Metadata: Identification_Information: Citation: Citation_Information: Originator: Maryland Department of Natural Resources (MD DNR), Resource Assessment Service Publication_Date: 20240501 Title: MD Dept. of Natural Resources, Chesapeake Bay Mainstem Water Quality Monitoring 2024 Geospatial_Data_Presentation_Form: Spatial dataset Online_Linkage: Description: Abstract: The physical/chemical component of the Maryland Chesapeake Bay Water Quality Monitoring Program consists of data collected at twenty-two stations located in Maryland's Chesapeake Bay mainstem. In total, fifteen samplings were completed in the period of 23-Jan-2024 through 4-Dec-2024. Planned sampling was conducted twice monthly in June, July, August of 2024, and once monthly during January, February, March, April, May, September, October, November, and December. Sampling during the second July cruise was limited to physical measurements only, collected to better assess dissolved oxygen levels in the mainstem deep waters. No samples were collected January, February, or December at eastern and western transect stations, resulting in only nine mainstem flanking station samplings during year 2024. 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. Purpose: The Maryland Department of Natural Resources Chesapeake Bay Water Quality Monitoring Program is part of a cooperative effort between the Federal government and State and local governments in the Chesapeake Bay watershed to assess the status and trends of nutrient and sediment concentrations in Maryland's Chesapeake Bay mainstem. 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. Supplemental_Information: The target audiences for this information include Resource Managers, Technical/Scientific Users, Government, Educators, Students, and the General Public. Data users who desire very detailed information about Water Quality Monitoring data definition, sampling procedures, and data processing are encouraged to refer to the 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. . An updated version of the data dictionary is a Chesapeake Bay Program work in progress. Guide to Using Chesapeake Bay Program Water Quality Monitoring Data, EPA 903-R-12-001, February 2012, CBP/TRS 304-12 . Methods and Quality Assurance for Chesapeake Bay Water Quality Monitoring Programs. Chesapeake Bay Program, May 2017, CBP/TRS-319-17 . The Quality Assurance Project Plan for the Maryland Department of Natural Resources Chesapeake Bay Mainstem and Tributary Water Quality Monitoring Program - Chemical and Physical Properties Component, June 2023 . Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 20240123 Ending_Date: 20241204 Currentness_Reference: Ground Condition Status: Progress: Complete Maintenance_and_Update_Frequency: As needed Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -80.53758 East_Bounding_Coordinate: -75.0405 North_Bounding_Coordinate: 39.7425 South_Bounding_Coordinate: 37.8713 Keywords: Theme: Theme_Keyword_Thesaurus: Global Change Master Directory (GCMD). 2025. GCMD Keywords, Version 21 Greenbelt, MD: Earth Science Data and Information System, Earth Science Projects Division, Goddard Space Flight Center (GSFC) National Aeronautics and Space Administration (NASA). URL (GCMD Keyword Forum Page): . Theme_Keyword: EARTH SCIENCE>BIOSPHERE>ECOSYSTEMS>MARINE ECOSYSTEMS>ESTUARY Theme_Keyword: EARTH SCIENCE>BIOSPHERE>ECOLOGICAL DYNAMICS>ECOSYSTEM FUNCTIONS>NUTRIENT CYCLING Theme_Keyword: EARTH SCIENCE>BIOSPHERE>ECOLOGICAL DYNAMICS>ECOSYSTEM FUNCTIONS>PRIMARY PRODUCTION Theme_Keyword: EARTH SCIENCE>OCEANS>SALINITY/DENSITY>PYCNOCLINE Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>SURFACE WATER>SURFACE WATER PROCESSES/MEASUREMENTS>WATER DEPTH Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>WATER CHARACTERISTICS>CHLOROPHYLL CONCENTRATIONS Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>WATER CHARACTERISTICS>CONDUCTIVITY Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>GASES>DISSOLVED NITROGEN Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>GASES>DISSOLVED OXYGEN Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>WATER CHARACTERISTICS>EUTROPHICATION Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>WATER