- Chesapeake Bay Program Water Quality Database (Includes VECOS verification data)

- CBNERRS Resources and Publications

- Submerged Aquatic Vegetation in Chesapeake Bay and Coastal Bays

- Maryland Eyes on the Bay: Maryland Tidal Water Quality Information

Dataflow Monitoring

Dataflow is a compact, self-contained surface water quality mapping system, suitable for use in a small boat operating at speeds of about 25 KT. The system collects water through a pipe ("ram") deployed on the transom of the vessel, pumps it through an array of water quality sensors, and then discharges the water overboard. The system collects samples approximately once every 3-4 seconds. The DATAFLOW system utilizes a YSI 6600 multiparameter, sonde equipped with a flow-through chamber which gives readings on water temperature, salinity, pH, chlorophyll, turbidity, and dissolved oxygen. The sonde transmits data collected from the sensors directly to a 600 MHz embedded computer board contained in a waterproof Pelican case using a data acquisition system created with LabView software (National Instruments, Inc.). Custom software written in the Lab View environment provides for data acquisition, display, control, and storage. Real-time graphs and indicators provide feedback to the operator in the field, ensuring quality data is being collected. The system is also equipped with a Garmin GPSMAP 168 Sounder. This unit serves several functions including chart plotting, position information, and depth. The unit is WAAS (Wide Area Augmentation System) enabled providing a position accuracy of better than three meters 95 percent of the time. DATAFLOW cruises take place once a month in each of the Chesapeake Bay Program Segment of interest. Two types of cruise tracks are utilized depending on the river morphology of the segment being monitored. Due to the width of larger segments such as the York River Polyhaline (YRKPH), a series of tracks running parallel to the shoreline along fixed depth contours is followed. The track follows the shoreline along the <2 meter depth contour upriver, then turns down river following a mid depth contour (approximately 5 meters), it then goes upriver along the channel (>10 meters depth), then finishes with a down river leg along the other shoreline in the shallows. In narrower segments such as those in the Mattaponi and Pamunkey Rivers a single cruise track is used, traveling upriver to parallel the tidal advancement. Verification stations, five in each segment, are sampled for a number of parameters including total suspended solids, extracted chlorophyll, light attenuation, organic and inorganic nutrients, and dissolved oxygen via Winkler titration to verify that the YSI 6600 is functioning properly.

Continuous Monitoring

The continuous monitoring stations are used to monitor water quality parameters including depth, water temperature, salinity, pH, chlorophyll, turbidity, and dissolved oxygen using YSI 6600 data sondes with the Clean Sweep Extended Deployment System, which wipes the sensors at 15-minute intervals. These stations provide long term measurements that can be supplemented with shorter term monitoring, such as the DATAFLOW cruises, and other process-oriented studies. The fixed stations are designed to be free standing, away from piers and dock areas where boat traffic may lead to episodes of increased turbidity. The stations are placed at a depth of approximately 1.5 meters MLW. At each fixed station a piling is driven into the sediment and is surrounded by a protective frame. A perforated PVC pipe is mounted to the piling. Within the PVC housing, an YSI 6600 data logging sonde is secured 0.5 meters above the bottom. Sondes are deployed for a maximum of 7 - 10 days. Deployment duration is dependent upon the fouling regime of the area in which the sonde is located. Upon return to the laboratory the sondes are post calibrated, cleaned, and routine maintenance is performed as needed. The sondes are then stored until they are calibrated just prior to their next deployment. All calibrations and maintenance are completed in accordance with the YSI, Inc. operating manual methods (YSI 6-series Environmental Monitoring Systems Manual; YSI, Inc. Yellow Springs, OH).

