Last winter we noticed more water was being used in the middle of the night when the pumps were running than when they were off.  This observation could be explained by the master meters at the water sources recording 5% too much water.  For the past several years we had calibrated the master meters using a turbine meter attached to a fire hydrant near the stations and compared the amount of water flowed through the meter and the station.

This summer we assembled a truck mounted flow meter to check the master meters.  The truck mounted meter uses magnetic fields to sense the velocity of the water passing through a tube with a known diameter. The meter is accurate to 0.3% and is much more accurate than the station meters.  We found the venturi meter at the North Street station was over-registering by 4.1% and Perkins Row by 5.0%.  We are required to keep our Unaccounted for Water below 10% so these metering errors can be a large portion of UAW.

May 1st marks the beginning of the Massachusetts Department of Environmental Protection's summer regulatory period. Our water withdrawal permit requires us to implement outdoor water use restrictions when Ipswich River stream flow falls below certain levels from May 1st through September 30th. The permit also restricts the amount of water we can pump during this period to an average of 0.55 million gallons per day.

Stream flow is measured at the United States Geological Survey's gauge station located just downstream of the dam near Foote Brothers Canoe Rental in Ipswich. 

A voluntary outdoor water use restriction is required if the average daily stream flow at the Ipswich Gauge drops below 70 cubic feet per second for three consecutive days. If the average daily stream flow continues to drop and falls below 52.5 cubic feet per second for three consecutive days then a mandatory restriction is required. The restrictions stay in effect until stream flow recovers and is above the trigger point for at least 10 consecutive days.