E. coli levels generally good on local rivers

Water quality testing on the Souhegan and Merrimack rivers began last week for the 21st year by volunteers with the Souhegan Watershed Association and Lower Merrimack River Local Advisory Committee.

Thirty volunteers will monitor their sites every two weeks during summer. Watson Park in Merrimack will be monitored every week, and results will be posted at the park.

E. coli levels were generally within acceptable levels for swimming on both rivers with one exception. On the Souhegan, the Amherst canoeport on Boston Post Road had an E. coli level of 129.6, slightly higher than the acceptable level of 126.

Watson Park in Merrimack was 105.0. This is an acceptable level for most people, but a bit too high for small children or people with compromised immune systems. The Horseshoe in Wilton was 49.6, an excellent level.

Levels lower than 88 are excellent; between 88 and 126 is acceptable for swimming, but susceptible bathers could experience problems. Levels higher than 126 aren’t recommended for swimming. Swimmer’s ear and gastrointestinal problems may occur at those levels.

The Souhegan had excellent E. coli levels from the headwaters in Ashburnham to downtown Milford. From there to the mouth of the river in Merrimack, E. coli levels increased, but stayed within acceptable limits.

The Merrimack River had very low E. coli counts. This has been true in recent years as the river has cleaned up. The highest level on the river between Manchester and Tyngsborough, Mass., was 48 measured at the boat ramp at Thorntons Ferry, and this was probably the influence of the inflow from the Souhegan River just upstream. This is an excellent level.

Another test is for dissolved oxygen. This test generally indicates the health of the river for fish, animals and habitat. These levels were excellent, but normal for this time of year. Dissolved oxygen levels diminish as the summer goes along and the weather heats up and flow levels decrease. Past years have shown both rivers to be in good health and improving.

The levels of pH show the effects of acid rain, but levels currently are in the normal range, just slightly acidic on both rivers.

Both rivers are running slightly higher than normal because of recent rains. Many volunteers had difficulty getting to their traditional spot to collect the water samples because of the higher water flow. Still, it was a beautiful beginning to get out on the river in the morning and several of the volunteers saw animals and bird. Deer, beaver, blue heron and others were spotted. Unfortunately, there was lots of trash for volunteers to pick up.

There is always a need for additional volunteers. Anyone interested can contact email georgemay@comcast.net.

Also, there is a need to do macroinvertibrate testing, which would make a great summer project for a Boy or Girl Scout or for a school project.

Volunteers, many of whom have been with the program for years, adopt a site and test every other Tuesday morning. They take samples to wastewater treatment plants in Greenville, Milford, Merrimack, Manchester and Nashua, where the samples are processed by certified professionals. The next test will be June 27.

For information, visit www.souheganriver.org.

– Submitted by

Souhegan Watershed Association

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