The information is integrated with data from other Bay water quality stations and living resources monitoring projects and used to understand linkages, temporal variation and long-term trends.
Water quality data are used to refine, calibrate and validate Chesapeake Bay ecological models. The models are used to develop and assess water quality criteria with the goal of removing the Chesapeake Bay and its tidal rivers from the list of impaired waters.
Data users who desire very detailed information about Water Quality Monitoring data-definition, sampling-procedures and data-processing are encouraged to refer to the two documents listed below. The documents may be obtained from the Chesapeake Bay Program Office.
Water Quality Database - Database Design and Data Dictionary Prepared For: U.S. Environmental Protection Agency, Region III, Chesapeake Bay Program Office, January 2004. <http://www.chesapeakebay.net/pubs/cbwqdb2004_RB.PDF>
Quality Assurance Project Plan for the Maryland Department of Natural Resources Chesapeake Bay Water Quality Monitoring Program for the period July 1, 2008 - June 30, 2009 <http://mddnr.chesapeakebay.net/eyesonthebay/documents/MainStemTributaries2008-2009QAPP.pdf>
The project was made possible with funding provided by The State of Maryland, the United States Environmental Protection Agency Chesapeake Bay Program, and the National Atmospheric and Oceanic Administration Chesapeake Bay Program Office.
The procedures 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 Hydrolabs 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) and Maryland Department of Health and Mental Hygiene Environmental Chemistry Division (DHMH ECD) laboratory 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.
Hydrolab Meter Z's circulator did not work properly during the March 21 cruise. The dissolved oxygen probe was calibrated, checked, and post-calibrated correctly, however, the circulator motor was partially seized and the impeller was not spinning at the correct rpms. A standard Clark Polaragraphic dissolved oxygen probe requires a flow of 1.0 feet/sec of sample water across the membrane surface. Thus, dissolved oxygen data from Meter Z should not be used for statistical analyses.
Post calibration of HydroLab Meter D for dissolved oxygen during the October cruise on 10/22/08 resulted in a dissolved oxygen reading of 15.34 mg/L and a calculated reading of 9.07 mg/L. As such, dissolved oxygen data collected the day before, 10/21/08, was flagged as questionable. Zero point for conductivity on HydroLab Meter D was reading 12.8, calibration check at 24820 read 24882 on 10/22/08.
Sampling-event and physical properties, nutrient and suspended solid data from 22 Chesapeake Bay Mainstem stations are included in the dataset.
Fieldwork for this period commenced on January 15, 2008 with all samples collected on the January Cruise, January 15-17.
The February cruise, scheduled for February 12-13 was affected by weather and thus sampling was conducted on the 12th, 18th, and 19th of February. Stations CB5.3, LE2.3, CB5.2, CB5.1, CB4.4, along with station CB4.3C were sampled on the 12th during rough seas with ice build up on rigging and equipment. Sampling recommenced on the 18th and included tributary and Baltimore Harbor sampling along with station CB3.2, with the remainder of the upper Bay stations sampled on the 19th. Split samples were collected from station CB4.4 on February 12.
Sampling was scheduled for March 17-19, however, small craft warnings on March 17 resulted in sampling being postponed until March 18 and with bad weather predicted for March 19 and along with mechanical problems with vessel, sampling was put off until March 21. In order to maximize Main Bay sampling in the same week it was decided to drop flank stations and continue up the Bay on March 18. Phytoplankton samples were also collected for Morgan State University.
All samples were collected on the first April cruise, April 14-16. During this cruise Morgan State University phytoplankton samples and surface phytoplankton samples for Oxford Cooperative Laboratory were also collected. All samples were collected on the second April cruise, April 28-30 with phytoplankton samples collected for Morgan State University.
