surface, the sample is poured into a 250-ml opaque, high-density polyethylene (HDPE) bottle and preserved with Lugol's solution (Section 10200 B in Standard Methods for the Examination of Water and Wastewater, 20th ed).  Preserved samples are placed in an ice chest in the field and later transferred to a laboratory refridgerator until analysis.  The Lugol's preservative provides excellent preservation of plankton cells for at least one year.  Our plankton samples are counted within one year of collection.

Plankton genera are identified and enumerated using Sedgewick-Rafter counting cells (Section 10200 F, Standard methods for the Examination of Water and Wastewater, 20th ed).  For each sample, fifteen fields are counted at 150x magnification.  Identification and genera names are according to Prescott (1982), Ward and Whipple (1959), or Whitford and Schumacher (1984).

Total

Phosphorus

Water samples are collected in the field using a Kemmerer Sampler for laboratory analysis of total phosphorus.  A 125-ml sample in an acid-washed, glass sampling bottle is collected for analysis of total phosphorus.  The samples are acidified, placed in an ice chest in the field, and then stored at 4 degrees C in the laboratory refrigerator.  Samples are taken at both the hypolimnetic and epilimnetic levels of each lake.  The analysis is completed within 28 days after the samples are collected.

A 50-ml aliquot of sample is analyzed for total phosphorus by sulfuric acid-nitric acid digestion (Standard Methods for the Examination of Water and Wastewater, 20th ed, Section 4500-P B) on LabConCo Micro-Kjeldahl model 60300 digesters.  The final phosphorus measurement is determined by the ascorbic acid method of colorimetry listed in Standard Methods for the Examination of Water and Wastewater, 20th ed (Section 4500-P E).  A Varian model DMS-80 spectrophotometer is used in this analysis.  Calibration is conducted with at least five serial dilutions of a standard phosphate solution and a solution blank.

Total

Suspended

Solids

(TSS)

Water samples are collected in the field using a Kemmerer Sampler for laboratory analysis of total suspended solids.  A 1000-ml sample in a HDPE bottle is collected for analysis of total suspended solids.  The samples are then placed in an ice chest in the field, and then stored at 4 degrees C in the laboratory refrigerator.  The analysis is completed within 7 days after the samples are collected.

Total suspended solids is determined using the drying methods from Standard Methods for the Examination of Water and Wastewater, 20^th ed, Section 2540-D.  An American convection constant temperature drying oven heated at 103-105 degrees C is used to dry the filtered samples in Gooch crucibles. 

Transparency

Secchi disk transparency is measured using a conventional black and white eight-inch diameter disk attached to a rope graduated in tenths of meters.  The disk is lowered into the water until it is no longer visible.  It is then lowered some more and raised until it again becomes visible.  The midpoint between these two measurements is recorded as the Secchi disk depth. 

Not applicable

Water

Temperature

In-situ measurements of temperature are taken using a YSI Model 85 Oxygen, Conductivity, Salinity, and Temperature probe (manufactured by Yellow Spring Instrument, Co., Inc., Yellow Springs, Ohio).  The probe is slowly lowered into the lake and measurements are taken according to manufacturer's instructions at one-meter intervals.

Not applicable