CHARACTERISTICS>LIGHT TRANSMISSION Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>NUTRIENTS>NITROGEN Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>NUTRIENTS>NITROGEN COMPOUNDS Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>WATER CHARACTERISTICS>NITROGEN COMPOUNDS Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>WATER CHARACTERISTICS>pH Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>NUTRIENTS>PHOSPHOROUS Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>WATER CHARACTERISTICS>PHOSPHOROUS COMPOUNDS Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>WATER CHARACTERISTICS>SALINE CONCENTRATION Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>SOLIDS>SUSPENDED SOLIDS Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>SOLIDS>TOTAL DISSOLVED SOLIDS Theme_Keyword: EARTH SCIENCE>TERRESTRIAL HYDROSPHERE>WATER QUALITY/WATER CHEMISTRY>WATER CHARACTERISTICS>WATER TEMPERATURE Place: Place_Keyword_Thesaurus: Common geographic areas Place_Keyword: fUS = United States Place_Keyword: fUS24 = Maryland Place_Keyword: h02080101 = Lower Chesapeake Bay Place_Keyword: h02060001 = Upper Chesapeake Bay Place_Keyword: f24005 = Baltimore Place_Keyword: f24029 = Kent Place_Keyword: f24025 = Harford Place_Keyword: f24035 = Queen Anne's Place_Keyword: f24009 = Calvert Place_Keyword: f24003 = Anne Arundel Place_Keyword: f24015 = Cecil Place_Keyword: f24019 = Dorchester Place_Keyword: f24037 = Saint Mary's Place_Keyword: f24039 = Somerset Place_Keyword: f24041 = Talbot Temporal: Temporal_Keyword_Thesaurus: USGS Thesaurus Temporal_Keyword: summer Temporal_Keyword: spring (season) Temporal_Keyword: autumn Temporal_Keyword: winter Access_Constraints: NONE Use_Constraints: Acknowledgement of the MD Department of Natural Resources, Resource Assessment Service as a data source would be appreciated in products developed from these data. Please use the following citation: Maryland Department of Natural Resources, Resource Assessment Service. Eyes on the Bay. URL: . Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Renee Karrh Contact_Position: Program Manager Contact_Address: Address_Type: Mailing and physical Address: 580 Taylor Avenue, C2 City: Annapolis State_or_Province: Maryland Postal_Code: 21401 Country: USA Contact_Voice_Telephone: 410.260.8630 Contact_Electronic_Mail_Address: renee.karrh_nospam_@maryland.gov[Remove _nospam_ for valid email address] Browse_Graphic: Browse_Graphic_File_Name: MDDNR Mainstem Monitoring Project 2024 Station Map . If the map URL raises a file not found error, drill down from . Browse_Graphic_File_Description: Map of twenty-two 2024 Maryland Chesapeake Bay mainstem water quality monitoring sites. Browse_Graphic_File_Type: PDF Data_Set_Credit: Maryland Department of Natural Resources (MDDNR) Resource Assessment Service (RAS) staff collected the samples and processed the data. The Nutrient Analytical Services Laboratory (NASL) at the University of MD Center for Environmental Science, Chesapeake Biological Laboratory analyzed chlorophyll, nutrient, and suspended solids samples. The project was made possible with funding provided by The State of Maryland and the United States Environmental Protection Agency Chesapeake Bay Program. Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: QUALITY ASSURANCE/QUALITY CONTROL Maryland Department of Natural Resources followed specific procedures to ensure that the mainstem 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 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 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 2024: Foggy conditions were reported at LE2.3, CB1.1, CB2.1, CB2.2, CB3.2, and CB3.3C. No pycnocline was reported at stations CB4.4, CB5.1, and CB5.2 and above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of station total water column depth. Surface and above pycnocline water samples collected at station CB3.1 were taken from the same bottle. Black birds were noted as circling at station CB2.2. Bottom and below pycnocline water samples collected at station CB3.1 were taken from the same bottle. Conductivity readings from 0.5 to 2.0 m depth were unstable at station CB4.1C. Surface conductivity changed from 21200 to 20000 µS/cm at