All samples were collected on the first May cruise, May 14, 15, and 16. The cruise was postponed for two days due to high winds and rough seas on May 12 and 13. Multi-lab split samples were collected from station CB4.4 on the first sampling day and phytoplankton samples for Morgan State University were also collected during the first cruise. During the second May cruise samples were collected on May 27 and 29. The main Bay was too rough to sample on the 28th so sampling was rescheduled for the 29th and flank stations were dropped due to time constraints. Phytoplankton samples for Morgan State University were also collected.
All samples were collected during the first June cruise, June 9-11 and phytoplankton samples were collected for Morgan State University. The second June cruise was June 23-25 with the first detection of hydrogen sulfide (measured by Hach kit) at stations LE2.3, CB4.3E, CB4.3C, CB4.2C, CB4.1E, CB4.1C, and CB3.3C. Phytoplankton samples were also collected for Morgan State University during the second June cruise.
All samples were collected on the first July cruise with phytoplankton samples collected for Morgan State University and Vibrio samples collected for Oxford Laboratory at surface samples. Hydrogen sulfide (measured by Hach kit) was recorded in below pycnocline and bottom samples at six mid-Bay stations, and stations CB4.3E and CB4.1E. All samples were collected during the second July cruise, July 21-23 with phytoplankton samples collected for Morgan State University.
All samples were collected during the first August cruise, August 11-13. Morgan State University phytoplankton samples were also collected and a multi-lab split sample was collected at station CB4.4 on August 11. During the August 13 cruise the crew was short of hands and thus Hach kits were not done for hydrogen sulfide. All samples were collected on the second August cruise, August 25-27 and Morgan State University phytoplankton samples were collected.
All samples were collected on the September cruise, September 15-18 and Morgan State University phytoplankton samples were collected. The odor of hydrogen sulfide was detected at only one station (CB4.1C) but no Hach kit measurements were done.
All samples were collected on the October cruise, October 20-22. Morgan State University phytoplankton samples were collected and Vibrio samples were also collected for Oxford Laboratory at surface samples. Post calibration checks of dissolved oxygen on October 22 were outside lines and dissolved oxygen data collected on the 21st was flagged as questionable.
Stations CB4.2C and CB4.1C were not sampled during the November cruise (November 17-19) due to rough seas. A multiple lab split sample was collected at station CB4.4 November 17 at 1330. Duplicate chlorophyll pad for Chesapeake Biological Laboratory comparison was done at all stations.
All samples were collected on the December cruise, December 16-18. Morgan State University phytoplankton samples were collected as were duplicate chlorophyll samples for Chesapeake Biological Laboratory. Extra chlorophyll samples were treated with MgCO3.
Hydrolab sensors were calibrated as outlined in the Work/Quality Assurance Project Plan and documented in log books that accompany each instrument. The practice of collecting samples for routine field splits of grab samples was continued in order to track the precision of the chemical analysis scheme from collection through processing, storage and chemical analysis.
The University of Maryland's Chesapeake Biological Laboratory continued to provide chemical analysis of grab samples for nitrogen, phosphorus, carbon, silica and total suspended solids for the Mainstem Water Quality Monitoring Program.
The Yellow Springs Instrument (YSI) 6000 data sondes and HydroLabs were maintained and calibrated before and after each cruise in accordance with manufacturers’ recommendations.
HYDROLAB PROFILE SAMPLING PROTOCOLS:
A profile of temperature, specific conductance, dissolved oxygen, and pH was obtained from the water column at 0.5 m, 1.0 m, 2.0 m and 3.0 m depth intervals below the surface. Thereafter readings were taken at 2.0 m intervals and at the bottom. Mainstem bottom equals total depth minus one meter, rounded to a whole meter. If the change in dissolved oxygen exceeded 1.0 mg/L or if the change in specific conductance equaled or exceeded 1,000 micromhos/cm over any 2.0 m interval, readings were taken at 1.0 m intervals between these two readings. For total depths less than or equal to 10.0 m, readings were taken at 1.0 m intervals.
