QUALITY ASSURANCE/QUALITY CONTROL
Maryland Department of Natural Resources followed specific procedures to ensure that the Tributary component of the Chesapeake Bay Water Quality Monitoring Program design was properly implemented and managed with sufficient accuracy, precision and detection limits. Accuracy (closeness to the true value) of collected data was controlled and assured by proper use, calibration and maintenance of both field and laboratory equipment for the measurement of physical and chemical parameters.
The procedures used to control and assure the accuracy of field measurements involved the calibration of field instruments, the verification of calibrations, and equipment maintenance. Most of the details of how data acquired with YSI sondes and Hydrolab sondes were quality assured and quality controlled are described in the process description elements in the Lineage portion of this metadata record.
Daily quality control checks which included the running of blanks and standards were used to control and assure laboratory accuracy.
Accuracy of Chesapeake Biological Laboratory, Nutrient Analytical Services Laboratory (CBL NASL) results was also assessed through DNR's participation in the Chesapeake Bay Coordinated Split Sample Program (CSSP) a split sampling program in which five laboratories involved in Chesapeake Bay monitoring analyze the coordinated split samples. CSSP was established in June 1989 to establish a measure of comparability between sampling and analytical operations for water quality monitoring throughout the Chesapeake Bay and its tributaries. DNR followed the protocols in the Chesapeake Bay Coordinated Split Sample Program Implementation Guidelines (EPA 1991) and its revisions. Split samples were collected quarterly. Results were analyzed by appropriate statistical methods to determine if results differed significantly among labs. If a difference occurred, discussions began regarding techniques and potential methods changes to resolve discrepancies.
ADDITIONAL COMMENTS
January 2018: When the dissolved oxygen sensor, used for water quality measurements at stations LE1.4, LE1.3, LE1.2, LE1.1, RET1.1, TF1.7, TF1.6 and TF1.5, was post calibrated, results were determined to be 0.47mg/l higher than the calibration standard. The water at station ET3.1 was seventy percent ice covered. Station ET4.2 bottom and below pycnocline water samples were collected from the same bottle. Pycnoclines did not exist at stations: EE2.1 and EE1.1 and the above pycnocline and below pycnocline samples were collected from 1/3 and 2/3 of total station water column depth.
February 2018: The 0.5m and 1.0m water samples at stations: LE1.4 were collected from the same bottle. Above and below pycnocline samples were collected from 1/3 and 2/3 of total water column depths at stations EE2.1, EE3.1 and EE3.2 due to absence of pycnoclines. Station EE1.1 bottom and below pycnocline water samples were collected from different bottles. Overnight showers occurred prior to sampling at stations WT7.1, WT8.1, WT8.2 and WT8.3.
March 2018: The 0.5m and 1.0m water samples at station LE1.4 were collected from a single bottle. Samples at stations EE2.1, EE3.1 and EE3.2 were collected at 1/3 and 2/3 total station depths because there were no pycnoclines. The below pycnocline sample at station ET4.2 should have been collected at the 10m depth. Verification of station ET4.2 9m depth conductivity was not possible. Lots of debris was observed at station ET2.3.
April 2018: The Secchi disk depth measurement at station TF1.3 exceeded the station total water column depth. Pycnoclines were not evident at stations RET2.4, ET5.2, EE1.1, EE2.1, EE3.1, EE3.2 and ET4.2 and above pycnocline and below pycnocline water samples were collected from 1/3 and 2/3 of station total depths. Rain drizzle was noted prior to sampling at stations EE2.2 and EE2.1. Scattered showers occurred during the day preceding sampling at stations WXT0001 and TF1.3. Station WIW0141 samples were collected from the ferry.
May 2018: The bridge at station MAT0078 was being power-washed during sampling operations. Secchi disk depth measurement at station TF1.3 was greater than the station total water column depth. As no pycnoclines existed in water columns at stations ET5.2, EE2.1, EE3.1 and EE3.2, samples were collected at 1/3 and 2/3 of station water column depths. Dissolved oxygen readings at station ET6.2 were double-checked. A tugboat passed over station ET6.2 prior to sample collection.