station CB4.4. February 2024: Foggy conditions were reported at LE2.3, CB5.2, and CB5.3. Surface and above pycnocline water samples collected at station CB5.2 were taken from different bottles. March 2024: No pycnocline was reported at stations CB2.2, CB4.3C, CB5.1, and CB5.2 and above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of station total water column depth. Surface and 1.0 m values were the same at station CB4.3E and 0.5 and 1.0 m values were the same at station CB5.1W. Surface conductivity changed at stations CB4.1C and CB4.2C. Water pump issues were reported at station CB2.2. April 2024: No pycnocline was reported at station CB2.2 and above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of station total water column depth. Bottom and below pycnocline water samples collected at station CB3.2 were taken from the same bottle. The thermometer used to measure air temperature was in the sun when recorded at station CB5.3. Water pump issues were reported at station CB2.1. May 2024: A pycnocline was not evident at station CB2.2. Above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of total water column depth at these stations. Water quality values were the same at depths 0.5 and 1.0 m at both stations CB5.1 and CB4.4. June 2024: The first June mainstem survey was conducted June 3-5. Scoping is a term used to describe situations when strong currents and winds make it difficult to maintain the water quality data sonde at a depth long enough for readings to stabilize. Meter scoping was noted at station CB3.3C. No pycnocline was reported at stations LE2.3 and CB2.2 and above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of station total water column depth. The thermometer used to measure air temperature was in the sun when recorded at station CB3.3C. At stations LE2.3 and CB3.3W, the 0.5 and 1.0 m values were the same. The second June mainstem survey was conducted June 25-27. Overnight thunderstorms were noted at stations sampled on 27-June. A pycnocline was not evident at stations CB3.3C, CB2.2, and CB3.1. Above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of total water column depth at these stations. Meter scoping was noted at station CB5.1. Water quality values were the same at depths 0.5 and 1.0 m at both stations CB5.1 and CB4.4. Bottom and below pycnocline water samples collected at station CB3.2 were taken from the same bottle. Issues were reported with the plug for the submersible pump used at station CB4.3E. July 2024: The first July mainstem cruise was conducted July 15-17. There was no pycnocline at stations CB2.2 and CB3.2, and above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of stations total water column depths. Hazy conditions were reported at stations CB5.2, CB3.3C, CB3.3E, CB3.3W, CB4.1C, CB4.1W, CB4.2C, CB4.2E, CB4.2W, CB4.3W, and CB1.1. Meter scoping was noted at stations CB5.3, CB4.1C, and CB4.1W. Dissolved oxygen could not be post calibrated at station CB5.1W, but data appear normal. At stations CB5.3 and CB4.1W, the 0.5 and 1.0 m values were the same. Water column measurements only (no pigment or nutrient samples) were collected during the second July (30-31) mainstem survey. August 2024: The first August mainstem cruise was conducted August 12-14. Hazy conditions were noted at stations sampled on 14-August. There was no pycnocline at stations LE2.3, CB4.1E and CB2.2, so above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of stations total water column depth. Bottom and below pycnocline samples were collected from a single bottle at stations CB4.2C. Surface conductivity changed by 800 µS/cm at station CB3.2. The second August mainstem survey was conducted August 27-28. Overnight thunderstorms were noted at stations sampled on 27-August. Hazy conditions were also noted at stations sampled on 27-August. A pycnocline was not evident at station CB2.2. Above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of total water column depth at these stations. The 16 m and 17 m dissolved oxygen readings at station CB4.3C were double checked. September 2024: A pycnocline was not evident at station CB3.3C. Above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of total water column