Plum Island Ecosystems LTER Database

Acceptance and utilization of LTER data requires that:

(1) The Principal Investigator be sent a notice stating reasons for acquiring any data and a description of the publication intentions.
(2) The Principal Investigator of the data set be sent a copy of the report or manuscript prior to submission and be adequately cited in any resultant publications.
(3) A copy of any resultant publications should be sent to:

Principal Investigator
Ecosystems Center
Marine Biological Laboratory
7 MBL St.
Woods Hole, MA 02543

Dataset URLs:METADATA: HTML, Rich Text, XML(EML compliant)
DATA: Comma Delimited, Excel file with Metadata and data
Dataset ID:WAT-YSI-Urban-2001.04
Dataset Title:Year 2001, 15 minute measurements of stage, water temperature, conductivity, dissolved oxygen, and pH in a small headwater stream draining a highly suburban catchment (72% residential), Saw Mill Brook, Burlington, MA.
Investigator 1: 
First Name:Wilfred
Last Name:Wollheim
Address line 1:Morse Hall
Address line 2:UNH
Address line 3:
Zip Code:03824
Associate Investigators: Brian Pellerin
Keywords:PIE LTER, disturbance, Saw Mill Brook, suburban, discharge, water temperature, water stage, conductivity, pH, dissolved oxygen.
Abstract:Year 2001 continuous measurements, every 15 minutes, were made of stage, water temperature, conductivity, dissolved oxygen, and pH in a small headwater stream, Saw Mill Brook, Burlington, draining a highly suburban catchment (72% residential). Measurements are for part of the ice free season (June December). Discharge is determined from stage using discharge vs stage regressions. Several day gaps occur periodically due to removal for recalibration.
Contact: Plum Island Ecosystems LTER Information Manager
The Ecosystems Center
Marine Biological Lab
7 MBL St
Woods Hole, MA 02543
Phone (508) 289 7485
Online URL:
Data File URL
Data File Name WAT-YSI-Urban-2001
Beginning Date 6/22/2001
End Date 12/16/2001
Number of Data Records 15652
Other Files to Reference All in the YSI series.
Availability Status Type 1
Quality Control Information
Maintenance Description Periodic with improvement of rating curve, particularly as more high discharge events are incorporated.
Log of Changes: This file was updated in September 2007 to incorporate an improved rating curve that includes higher discharge events. Flow data from previous version is maintained for comparison.
Version 01, 30 Oct 2007 updated metadata to EML level 3+
Version 02, 21Jan2010 keyword update
Version 03, 25May2010, date and rating curve data update, revised in 2009 to standardize YSI depths to HOBO datalogger depths used in later years - uses revised rating curve that includes all measurements between 2001 and 2009
Version 04: February 17, 2014, data and metadata updated to comply with importation to Drupal and LTER PASTA. Used MarcrosExportEML_HTML (working)pie_excel2007_Sep2013.xlsm 9/30/13 02:57 PM for QA/QC to EML 2.1.0
Geographic Description Watershed water collection and stream characterization site for Saw Mill Brook (urban landuse), Burlington, MA  
Location Bounding Box    
West Bounding Coordinate    
East Bounding Coordinate    
North Bounding Coordinate    
South Bounding Coordinate    
OR if single point location    
Latitude 42.5236  
Longitude -71.185  
Taxonomic Protocols
Organisms studied
Methods:YSI 6200 data sondes were deployed vertically in a pool deep enough to contain water during dry conditions. The sonde was deployed in a PVC tube, which was attached to ree-bar driven into the stream bed. The PVC tube had holes drilled to allow adequate water circulation. Dissolved oxygen measurements are of poor quality because the the bottom of the pool was often filled in with detritus following intermediate sized storms, leading to anoxic conditions. To alleviate this problem, the PVC tube was raised 10.1 cm on 7/16/03. The file for 2001 includes the raw depth measurement (RAWYSI_Depth), as well as the depth measurement corrected to the YSI depth after the change in tube height (YSI_Depth_STD) and for which the rating curve has been standardized.

The PVC tube was surveyed upon original deployment in 2001 and resurveyed in 2002 to ensure that elevation did not change during winter ice period. No change was detected. No evidence of change has been noted through 2006 based on discharge measurements. See discussion below for development of the discharge-stage relationship.

Recalibration of oxygen, pH, conducitivty and depth was performed roughly every 4-6 weeks. Instrument drift during deployment periods was not significant.