GRAB SAMPLING DEPTH PROTOCOLS:
At stations where two depths are sampled collections were taken at 0.5 m below the surface, 1.0 m above the bottom to nearest 1.0 m that was at least one full meter from the bottom. If station total depth was greater than 1.5 m, a bottom sample was also taken at 0.5 m. Great caution was exercised when taking bottom samples; if disturbed bottom samples appeared to have been included in a sample, the station was resample after sediments had settled or a sample was taken slightly higher in the water column.
At stations where 4 depths were sampled and a pycnocline exists, collections were taken at 0.5 m below the surface, 1.5 m above upper boundary of pycnocline, 1.5 m below lower boundary of pycnocline, and 1.0 m above bottom to nearest 1.0 m that was at least one full m from the bottom.
At stations where 4 depths were sampled and there was no discernable pycnocline, samples were taken at 0.5 m below the surface, at closest profile depth one third the distance from the surface to the bottom, at closest profile depth two thirds the distance from the surface to the bottom, and 1. m above the bottom to the nearest 1.0 m that was at least one full meter from the bottom.
HYDROGEN SULFIDE PROTOCOLS:
At mainstem stations when there was an order of hydrogen sulfide present in bottom samples or below the pycnocline samples, a Hach Hydrogen Sulfide Test Kit (Model HS-6) test was performed for the presence of hydrogen sulfide.
SECCHI DEPTH:
Water transparency was determined, to the nearest 0.1 m using a 20-cm standard Secchi disc lowered into the water column wit a calibrated rope. Observations were made on the shady side of the boat.
Further information about laboratory analytical procedures may be obtained from the "Process_Contact".
Further information about laboratory analytical procedures may be obtained from the "Process_Contact".
The data are contained in three related entities (tables): Station_Information, Monitoring_Event_Data, Water_Quality_Data. Each table contains attributes (fields).
The entity Station_Information is comprised of the attributes: STATION, DESCRIPTION, WATER_BODY, CBP_BASIN, TS_BASIN, BASIN, CBSEG_2003, CBSEG_2003_DESCRIPTION, HUC8, CATALOGING_UNIT_DESCRIPTION, HUC11, WATERSHED, FIPS, STATE, COUNTY/CITY, FALL_LINE, LATITUDE, LONGITUDE, LL_DATUM, UTM_X and UTM_Y.
The entity Monitoring_Event_Data is comprised of the attributes: EVENT_ID, SOURCE, AGENCY, PROGRAM, PROJECT, STATION, EVENT_START_DATE, EVENT_START_TIME, CRUISE, TOTAL_DEPTH, UPPER_PYCNOCLINE, LOWER_PYCNOCLINE, AIR_TEMP, WIND_SPEED, WIND_DIRECTION, PRECIP_TYPE, TIDE_STAGE, WAVE_HEIGHT, CLOUD_COVER, GAGE_HEIGHT, PRESSURE, FLOW_STAGE, DETAILS and WATER_BODY.
The entity Water_Quality_Data is comprised of the attributes: EVENT_ID, SOURCE, PROJECT, STATION, SAMPLE_DATE, SAMPLE_TIME, DEPTH, LAYER, SAMPLE_TYPE, SAMPLE_ID, PARAMETER, QUALIFIER, VALUE, UNIT, METHOD, LAB, PROBLEM, DETAILS, TOTAL_DEPTH, UPPER_PYCNOCLINE, LOWER_PYCNOCLINE, LAT, and LONG.
The most current version of the Water Quality Data Dictionary - Online may be found at: [<http://archive.chesapeakebay.net/data/data_dict.cfm?DB_CODE=CBP_WQDB> ].
Quality Assurance Project Plan for the Maryland Department of Natural Resources, Chesapeake Bay Water Quality Monitoring Program, for the period July 1, 2008 - June 30, 2009. [<http://mddnr.chesapeakebay.net/eyesonthebay/documents/MainstemTributaries2008-2009QAPP.pdf>]
Data are available though the Chesapeake Bay Programs CIMS data hub. Select Water Quality Database (1984-Present). Access the data by following web site (see network resource name) instructions.