depth at these stations. October 2024: No pycnocline was observed at stations LE2.3, CB4.4, CB5.1, CB5.2, CB5.3, CB3.3C, CB4.1C, CB4.1E, CB4.2C, CB4.3C, and CB4.3E, so above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of stations total water column depth. Conductivity was double checked at 1.0 m and 2.0 m at station CB3.1. November 2024: Overnight rain was noted at stations sampled on 15-August. Meter scoping was noted at stations CB4.3C, CB4.4, and CB5.1. No pycnocline was observed at stations LE2.3, CB3.2, CB3.3C, CB4.1C, CB4.2C CB4.3C CB4.4, CB5.1, and CB5.2, so above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of stations total water column depth. Values were the same at both 0.5 and 1.0m depths at stations CB4.3C, CB4.2C, CB5.1 and CB5.2. Bottom and below pycnocline samples were collected from a single bottle at station CB3.1. December 2024: Meter scoping was noted at stations LE2.3 and CB4.1C. No pycnocline was observed at stations LE2.3, CB4.1C, CB4.2C, CB4.3C, CB4.4, CB5.1, and CB5.2, so above pycnocline and below pycnocline water samples were collected at 1/3 and 2/3 of stations total water column depth. Values were the same at both 0.5 and 1.0m depths at stations LE2.3 and CB5.2. Logical_Consistency_Report: For logistical reasons, station LE2.3, a Potomac River water quality sampling project station, is routinely sampled during Chesapeake Bay mainstem sampling cruises. Tributaries monitoring project boat stations are sampled using small boats for most of the year, however the larger mainstem sampling vessel is used when weather and safety are concerns. In addition to mainstem stations sampling, one or more of the following tributaries project stations may be sampled using the larger vessel during December, January and February surveys: EE1.1, EE2.2, EE2.1, ET4.2 and WT5.1. For logistical reasons, water samples for mainstem project station CB5.1W are routinely collected on the Tributaries project Patuxent boat survey. Two mainstem surveys were scheduled and conducted in each of the months: June, July and August 2024. Water column measurements only (no pigment or nutrient samples) were collected during the second July mainstem survey. ADDITIONAL COMMENTS January 2024: The above pycnocline (AP) composite plankton sample for station CB3.1 should have been collected at 8.0 m depth. Sampling was originally scheduled for January 16-18 and was rescheduled to January 23-25 due to extreme cold and high winds. February 2024: The R/V Rachel Carson had major engine failure of the port and starboard engines on 12-February. Stations CB3.3C, CB3.1, and CB3.2 were sampled on 26-February on a small boat, MD2134A. Stations CB2.2, CB2.1, and CB1.1 were sampled on 26-February on a small boat, MD2538A. March 2024: The R/V Bay Eagle was used during sampling. Sampling was delayed a week due to the availability of the R/V Bay Eagle. Due to high wind predictions, stations were sampled out of order, and CB3.3E was sampled on 19-March instead of on 18-March. The AP composite plankton sample for station CB4.2C should have been collected at 8.0 m depth. April 2024: The R/V Bay Eagle was used during sampling. The AP composite plankton sample for station CB4.4 should have been collected at 8.0 m depth. May 2024: The R/V Bay Eagle was used during sampling. The below pycnocline water sample should have been collected at 6.0 m depth. June 2024: The R/V Bay Eagle was used during the first cruise sampling. Vessel 5502 was utilized during the second June cruise. During the second June cruise, sampling was canceled on 24-June due to hydraulic issues. July 2024: The R/V Bay Eagle was used during the first cruise sampling. Vessel 5502 was utilized during the second July cruise. The second July cruise was blown out on 29-July. The cruise started with upper Bay first due to unfavorable weather conditions in the mid and lower Bay. On 30-July sampling started with station CB5.3W and ended with CB1.1, and on 31-July sampling started with stations CB4.1W and ended with CB5.1. The AP composite plankton sample for station CB4.1E should have been collected at 10.0 m depth. At the same station, CB4.1E, the boat lost depth and had to be repositioned. Station LE2.3 