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 good quality because detritus did not accumulate in the bottom of the pool (unlike our suburban site). 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. See discussion below for development of the discharge-stage relationship. Recalibration was performed roughly every 4-6 weeks. Instrument drift during deployment periods was not significant.

RESEARCH LOCATION: Locations are in Massachusetts State Plane coordinates. The site is located on the Ipswich R. mainstem at North Reading, just upstream of Rt. 28 (~48 km2 drainage area). The contributing area includes a large component of urban land use, but with significant wetland area remaining, especially in floodplain. Large amounts of water withdrawals occur upstream.
STATION STATE X STATE Y
YSI-IR 232080 923630

NOTES AND COMMENTS:
Discharge measurements in the Ipswich R. at North Reading are based on a linear rating curve that contains measurements up to a depth of 0.8m. Flows above this amount are estimated using a linear extrapolation. Thus flows determined from levels greater than 0.475m are approximate (4 % of the readings in 2001 deployment period).Rating curve had an R2 = 0.99. Measurements are based on 8 measurements taken in 2001.
Dissolved oxygen concentrations reflect water column levels.
NA refers to data not available.