June 2018: The 0.5m and 1.0m water samples were obtained from water collected at the same depth. Morning rain showers occurred prior to station RET2.4 sampling. Water samples for station TF1.3 were collected at the park upstream of the bridge. Remarks about overnight rain showers were included in the field sheet comments for stations EE3.1, ET7.1, ET6.2 and EE3.0. Station ET5.2, EE3.2 and LE2.2 above pycnocline and below pycnocline samples were collected at 1/3 and 2/3 station total depths because there were no pycnoclines.
July 2018: Scattered rain showers fell during the morning of sample collections at stations LE1.1, LE1.2, LE1.3, LE1.4, RET1.1, TF1.5, TF1.6 and TF1.7. Hydrogen sulfide odors were noted in the water collected from the bottom and below pycnocline water bottles at station LE1.1 and the bottom bottle at station RET1.1. Above pycnocline and below pycnocline samples were collected at 1/3 and 2/3 of total water column depths, respectively, at stations RET2.4, EE1.1, EE2.1, ET4.2, ET5.2, EE3.1 and EE3.2, because there were no pycnoclines. Afternoon thunderstorms occurred the day before samples were collected at stations ET1.1, ET2.1, ET2.2 and ET2.3. Station WIW0141 samples were collected from the dock because the ferry was closed. Green flocs, possibly microcystis, were observed in station TF2.4 surface waters. The river was very green when samples were collected at station ET3.1.
August 2018: A Patuxent Cruise Report note observed “super nasty water” at station RET1.1. Pycnoclines were not present at stations EE2.1, EE3.1, EE3.2 and ET5.2 and above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of each station’s total station water column depth, respectively. Bottom water at station EE2.1 smelled of hydrogen sulfide. Dissolved oxygen results at 1m and 4m depths at station WT8.1 were re-checked with a second meter. Thunderstorms occurred during the night preceding sampling operations at stations ET1.1, ET2.1, ET2.2 and ET2.3. Samples for station ET3.1 were collected from pier B instead of pier A. Station ET3.1 waters were green.
September 2018: There was no pycnocline at station EE2.1, and above pycnocline and below pycnocline sample waters were collected from 1/3 and 2/3 of total station water column depth, respectively. Rain showers fell during the night prior to sample collection at stations LE1.1, LE1.2, LE1.3, LE1.4, RET1.1, TF1.5, TF1.6 and TF1.7.
October 2018: Pycnoclines were not extant at stations EE1.1, EE2.1, EE3.1, EE3.2, ET4.2, ET5.2, LE2.3 and RET2.4. Therefore, the above pycnocline and below pycnocline samples were collected from 1/3 and 2/3 of total water column depths, respectively, at each station.
November 2018: Snow was falling during sampling operations at station ET2.2. There were no pycnoclines at stations EE1.1, EE2.1, EE3.1, EE3.2, ET4.2, ET5.2, LE2.3 and RET2.4, and above pycnocline and below pycnocline samples were collected from 1/3 and 2/3 of total station water column depths, respectively. When Station ET10.1 was sampled, strong currents made it difficult to maintain the sampling pump and sonde array at the bottom depth. Station EE1.1 0.5m and 1m samples came from the same depth. Post-survey calibration tests of the conductivity sensor, used for station EE2.2 returned results 3,600 micro ohms/cm higher than the 24,280 micro ohms/cm standard. The water level at station PIS0033 was very high.
December 2018: When post-calibration tests were conducted on the sensor used to measure pH at stations TF1.0 and WXT0001, the results were outside of the acceptable range. Due to absence of pycnoclines at stations LE2.3, RET2.2 and RET2.4, at each station, above pycnocline and below pycnocline samples were collected from 1/3 and 2/3 of total water column depths, respectively. Ice was observed floating down river when station MON0528 was sampled. Skim ice was noted at station ET1.1 and skim ice on the edge was observed at station CAC0031. Bottom and below pycnocline water samples at station EE2.1 were collected from the same bottle.