was not sampled due to engine issues. August 2024: The R/V Bay Eagle was used during both sampling cruises. The AP composite plankton sample for station CB5.2 should have been collected at 12.0 m depth on 12-August. September 2024: The R/V Bay Eagle was utilized for the majority of the cruise. MD2130A was used to sample stations CB3.3W and CB3.2 and MD2134A was used to sample stations CB3.1, CB2.2, CB2.1, and CB1.1. Due to the weather and boat scheduling issues, stations CB5.1, CB4.4, CB4.3E, CB4.3C, CB4.3W, CB4.2W, CB4.2C, CB4.2E, CB4.1E, CB4.1C, and CB4.1W were sampled on 23-September, and stations CB5.2, CB5.3, and LE2.3 were sampled on 24-September. October 2024: The R/V Bay Eagle was used during sampling. November 2024: The R/V Bay Eagle was used during sampling. December 2024: The R/V Bay Eagle was used during sampling. Completeness_Report: Two mainstem surveys were conducted in each of months: June, July, and August 2024. Water column measurements only (no pigment or nutrient samples) were collected during the second July mainstem survey. ADDITIONAL COMMENTS January 2024: LI-COR readings were not collected at stations CB5.3W, CB4.4, and CB1.1. February 2024: The R/V Rachel Carson had major engine failure of the port and starboard engines on 12-February. Sampling resumed on 26-February using small boats. Stations CB4.1C, CB4.2C, CB4.3C, CB4.4, and CB5.1 were not sampled due to catastrophic engine failure. March 2024: Conditions were too rough at station CB5.1W to collect LI-COR readings. April 2024: The conductance failed post calibration checks at all stations, except stations CB1.1, CB2.1, CB2.2, and CB3.2. June 2024: Wave height was not recorded during the first June cruise at station CB3.1. July 2024: During the July 15-17 cruise, LI-COR readings were not collected at stations CB5.3, CB4.1W, and CB3.3W. Stations LE2.3, CB5.2, and CB5.3 were not sampled on 31-July due to engine troubles. During the July 30-31 cruise, LI-COR readings were not collected at stations CB5.1, CB4.4, CB3.3E, CB3.3C, CB3.3W, CB3.2, CB3.1, CB2.2, CB2.1, and CB1.1 due to rough conditions. August 2024: During the August 12-14 cruise, LI-COR readings were not collected at stations CB4.3C, CB4.3W, CB4.2C, CB4.2E, CB4.1E, CB4.1C, CB4.1W, CB3.3E, CB3.3C, CB3.3W, CB3.2, CB3.1, CB2.2, CB2.1, and CB1.1. During the August 27-28 cruise, LI-COR readings were not collected at stations LE2.3, CB5.3, CB5.2, CB5.1, and CB4.4. September 2024: Station CB5.1W was not sampled due to rough conditions. No LI-COR readings were taken at CB3.3W. October 2024: No LI-COR readings were taken at CB5.1W due to equipment failure. November 2024: Station CB5.3 was not sampled due to rough conditions. Due to a broken instrument, no LI-COR readings were taken at CB5.1W. LI-COR readings were not collected at stations LE2.3, CB5.2, CB5.1, CB4.3C, CB4.2C, CB4.1C, and CB3.3C due to rough conditions. December 2024: Station CB5.3 was not sampled due to rough conditions. LI-COR readings were not collected at stations LE2.3, CB5.2, CB5.1, CB4.4, CB4.3C, CB4.2C, CB4.1C, and CB3.3C due to rough conditions. There were no known completeness issues for the months: May 2024. Lineage: Process_Step: Process_Description: SONDE CALIBRATION and POST-CALIBRATION The Yellow Springs Instrument (YSI) EXO2 data sondes were maintained and calibrated before and after each cruise in accordance with manufacturer's recommendations. WATER COLUMN PROFILE SAMPLING PROTOCOLS: A profile of temperature, specific conductance, dissolved oxygen, and pH was obtained from the water column by deploying the data sonde at 0.5 m, 1.0 m, 2.0 m and 3.0 m depth intervals below the surface. Thereafter readings were taken at 2.0m intervals and at the bottom. 