Profiler Monitoring

YSI Profiler systems, consisting of an integrated system of hardware and software, are currently being deployed from June through September in the deeper regions of the Rappahannock and York Rivers where severe hypoxia occurs in the warmer months. The vertical profiler is a fixed mounted system consisting of a multi-parameter YSI 6600 V2 data sonde, a computer controller (YSI 6960), and a motor-driven winch assembly (YSI 6955) that automatically collects hourly readings of temperature, salinity, conductivity, dissolved oxygen, pH, turbidity and chlorophyll from multiple depths along the depth profile. It uses a depth sounder to automatically compensate for varying tidal water levels. The controller is remotely accessed and programmed via telemetry and data is delivered hourly to a VIMS computer. A pier-based vertical profiler is positioned on a deep water US Coast Guard pier in the lower York River segment (YRKPH). A pontoon-based system is located in the Rappahannock River segment (RPPMH). Deployment duration is dependent upon the fouling regime of the area. At the end of each deployment the in situ multi-parameter data sonde is replaced with a newly calibrated unit. Upon return to the laboratory the previously deployed sonde is post calibrated, cleaned and routine maintenance is performed as needed. Each sonde is then stored until it is calibrated just prior to the next deployment. All calibrations and maintenance are completed in accordance with the YSI, Inc. operating manual methods (YSI 6-series Environmental Monitoring Systems Manual; YSI, Inc. Yellow spring, OH). The profiler data is updated annually on the VECOS website to include all data from the previous year.

Longterm Monitoring

As part of the Chesapeake Bay Monitoring Program, stations have been sampled routinely in the Virginia Mainstem Chesapeake Bay and the tidal portions of the major Virginia tributaries since 1985. Sampling frequency has varied from a maximum of 20 times per year in the early days of the monitoring program to 12 times per year more recently. Tributary stations are sampled by the Virginia Department of Environmental Quality. Mainstem Chesapeake stations were sampled by the Virginia Institute of Marine Science until 1996 when the monitoring program was taken over by Old Dominion University. Over the span of the monitoring program, 35 stations have been sampled consistently in the tributaries and 28 in the mainstem. In the mainstem monitoring program, a Yellow Springs Instruments (YSI) multi-parameter 6600V2 sampling probe is used to measure dissolved oxygen, pH, temperature, salinity and conductivity at 1 meter depth intervals at each station. At tributary stations, these parameters are measured using either a Hydrolab Datasonde 5 multi-probe, a YSI 600 XL multi-probe or a YSI 6920V2 multi-probe depending on location. Secchi depths are determined using a 20 inch diameter Secchi disc at all stations.

Current year data are obtained after each monitoring cruise from VADEQ and ODU. These data are then uploaded into the VECOS database and are considered provisional. As soon as the most recent complete year of Virginia tributary and mainstem monitoring data are available on the Chesapeake Information Management System (CIMS), it is uploaded to the VECOS database to replace the corresponding provisional data.

Data Disclaimer

The data on this website should be considered provisional. It has passed rigorous quality assurance and quality control checks, but may be subject to change upon final review at the end of the calendar year. While we make every effort to provide correct and complete data in the graphs and image summaries, VIMS provides no warranty, expressed or implied, as to the accuracy, reliability or completeness of the furnished data. Data users are cautioned to consider carefully the provisional nature of the information before using it for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences. Information presented on this website is considered public information (unless otherwise noted) and may be distributed or copied. Use of appropriate byline/photo/image credit is requested. Some of the documents on this server may contain live references to information created and maintained by other organizations. Please note that VIMS does not control and cannot guarantee the relevance, timeliness, or accuracy of these outside materials.

Error Codes for Shallow Water Monitoring Data

Users of the VECOS website can currently access five types of water quality data: Dataflow data, fixed continuous station data, real-time continous station data, longterm data, and profiler data. Descriptions of these type of data can be found in the About The Data section of this website.

All monitoring is organized by Chesapeake Bay Program segments, which are derived from the salinity regime of the area. For instance, the main stem of the York River is represented by two segments: the York Polyhaline (YRKPH) and York Mesohaline (YRKMH).

