​Souhegan and Merrimack E. Coli Levels: Generally Good​

MERRIMACK, NH — Water quality testing on the Souhegan River and Merrimack River began again on Tuesday for the 21st year by volunteers with the Souhegan Watershed Association and Lower Merrimack River Local Advisory Committee. Thirty different volunteers will monitor their site every two weeks during the summer and the results will be reported here and more fully on the SWA website at souheganriver.org, according to a press statement. Watson Park in Merrimack will be monitored every week and those results will be posted at the park and also on Facebook.

E. coli levels where people swim 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 126 level for acceptable swimming. 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 are not recommended for swimming. Swimmers ear and gastrointestinal problems may occur at those levels.

The Souhegan had excellent E. coli levels from the headwaters in Ashburnham till downtown Milford. From here to the mouth of the river in Merrimack E. coli levels increased but generally 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 entire river between Manchester and Tyngsborough was 48 measured at the boat ramp at Thorntons Ferry and this was probably the influence of the inflow from the just upstream Souhegan River. This is an excellent level.

Another test is for dissolved oxygen. This test generally indicates the general 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 go down. Past years have shown both rivers to be in good health and still improving.

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

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

There is always a need for additional volunteers. Anyone interested can contact GeorgeMay@comcast.net to see if there is a site nearby. Also there is a need to do macroinvertibrate testing that would make a great summer project for a boy/girl scout or school project.

The rivers will be tested again every two weeks during the summer. Thirty volunteers, many of whom have been with the program for many years, adopt a site and test every other Tuesdaymorning and carry the samples to the local wastewater treatment plants in Greenville, Milford, Merrimack, Manchester and Nashua where the samples are processed by certified professionals. More information is available on the SWA website.

The next test will be on June 27.

Results on June 13, 2017

SOUHEGAN RIVER SITES:

1. Billy Ward Pond, Ashburnham #1 3.1; #2 1.0
2. SoR 333 Water Loom Pond, New Ipswich 41
3. SoR 320 Highbridge, New Ipswich 21.8
4. SoR 309 Above Greenville Mill Pond, Greenville 27.5
5. SoR 296 Downtown Greenville upstream of WWTP 48.7
6. SoR 291 Green Bridge off Rte 31 below Greenville WWTP 34.1
7. SoR 218 Below the Horseshoe, Wilton 49.6
8. SoR 210 Downtown Wilton 57.3
9. SoR 201 Pine Valley Mill, West Milford NA
10. SoR 170 Behind Hayward Field, West Milford 67.7
11. SoR 155 Souhegan Valley Boys and Girls Club, Milford 102.2
12. SoR 146 Swing Bridge, Milford 129.6
13. SoR 133 Riverside Cemetery, Milford 81.3
14. SoR 130 Behind Lorden Plaza, Milford 125.9
15. SoR 122 Amherst Country Club 83.6
16. SoR 116 Amherst Conservation land Fairway Road, Amherst NA
17. SoR 095 Boston Post Road Canoeport, Amherst 129.6
18. SoR 057 Indian Ledges, Merrimack 96.0
19. SoR 034 Turkey Hill Bridge, Merrimack 105.0
20. SoR 001 Watson Park, Merrimack 105.0

MERRIMACK RIVER SITES:

1. Mer 600 Above Amoskeag Dam, Manchester 24.6

2. Mer 590 Arms Park, Manchester 12.2

3. Mer 570 Goffs Falls, Litchfield NA

4. Mer 560 Depot Street, Merrimack 27.9

5. Mer 550 Upstream of Souhegan River, Merrimack NA

6. Mer 540 Thorntons Ferry, Merrimack 48.0

7. Mer 530 Greeley Park, Nashua 41.4

8. Mer 520 Taylors Falls Bridge, Nashua 34.1

9. Mer 510 Sagamore Bridge, Hudson 41.4

10. Mer 500 Pheasant Lane Mall, Hudson NA

11. Mer 490 Upstream of Tyngsboro Bridge 18.9

Flow on Upper Souhegan was 183 CFS and expected flow for that date is 90

Flow on Lower Souhegan was 285 CFS and historic flow for that date is 132

Flow on Merrimack was 7500 CFS and historic flow for that date is 3620

RAINFALL – Weather clear, warm, no rain

Submitted by George May.