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 10.0m, readings were taken at 1.0 m intervals. GRAB SAMPLING DEPTH PROTOCOLS: At stations where two depths were sampled, collections were taken at 0.5 m below the surface, and 1.0 m above the bottom. If the station total depth was equal to 1.5 m, the bottom sample was also collected at 0.5 m. Great caution was exercised when taking bottom samples; if the bottom was disturbed and bottom sediments appeared to have been included, the sample was dumped out and collected after the sediments had settled. Alternately, the sample was collected slightly higher in the water column and the new bottom sample depth was noted. At stations where 4 depths were sampled and a pycnocline existed, collections were taken at 0.5 m below the surface, 1.5 m above the upper boundary of the pycnocline, 1.5 m below the lower boundary of the pycnocline, and 1.0 m above 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 the closest profile depth one third of the distance from the surface to the bottom, at the closest profile depth two thirds of 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. Process_Date: Unknown Process_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Kristen Heyer Contact_Position: Manager, Water Quality Monitoring Contact_Address: Address_Type: Mailing and physical Address: 1919 Lincoln Drive City: Annapolis State_or_Province: Maryland Postal_Code: 21401 Country: USA Contact_Voice_Telephone: 410.990.4600 Contact_Electronic_Mail_Address: kristen.heyer_nospam_@maryland.gov[Remove _nospam_ for valid email address] Process_Step: Process_Description: LABORATORY ANALYSIS - CBL The University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory, 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. 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". Process_Date: Unknown Process_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Jerry Frank Contact_Position: Manager, Nutrient Analytical Services Laboratory Contact_Address: Address_Type: Mailing and physical Address: University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory, 146 Williams Street, P.O. Box 38 City: Solomons State_or_Province: Maryland Postal_Code: 20688 Country: USA Contact_Voice_Telephone: 410.326.7252 Contact_Electronic_Mail_Address: frank_nospam_@umces.edu[Remove _nospam_ for valid email address] Process_Step: Process_Description: VERIFICATION AND DATA MANAGEMENT: 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. Process_Date: Unknown Process_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Renee Karrh Contact_Position: Program Manager Contact_Address: Address_Type: Mailing and physical Address: 580 Taylor Ave., C2 City: Annapolis State_or_Province: MD Postal_Code: 21401 Contact_Voice_Telephone: 410.260.8630 Contact_Electronic_Mail_Address: renee.karrh_nospam_@maryland.gov[Remove _nospam_ for valid email address] Spatial_Data_Organization_Information: Indirect_Spatial_Reference: Chesapeake Bay, Maryland Direct_Spatial_Reference_Method: Point Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Geographic: Latitude_Resolution: 0.0001 Longitude_Resolution: 0.0001 Geographic_Coordinate_Units: Decimal degrees Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1983 Ellipsoid_Name: Geodetic Reference System 80 Semi-major_Axis: 6378137 Denominator_of_Flattening_Ratio: 298.257 Entity_and_Attribute_Information: Overview_Description: Entity_and_Attribute_Overview: This metadata record is a description of the Maryland Department of Natural Resources Chesapeake Bay Water Quality Monitoring Program - Chemical and Physical Properties Component Database for the Maryland Chesapeake Bay Mainstem. Project data are an aggregation of data collected at twenty-two Maryland mainstem stations during 2024. The data are contained in five related entities (tables): Light_Attenuation_Data, Monitoring_Event_Data, Optical_Density_Data, Station_Information, and Water_Quality_Data. Each table contains attributes (fields). The entity Light_Attenuation_Data is comprised of the attributes: Agency, BiasPC, CBSeg2003, CBSegmentShed2009, Cruise, Depth, Details, EventId, FIPS, HUC8, HUC12, Lab, Latitude, Layer, Longitude, LowerPycnocline, MeasureValue, Method, MonitoringStation, Parameter, PrecisionPC, Problem, Program, Project, Qualifier, SampleDate, SampleReplicateType, SampleTime, SampleType, Source, Station, TierLevel, TotalDepth, Unit and UpperPycnocline. The entity Monitoring_Event_Data is comprised of the attributes: