Sampling Methods Water Quality Monitoring

Recruitment and Training of Volunteers

The Choctawhatchee Basin Alliance training goal is to maintain qualified citizen monitors on 145 sampling sites located within the Choctawhatchee Bay and all the coastal dune lakes in Walton County. CBA staff conducts approximately 25 training sessions per year to maintain over 65 active volunteers in the CBA water monitoring program. If you are interested in participating in this program, please visit the Volunteer Opportunities section of our website to find out where we currently need volunteers. Citizen volunteers are instructed by professional staff from CBA on the proper procedures for collecting surface (0.5 m) water samples and determining water clarity as measured by a Secchi disc. Volunteers are also trained to use a Hydrolab Quanta Water Quality Monitoring System provided by CBA to record surface and bottom measurements of temperature (°F), dissolved oxygen (mg/L), pH, salinity (ppt), dissolved oxygen saturation (%), and turbidity (NTU). Citizens are usually instructed on their waterbody during a two to four hour training session, which includes the selection and/or identification of sampling stations and water sampling procedures for both the Florida LAKEWACH Program and the CBA hydrolab. After receiving instructions, citizens are expected to sample their water body once each month. Volunteers are required to contact CBA monthly to schedule their sampling date to ensure availability of the Hydrolab Quanta Water Quality Monitoring System and to coordinate the pick-up and return of sampling equipment. When a volunteer was unable to sample, CBA staff collected the water samples. All volunteers are given sampling materials and booklets describing the water quality sampling procedures for future reference.

Field and Laboratory Procedures On each sampling date, citizen volunteers use their own boats or dedicated CBA watercraft to collect surface and bottom readings as well as surface water samples from three to ten open-water locations. Sometimes large water bodies are split into smaller areas, and each smaller area of the large water body is then sampled monthly by different citizen volunteers. For example, Western Lake in Walton County has a surface area of 220 acres (Shafer et al. 1986). Western Lake was split into three smaller areas for sampling by volunteers: Western, Western Northeast, and Grayton. Western’s three sampling stations are located south of the 30A bridge, Western Northeast’s three sampling locations are located on the north side of the 30A bridge, and Grayton’s three sampling stations are located in the west basin around the Grayton subdivision. CBA water monitoring efforts by citizen volunteers are a part of the statewide effort of the Florida LAKEWATCH Program. The Florida LAKEWATCH Program is run through the University of Florida’s Institute of Food and Agricultural Sciences’ Department of Fisheries. Surface samples for total phosphorus (µg/L), total nitrogen (µg/L), color (Pt-CO Units) and specific conductance (µS/cm @25°C) are collected at lake sampling stations in 250-ml, acid-cleaned, triple-rinsed Nalgene bottles and at bay sampling stations in 500-ml, acid-cleaned, triple-rinsed Nalgene bottles. Citizens also measure water clarity at each sampling location with a Secchi disc and collect additional surface water at each location in tap-water rinsed plastic jugs. Volunteers also use a Hydrolab Quanta Water Quality Monitoring System provided by CBA to record the following parameters at the surface and bottom of each sampling station: temperature (°F), dissolved oxygen (mg/L), pH, salinity (ppt), dissolved oxygen saturation (%), and turbidity (NTU). Upon returning to their residences, volunteers place the 250-ml or 500-ml Nalgene bottles in a freezer. To estimate the concentration of planktonic algae at each sampling station, volunteers filter a measured volume of water taken from the plastic jugs through a Gelman Type A-E glass fiber filter. Filters are then stored over silica gel desiccant and frozen. Water samples and the glass fiber filters are stored frozen at the homes of the citizen volunteers or at one of two LAKEWATCH collection centers located in Okaloosa and Walton Counties for one to four months. All frozen samples along with Secchi disc information are then delivered by Florida LAKEWATCH staff to the Department of Fisheries and Aquatic Science's water quality laboratory. All samples and filters are analyzed for total phosphorus, total nitrogen and chlorophyll concentrations monthly. Color is run quarterly on composite water samples for all lakes. Color and specific conductance (µS/cm @ 25°C) are run quarterly on bay stations.

At the laboratory, total phosphorus concentrations (µg/L) are determined using the procedures of Murphy and Riley (1962) with a persulfate digestion (Menzel and Corwin 1965). Total nitrogen concentrations (µg/L) for all lake samples are determined by oxidizing water samples with persulfate and determining nitrate-nitrogen with second derivative spectroscopy (D’Elia et al. 1977; Simal et al. 1985; Wollin 1987). A total nitrogen equivalency study of nitrogen in surface waters demonstrated that this method is a suitable substitute for the standard USEPA method involving the sum of nitrate-nitrogen and Kjeldahl-nitrogen as measured with an automated analyzer (Sylvia S. Labie, Administrator Florida Department of Environmental Regulation Quality Assurance Section, 1991). Total nitrogen concentrations (µg/L) for bay samples are determined by oxidizing water samples with persulfate and determining nitrate-nitrogen with an autoanalyzer, (Method 4500-NO3-F ; APHA 1992). Chlorophyll concentrations (µg/L) are determined spectrophotometrically (Method 10200 H; APHA 1992) following pigment extraction with ethanol (Sartory and Grobbelaar 1984). Specific conductance (µS/cm @ 25°C) is measured using a Yellow Springs Instrument Model 35 conductance meter. Color (Pt-Co Units) is determined by spectroscopy (Bowling et al. 1986).