The water quality monitoring program began in 1984 and is ongoing. The program assesses the water quality by evaluating the levels of nutrients and closely related habitat impacts such as dissolved oxygen and water clarity. One of the main goals of the Chesapeake Bay restoration is to reduce the impacts of excess nutrients on the Bay and these measures provide some of the most direct linkages to management programs that are achieving this goal. The Chesapeake Bay Program jurisdictions have agreed to reduce nitrogen, phosphorus and sediment pollution to the Bay.
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://archive.chesapeakebay.net/pubs/cbwqdb2004_RB.PDF]>.
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]>.
The Quality Assurance Project Plan for the Maryland Department of Natural Resources Chesapeake Bay Water Quality Monitoring Program - Chemical and Physical Properties Component for the period July 1, 2009 - June 30, 2010 [<http://mddnr.chesapeakebay.net/eyesonthebay/documents/MD_DNR_MTQAPP09_Draft1.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 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) 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.
February 2009 - While sampling at station CB3.2, a barge passed, water quality meter readings were unstable. The cruise log noted that the switch-over from use of Hydrolab sondes to use of YSI sondes had occurred. Samples collected on 12 February were collected from small boats.
March 2009 - Sampling was completed as plannned with no unusual circumstances.
April 2009 - The water quality sonde conductivity sensor behaved erratically at station CB2.2. Surface and AP water samples at station CB5.2 were collected from a bucket.
May 2009 - A field log comment noted that there had been heavy rains, as much as four inches in some locations in the watershed, during the previous week. A H2S odor was reported in bottom samples collected a stations CB4.1C and CB3.3C. At station CB1.1 the pH sensor was slow to respond. Station CB3.2 5m and AP samples were collected from separate bottles.
June 2009 - The deck crew reported a H2S odor in bottom samples collected at stations CB4.1E, CB4.1C and CB3.3C. Values obtained using water quality data sonde 'Y' at stations CB5.3 and CB4.1E were described as 'erratic'.
July 2009 - July 14th Cruise log notes for stations CB4.3E, CB4.3C, CB4.2C, CB 4.2E, CB4.1C and CB3.3C mentioned that a H2S odor in bottom samples was observed. Beginning with station CB4.3C at 09:24 on July 14th, use of water quality sonde 'Y' was discontinued. Water quality readings for the remaining stations of the survey were obtained using sonde 'Z'. Dissolved oxygen readings at 1m at station CB4.2E were double checked. During July 27th and 28th at most stations sampled a H2S odor was observed.
August 2009 - H2S odors were reported at several stations on August 10th, 11th and 25th. Station CB3.3W 6m sonde readings were 'unstable' on 11 August.
September 2009 Sampling was completed as plannned with no unusual circumstances.
October 2009 - Field log comments for several stations mentioned that heavy rains had fallen in the October 10 - 14 period.
November 2009 - Station CB2.2 bottom and BP water samples were collected from the same bottle. Station CB3.1 surface and AP water samples were collected from the same bottle. Station CB3.2 surface and AP water samples were collected from the different bottles.
December 2009 Specific conductance readings at station CB3.1 3m depth were unstable.
Sampling-event and physical properties, nutrient and suspended solid data from twenty-one Chesapeake Bay Mainstem stations are included in the dataset.
Silica (SIF) samples were collected monthly, from the surface and above pycnocline layers, January through June 2009 at the Maryland DNR Phytoplankton sampling Program stations co-located with water quality program (CB1.1, CB2.2, CB3.3C, CB4.3C, CB5.2, TF2.3, RET2.2, LE2.2, TF1.5, TF1.7, LE1.1, ET5.1 and WT5.1). Silica samples were not collected at any stations July through December 2009.
January 2009 - Stations CB1.1, CB2.1, CB2.2, CB3.1 were not sampled due to ice concerns, steel hull restrictions were in effect above Swan Point.