Agency, AirTemp, CBSeg2003, CBSegmentShed2009, CloudCover, Cruise, Details, EventId, FieldActivityEventType, FieldActivityRemark, FieldActivitySiteTypeCodeDescription, FIPS, FlowStage, GaugeHeight, HUC8, HUC12, Latitude, Longitude, LowerPycnocline, MonitoringStation, PrecipType, Pressure, Program, Project, SampleDate, SampleTime, Source, Station, TideStage, TierLevel, TotalDepth, UpperPycnocline, WaveHeight, WindDirection and WindSpeed. The entity Optical_Density is comprised of the attributes: Agency, BiasPC, CBSeg2003, CBSegmentShed2009, Cruise, Depth, Details, EventId, FIPS, HUC8, HUC12, Lab, Latitude, Layer, Longitude, LowerPycnocline, MeasureValue, Method, MonitoringStation, Parameter, PrecisionPC, Problem, Program, Project, Qualifier, SampleDate, SampleReplicateType, SampleTime, SampleType, Source, Station, TierLevel, TotalDepth, Unit and UpperPycnocline. The entity Station_Information is comprised of the attributes: CBSeg2003, CBSeg2003Description, CBSegmentShed2009, CBSegmentShed2009Description, CountyCity, FallLine, FIPS, HUC12, HUC8, Latitude, LLDatum, Longitude, State, Station, StationDescription, USGSGage, UTMX and UTMY. The entity Water_Quality_Data is comprised of the attributes: Agency, BiasPC, CBSeg2003, CBSegmentShed2009, Cruise, Depth, Details, EventId, FIPS, HUC8, HUC12, Lab, Latitude, Layer, Longitude, LowerPycnocline, MeasureValue, Method, MonitoringStation, Parameter, PrecisionPC, Problem, Program, Project, Qualifier, SampleDate, SampleReplicateType, SampleTime, SampleType, Source, Station, TierLevel, TotalDepth, Unit and UpperPycnocline. Entity_and_Attribute_Detail_Citation: Water Quality Database - Database Design and Data Dictionary, Prepared For: U.S. Environmental Protection Agency, Region III, Chesapeake Bay Program Office, January 2004. . An updated version of the data dictionary is a Chesapeake Bay Program work in progress. 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, 2022 - June 30, 2023. . Methods and Quality Assurance for Chesapeake Bay Water Quality Monitoring Programs. Chesapeake Bay Program, May 2017, CBP/TRS-319-17 . Distribution_Information: Distributor: Contact_Information: Contact_Person_Primary: Contact_Person: Mike Mallonee Contact_Position: Water Quality Data Manager Contact_Address: Address_Type: Mailing and physical Address: 1750 Forest Drive, Suite 130 City: Annapolis State_or_Province: Maryland Postal_Code: 21401 Country: USA Contact_Voice_Telephone: 410.267.5785 Contact_Electronic_Mail_Address: mmallone_no_spam_@chesapeakebay.net[Remove _nospam_ for valid email address] Resource_Description: Downloadable data Distribution_Liability: None of the Chesapeake Bay Program partners nor any of their employees, contractors, or subcontractors make any warranty, expressed or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information or data contained within the web site. Reference to any specific commercial products, processes, or services or the use of any trade, firm, or corporation name is for the information and convenience of the public and does not constitute endorsement, recommendation or favoring by the Chesapeake Bay Program partners. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: ASCII file, formatted for text attributes, declared format Format_Information_Content: Light_Attenuation_Data, Monitoring_Event_Data, Optical_Density, Station_Information, and Water_Quality_Data. File_Decompression_Technique: No compression applied Transfer_Size: 10.2 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: Access_Instructions: Data are available through the Chesapeake Bay Program's Data Hub. Select Water Quality Database (1984-Present). Access the data by following web site (see network resource name) instructions. Fees: None Metadata_Reference_Information: Metadata_Date: 20250627 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Mark Trice Contact_Organization: Maryland Department of Natural Resources, Resource Assessment Service Contact_Position: Chief, Water Quality Informatics Contact_Address: Address_Type: Mailing and physical Address: 580 Taylor Avenue, D2 City: Annapolis State_or_Province: Maryland Postal_Code: 21401 Country: USA Contact_Voice_Telephone: 410.260.8630 Contact_Electronic_Mail_Address: mark.trice_nospam_@maryland.gov[Remove _nospam_ for valid email address] Metadata_Standard_Name: Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998