BASIN: COB Drinking Water Monitoring Program

	City of Boulder/USGS Water Quality Monitoring
	City of Boulder Drinking Water Source Monitoring Program

The Drinking Water Program, Water Quality and Environmental Services, City of Boulder, conducts sampling of waters that are sources of drinking water for the City of Boulder. These samples are collected to characterize the quality of water used by the City of Boulder. This characterization includes assessing seasonal trends, detecting any possible contaminants that may have entered the water, and identifying the source of any contaminants. The Drinking Water Program collects monthly water quality samples from locations such as the Lakewood Reservoir, Barker Reservoir, Middle Boulder Creek, and Boulder Reservoir.

Source Water Quality Sampling Procedures

Sample Bottles:

TOC bottles are obtained from the USGS, where the bottles are washed with hot soapy water, rinsed with tap and distilled water, and burned for 8 hours at 250 degrees C. For the remaining bottles, each set of sample bottles is cleaned at the drinking water laboratory and reused for one particular sample site. After sampling, sample bottles are rinsed with tap water immediately after the sample has been analyzed. All sample bottles except those used for chlorophyll, metals, and bacteria are soaked for at least one hour in a 5% hydrochloric acid (HCl) bath. These bottles are then rinsed twice with tap water and twice with deionized water and allowed to air dry. Chlorophyll a bottles are rinsed with tap water only and allowed to air dry. Metals bottles are soaked in a 3% nitric acid (HNO₃) bath for at least one hour. Metals bottles are than rinsed in the same manner as the HCl-washed bottles. The day prior to sampling, all sample bottles except those used for bacteria are half-filled with deionized water and packed in sealed ziploc bags.

Sample Collection and Treatment:

All samples except Nederland effluent and samples from the water treatment plant taps are composite samples. Streams samples are vertically-, horizontally-, and time-composited. HCl-washed sample churns are used for compositing samples. All sample bottles are filled from the same aliquot of water. Reservoir top samples are composited from the photic zone using a Van Dorn instrument. Samples are repacked in the original ziploc bag and placed in coolers containing ice. Samples requiring filtration are filtered immediately upon arrival back at the lab. Samples are then acid-preserved and/or refrigerated, as required.

One replicate sample is collected for each sampling event. For field blanks, laboratory millipore water is transported to the field. Clean field equipment is used to fill a clean churn with this blank water. All field blank bottles are then filled from this blank water churn.

Field Parameters:

Water Temperature is analyzed with a YSI 600XL multi probe. The temperature probe is checked annually.

Dissolved Oxygen is analyzed with a YSI 600XL multi probe. Calibrations are conducted in the field at the sample site with a moist-air saturated bottle.

Specific Conductance is analyzed with a YSI 600XL multi probe. The probe is calibrated in the drinking water laboratory the day of sampling. A potassium chloride solution of 1412 micromhos/cm at 25° C is used in the calibration. Standards are replaced at least monthly.

pH is analyzed with a YSI 600XL multi probe. The probe is calibrated with pH 7 and 10 buffers in the drinking water laboratory the day of sampling. Buffers are replaced at least monthly.

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BASIN is funded through the US EPA EMPACT Program