OVERVIEW

The DEP Division of Watershed Management (DWM) Monitoring Stations datalayer represents points on rivers, ponds and lakes where water-quality samples were taken by DWM staff during 1995 and 1996. The datalayer was compiled by DWM and the MA Department of Environmental Protection GIS Group. Most station locations were chosen to support the environmental monitoring phase of the Massachusetts Watershed Initiative. New stations will be added as additional watersheds complete this phase and the related monitoring data pass the DWM quality-control and quality-assurance checks. Monitoring results are stored in related INFO tables described under ATTRIBUTES (below). Data maintained in these tables is reported by the DWM in assessment reports. These are available upon request by contacting the Division of Watershed Management at 508-792-7470. In ArcSDE the layer is named DWMSTATIONS_PT.

The data layer was created using field descriptions recorded by the staff at the time the samples were taken. These transcriptions were then transferred to 1:24000 or 1:25000 USGS topographic quadrangles. Station identification codes are assigned by DWM and used in the Water Quality Data Database. Tables from the Water Quality Database can be linked with this data layer using the UNIQUE_ID item. Stations in approximately 12 major basins are included in this data layer.

Locations recorded on 1:24000 and 1:25000 USGS topographic maps were transferred to a point coverage using on-screen digitizing and registered images of the USGS topographic maps. Watershed teams were consulted to ensure the accuracy of this transferal.

This data layer has a point attribute table with the following items:

  UNIQUE_ID    code corresponding to DWM database
  LONG         longitude
  LAT          latitude

Data generated from surveys conducted by DWM staff are maintained in the four tables listed below.

DWMSTATIONS_PT_STAID
Station location and identification information. This table contains fields that describe the station. This table is related to the data coverage by use of the UNIQUE_ID field. The UNIQUE_ID is also used to relate to the FIELD table. This table contains 1 record for each station location. Fields in the STAID Table: 

  UNIQUE_ID   Unique identifier assigned individual monitoring stations used to
             relate to point coverage and FIELD table
  STATUS      Status of data at time of publication
  TYPE        Station type (W=Water Column, D=Discharge Pipe - Not an instream station)
  SARIS       Stream and River Identification System code
  PALIS       Pond and Lake Identification System Code
  WBNAME      Name of water body where the station is located
  MILEPT      River Mile up-stream from mouth of river (Mouth is defined as river
             mile 0.0). Code "-9" are stations at the confluence of rivers.
  STAID       Station ID assigned and used by Watershed Team
  DESCRIPTOR  Detailed description of station location

DWMSTATIONS_PT_FIELD
Field record of sampling surveys. This table records the date and time that samples were taken in the field as well as information for tracking the sample and quality control and assurance. This table is related to the STAID table by the UNIQUE_ID field (which in turn is linked to the data layer). It is possible to relate the FIELD table directly to the data layer using the UNIQUE_ID field; however, it is not recommended. This table contains one record for each visit to a station during a sampling survey. Most stations are visited more than once. Fields in the Field table: 

  UNIQUE_ID  Unique identifier assigned individual monitoring stations used
            to relate to FIELD table
  OWMID      Identifying code assigned to individual samples. Used to link
            to both the LAB and HYDRO tables.
  STATUS     Status of data at time of publication
  QAQC       Identifies field QAQC samples (BLANK = Distilled Water Blank,
            Split samples are indicated by populating this field with the
            OWMID of the paired sample)
  SDEPTH     Depth at which discrete samples are collected for laboratory
            analysis ONLY. This field is only populated where sampling
            apparatus allowing collection of samples below the surface has been used.
  DATE       Date of sample collection
  TIME       Time of sample collection in 24-hour format
  WDO        Azide modification of Winkler method on grab sample
  DTEMP      Temperature, in degrees Celsius, in field using a hand-held thermometer
  METER      Meter used for in situ determinations of one or more of the following:
              depth, temperature, salinity, dissolved oxygen, specific
            conductivity, and pH. (YSI=Yellow Springs Instruments, HLB=Hydrolab
            Surveyor II without data logging). Note: Measurements using a Hydrolab
            Surveyor 3 multiprobe instrument with data logger are maintained in
            the HYDRO table.
  MDEPTH     Depth in meters (m) measured by instrument Indicated in the field METER
  MTEMP      Temperature in degrees Celsius (°C) measured by instrument Indicated
            in the field METER
  MSALINITY  Salinity in parts per thousand (ppt) measured by instrument Indicated
            in the field METER
  MDO        Dissolved Oxygen in milligrams per liter (mg/l measured by instrument
            Indicated in the field METER
  MSPECOND   Specific Conductivity (?mhos/cm) measured by instrument Indicated in
            the field METER
  MPH        pH in standard pH units (SU) measured by instrument Indicated in the
            field METER.

DWMSTATIONS_PT_LAB
Results of laboratory analysis of discrete samples collected by DWM staff during a sampling survey and analyzed at the Wall Experiment Station. The LAB table is related to the FIELD table using the OWMID field. This table contains one record for each set of sampling bottles collected at a station and sent to the lab for analysis. 

Codes used in populating data into the fields below are: 
Results reported less than detection limit are entered as negative values. (i.e. a result of <0.02 is entered as -0.02) 
-7 = Interference 
-8 = Missing data (i.e. broken bottle, lost sample, censored data) 
-9 = Result was reported as a literal zero "0". Null value indicates no data. 

  OWMID        Identifying code assigned to individual samples. Used to relate
              to the FIELD table.
  STATUS       Status of data at time of publication
  PH          pH (standard pH units).
  ALK         Alkalinity (mg/l)
  HARD        Hardness (mg/l)
  SPECCOND     Specific Conductivity (?mhos).
  CHLORIDE     Chlorides (mg/l).
  SSOLIDS      Suspended solids (mg/l).
  TSOLIDS      Total solids (mg/l).
  TURB        Turbidity (NTU).
  TKN         Total Kjeldahl Nitrogen (mg/l).
  AMMONIA      Ammonia Nitrogen (mg/l).
  NITRATE      Nitrate Nitrogen (mg/l)
  TPHOS        Total Phosphorus (mg/l).
  EXTBLAB      Yes/No. Indicates if bacteria results are from a lab other than
              the Wall Experiment Station.
  TCOLIFORM    Total coliform bacteria (cfu/100 ml).
  FECAL        Fecal coliform bacteria (cfu/100 ml).
  FECALSTREP   Fecal Streptococci (cfu/100ml).

DWMSTATIONS_PT_HYDRO
Results of measurements made in situ using a Hydrolab Surveyor 3 multiprobe instrument with data logger. The HYDRO table is linked to the FIELD table using the OWMID field. This table contains one record for each visit to a station during a survey.

  OWMID    Identifying code assigned to individual samples. Used to link to the
          FIELD table.
  STATUS   Status of data at time of publication
  TIME     Time of measurement (Hours:minutes:seconds)
  TEMP     Temperature in degrees Celsius (°C)
  PH       pH in standard pH units (SU)
  SPCOND   Specific conductivity in microsiemens (?S/cm)
  DOSAT    Percent dissolved oxygen saturation (%)
  DO       Dissolved oxygen (mg/l)
  DEPTH    Depth in meters (m)
  TURB     Turbidity (NTU)
  DATE     Date of measurement

MAINTENANCE

DEP GIS Group and DWM are maintaining this data layer.

Last Updated 5/30/2007
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