May 2009 - Air temperature was not recorded at station CB5.3.
The Yellow Springs Instrument (YSI) 6000 data sondes and HydroLabs were maintained and calibrated before and after each cruise in accordance with manufacturer's 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. Tributary bottom equals total depth minus one meter (not rounded). 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, and 1.0 m above 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.
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 1.0 m above the bottom.
SECCHI DEPTH:
Water transparency was determined, to the nearest 0.1 m using a 20-cm standard Secchi disc lowered into the water column with a calibrated rope. Observations were made on the shady side of the sampling location.
PHOTOSYNTHETIC ACTIVE RADIATION (PAR):
PAR readings were taken in the field in order to calculate a light attenuation coefficient. PAR measurements were taken with a LICOR quantum meter (Model LI-1000 Data Logger) with an attached underwater probe (Model LI-192SA). The probe was a flat, upwardly-directed probe.
A vertical profile of light penetration was begun by taking an initial reading with the sensor just below the surface of the water (0.1 m). Subsequent readings were taken at either 0.25 m or 0.50 m intervals depending on the turbidity of the water column, (taking shallower readings in more turbid water). Depth readings were continued until a value less than ten percent (10%) of the surface reading was attained. Once the readings stabilized, at least five readings were allowed to flash on the instrument display before recording the data reading for a specific depth. The mean of the previous five readings that appeared on the instrument display were recorded in the data logger.
Light measurements made for each profile are log-scale regressed against depth to determine the compensation depth, i.e., the depth of penetration of one percent (1 %) of the surface PAR. The compensation depth is used in computing the integrated carbon production for that water column. When light profiles are not available, the Secchi disk depth is used to calculate the compensation depth. A regression has been made between the Secchi depth and the compensation depth for the same water column (for those stations where both Secchi data and LICOR data are taken). By using this regression, a compensation depth can be estimated from a Secchi depth.
University of Maryland's Chesapeake Biological Laboratory (CBL), Nutrient Analytical Services Laboratory (NASL) analyzed total dissolved nitrogen, particulate nitrogen, nitrite, nitrite + nitrate, ammonium, total dissolved phosphorus, particulate phosphorus, particulate inorganic phosphorus, orthophosphate, dissolved organic carbon, particulate carbon, total suspended solids, and volatile suspended solids.
Beginning in 2009, the NASL also performed chlorophyll analyses. Prior to 2009, chlorophyll analyses were performed by the Maryland Department of Mental Health and Hygiene.
Further information about laboratory analytical procedures may be obtained from the "Process_Contact".
Each month DNR Tawes Office and Field Office personnel conduct data QA/QC procedures. All of the water quality calibration "grab" sample data are plotted. Outliers and anomalous values are thoroughly researched. Staff members compare unusual values to historic values from the site and values from nearby sites. Weather events are considered, event logs are reviewed and CBL analytical laboratory staff members and DNR field staff members are consulted regarding possible legitimate causes for outlying values. In cases where values are not considered to be legitimate, they were masked in the published dataset with the approval of the field staff and the Quality Assurance Officer.
The data are contained in four related entities (tables): Station_Information, Monitoring_Event_Data, Water_Quality_Data and Light_Attenuation_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 entity Light_Attenuation_Data is comprised of the attributes: EVENT_ID, SOURCE, PROJECT, STATION, SAMPLE_DATE, SAMPLE_TIME, SAMPLE_REPLICATE_TYPE, DEPTH, EPAR_S, EPARU_Z, EPARD_Z, UNIT, METHOD, DETAILS, WATER_BODY, TOTAL_DEPTH, UPPER_PYCNOCLINE, and LOWER_PYCNOCLINE.
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 Shallow Water Quality Monitoring Program, for the period July 1, 2008 - June 30, 2009. [<http://mddnr.chesapeakebay.net/eyesonthebay/documents/SWM_QAPP_2008_draft2.pdf> ].