ADDITIONAL RESEARCH LOCATION COORDINATES: In addition to the decimal degree coordinates given above, locations are also given here in Massachusetts State Plane coordinates. The stream is called SawMill Br. and is located in Burlington MA. Small amounts of forest remain (~14% in 1999), much of which is along the stream channel near the gaging site.

YSI-SB 225840 919310

Dissolved oxygen concentrations generally reflect water column levels. However, due to the position of the sonde, detritus periodically covered the bottom of the sondes where the D.O. probe is located, leading to anoxic conditions. It is likely that low D.O. levels reflect benthic conditions.

Velocity measurements were made using a Marsh McBirney current meter and starting in 2009 with a Sontek Flowtracker. Discharge estimates in Saw Mill are based on a power rating curve that contains measurements up to a stage depth of 1.2 meters, which is above bankfull stage. Rating curve has an R2 of 0.89 using 40 measurements between 2001 and 2009. The rating curve has not noticeably changed over the period. Prior to 2007, stage was measured with various other instruments (YSI, Sigma depth sonde, HOBO). All files in this series (2001-2009) are now standardized to HOBO depth. The rating curve is based on the standardized HOBO depth's (and actual HOBO depths since 2007).

Discharge rating curve :
Discharge (l/s) = 889.65*depth^5.8788
where depth is Adj_HOBO_Depth

Several depth are included in this file to allow comparison with earlier file version. RAWYSI_Depth is the depth measured by the YSI and is used by an initial, preliminary rating curve. YSI_Depth_STD is depth adjusted to standardize for the change in stilling well depth in July 2003. The column Depth_Device is included when combining files from several years, over which several different devices were used to calculate depth. Depth_STD is the depth that is standardized across all measurement devices so that a single rating curve can be applied. The rating curve is standardized to the Hobo depth measurements, which were started in 2006. The difference between Hobo data logger depth measurements and YSI data logger depth measurements (YSI_DEPTH_STD) is 0.211m
(StandardizedHoboDepths = YSI_Depth_STD + 0.21)

Also, at times depth and discharge may be periodically erroneous due to leaf pack accumulation at a riffle downstream causing backup. We remove this whenever we visit the site. Generally we believe the depth error is on the order of 2-4 centemeters. The depth data have not been corrected for errors associated with temporary debris dams.

OLD RATING CURVE ( prior to December 2009 revision):
Discharge measurements in Saw Mill are based on a power rating curve that contains measurements up to a depth of 0.6m (using the column RAWYSI_Depth). Flows above this amount are estimated using a linear extrapolation using the six measurements with the highest flow. Thus flows determined from levels greater than 0.6m are approximate (roughly 1% of the readings in 2001 deployment period). Rating curve below 0.6m is based on a power relationship with an R2 = 0.98. Measurements are based on 12 measurements taken between 2001 and 2003.

When stage in SawMill Br. is less than 0.6m :
Discharge (l/s) = 1245.2 (depth) 4.782

When stage in SawMill Br. is greater than 0.6m :
Discharge (l/s) = 560.7 (depth) 229.8

Data Table

Variable Name Variable Description Units Measurement Scale Code Information Number Type DateTime Format Missing Value Code Missing Value Code Explanation
Date date (yyyy-mm-dd)   datetime     yyyy-mm-dd NA NA = not available
Time time (hh:mm:ss) 24 hour   datetime     hh:mm:ss NA NA = not available
Temp water temperature (oC) celsius interval   real   NA NA = not available
SpCond specific conductivity (mS/cm) millisiemenPerCentimeter ratio   real   NA NA = not available
DO% dissolved oxygen percent of saturation (%) percent ratio   real   NA NA = not available
DOConc dissolved oxygen concentration (mg/l) milligramPerLiter ratio   real   NA NA = not available
pH log of the H+ ion concentration dimensionless ratio   real   NA NA = not available
RAWYSI_Depth stage height measured by YSI (m) meter ratio   real   NA NA = not available
YSI_Depth_STD stage height measured by YSI (m) (standardized) meter ratio   real   NA NA = not available
OLD-Discharge discharge using OLDYSI_Depth and earlier rating curve (l/s) literPerSecond ratio   real   NA NA = not available
Device_Depth depth measurement device used to determine discharge   nominal YSI = YSI depth sonde | SIGMA = Sigma autosampler depth sonde | TEMP_HOBO = HOBO depth sonde deployed in temporary stilling well | HOBO = HOBO depth sonde deployed in permanent stilling well     NA NA = not available
StandardizedHoboDepths depth standardized to rating curve using HOBO depths meter ratio   real   NA NA = not available
Discharge discharge literPerSecond ratio   real   NA NA = not available