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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_STAIDStation 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 upstream 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_FIELDField 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.
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_HYDROResults 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
DEP GIS Group and DWM are maintaining this data layer.
Last Updated 5/30/2007
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