MassDEP requires that outdoor water use restrictions be implemented when Ipswich River streamflow drops below certain trigger points. The aim of the restrictions is to reduce water consumption during periods of low streamflow, making more water available to sustain fish and aquatic life. MassDEP is able to require this by adding special conditions to the Town's water withdrawal permit. Many communities in the Ipswich River basin have the same or similar restrictions.
The restrictions are not required throughout the year, only May 1st through Septmeber 30th depending on streamflow levels. Restrictions implemented due to low streamflow apply to all water users, including public water customers and private well owners. During the last permit review, MassDEP added a condition that required either the restrictions we currently have apply to everyone or more stringent restrictions would apply to public water customers. Town Meeting voted to include private wells in the stream flow based restrictions in May 2006 and the bylaw was approved by the Attorney General the same year.
The need for the restrictions is based on flow measurments taken at a gauge station located just downstream of the dam near Foote Brother's Canoe. The gauge has been in use since 1930 so there are many years worth of historical data. We've compiled a graph that shows the current average daily flow, historical flow information and the restriction trigger points. The chart is updated automatically when the flow data is published by USGS. Looking back through the historical record for the gauge, there is only one year since 1930 that would not have required a mandatory restriction. They typically start around July 1st and end in late September or early October. The mandatory restrictions began very early in 2015 and 2016 due to the drought.
One question that comes up on a regular basis is why does the Town allow development if there are water use restrictions every summer. The answer is that the restrictions limit "non-essential" outdoor use, not essential use. Several conditions in the withdrawal permit do limit long-term growth but the annual water restrictions do not.
When average daily Ipswich River stream flow drops below 70 cubic feet per second (cfs) at the Ipswich Gauge for three consecutive days between May 1st and September 30th we are required to implement a Voluntary Outdoor Water Restriction. Water users are asked to limit non-essential outdoor water use to before 9 AM or after 5 PM each day.
When flow drops even further, below 52.5 cfs, a mandatory restriction is implemented. Non-essential outdoor use is limited to hand-held devices only prior to 9 AM or after 5 PM each day. Use of an irrigation system at anytime is prohibited.