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.
Sampling-event and physical properties, nutrient and suspended solid data from 72 Chesapeake Bay Tributary stations are included in the dataset.
At station ET7.1 on January 15, 2008 Secchi depth was not measured and there was no bottom sample. Sampling was conducted from Ferry.
At stations TF1.0 and TF2.0 salinity was not measured on January 10, 2008.
Bottom sample was not collected at station ET2.3 on February 19, 2008 due to rough conditions.
Secchi depth was not measured at stations ET5.1 and ET5.2 on February 11, 2008.
Photosynthetic active radiation (par)was not measured at stations LE1.1, LE1.2, LE1.3, LE1.4, TF1.6, and TF1.7 on February 2, 2008.
Secchi depth was not measured at station XGG8251 on February 11, 2008.
Secchi depth was not measured at station TF1.3 on March 3, 2008; sample was collected from bridge.
Photosynthetic active radiation was not measured at stations CB5.1W, and LE1.4 on April 7 and April 16 2008 due to rough conditions.
Photosynthetic active radiation was not measured at stations CB5.1W, LE1.1, LE1.2, LE1.3, LE1.4, RET1.1, TF1.5, TF1.6, and TF1.7 on May 5 and April 16 2008 due to equipment failure.
Secchi depth and total depth was not measured at station TF1.3 on July 2, 2008.
Secchi depth was not recorded at station WXT0001 on August 4, 2008.
Secchi depth was not recorded at station WT7.1 on October 23, 2008.
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. 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. 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 wit a calibrated rope. Observations were made on the shady side of the boat.
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.
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.