To navigate through this site, use the map or dropdown boxes on the homepage to access sites of interest. A dynamic legend is included in the map on the homepage that allows the user to hide or show data types of interest on the map. Also note that the categories of data (water quality, weather, or segments) can be collapsed or expanded within the legend. Hovering over the icons on the map results in the target station or Dataflow cruise name floating by the cursor. Click on a segment or station of interest to visit the associated data page. On this page the user can navigate to another segment by using the Regional View Map on the right or by navigating back to the homepage by click on the "home" link on the left. A description and image of the cruise segment or continuos station is found on the right side of the data page.

Dataflow Data

The Dataflow data detail page may be accessed from the homepage by clicking on a purple circle icon on the map or selecting a Dataflow cruise segment from the dropdown menu. The associated detail page dispays interpolations for the most recent cruise date for each parameter. The user can switch to a different date by using the scroll window and clicking on the cruise date of interest. The selected data may also be downloaded by clicking on the "Download Data for Selected Date" button

Fixed Continuous Station Data

The Continuous data detail page may be accessed from the homepage by clicking on a green (only continuous) or blue (continuous and realtime access) triangle icon on the map or selecting a continuos station of interest from the dropdown menu. As a default, the associated continuous detail page will plot the most recent 7 days of archived data. To view data for another set of dates, the user can use the calendars to select a start and end date and then click the “View Data Plots” button. At any time the selected range of data may be downloaded by clicking the “Download Archived Data” button.

Realtime Continuous Station Data

When the user selects a station with Realtime data (blue triangle icon on map), the browser is directed to the associated continous station detail Page. Realtime station detail pages have the same options as on the above description of the Fixed Continuous Station Data, but also includes a “View Realtime Data” button. If you click this button a new browser window will direct the user to a page hosted on a partner's website displaying the realtime water quality or weather data for this site. The realtime data is not available for download.

Longterm Station Data

The Longterm data detail page may be accessed from the homepage by clicking on a blue square icon on the map or selecting a Longterm station from the dropdown menu. The graphs allow the user to interactively view surface and bottom values of Dissolved Oxygen (mg/l), Water Temperature (C), Salinity (ppt), and Secchi Depth (m) for the current station. Data are from the Chesapeake Bay Program fixed station water quality monitoring program. Along with the value measured on each date, the graphs show the longterm minimum and maximum values. Rolling the mouse over the data lines on the graph will allow you to view the data values for a particular date at the top of the graph. Just below the top graph is a date range selector for all graphs on the page. The highlighted area within the selector determines the range of dates shown in all the graphs on the page. You can adjust this range by using your mouse to expand and contract the highlighted range in the selector. Once the user sets the range, the slider at the bottom of the range is used to scroll through the entire data history. The user can change the parameter being graphed by selecting a new parameter from the menu at the upper left hand corner of each graph. Clicking the “Download Archived Data” button will download all of the data for the current station.

Profiler Data

Downloaded Data

Once you have downloaded data files you will see that for some data, the cell is blank and there is an error code associated with the data. For definitions of the error codes see the "About the Data" link on the menu located on the top menu of this website.

The Virginia Estuarine and Coastal Observing System (VECOS) is a website designed to distribute water quality data sampled from the Chesapeake Bay and associated tributaries within Virginia.

These data are provided from a variety of data collection programs, including high resolution mapping of surface water quality (Dataflow), continuous measurements of water quality taken from fixed, shallow water monitoring stations (Continuous), continuous measurements taken from deeper waters along multiple depths (Profiler), and long-term routine sampling, typically taken 12-20 times per year since 1985 (Longterm). Further Information about these data types can be found in the About The Data section of this website.

VECOS eases access to these data for a variety of users by providing quick navigation to data of interest, fast and simple access to downloadable datasets, and interactive online visualizations of the data. Information about how to use VECOS can be found in the Using The Site section of this website.