Lots of Water, Moderately Poor E

July 11, 2017

STORM DRAINS INCREASE E. COLI

Water quality monitors had to go out in drizzly rain and negotiate slippery rocks on Tuesday morning to collect river samples this week. What they found were moderately high E. coli counts in the downtown sections of Wilton and Milford, where storm drains were draining runoff into the Souhegan River. E. coli levels remained high through Milford and Amherst but moderated to acceptable levels finally in Merrimack. The popular swimming spot at Watson Park in Merrimack was an acceptable level of 88. All of the other spots where people swim were also acceptable with the exception of the Boston Post Road Canoeport in Amherst. The level there usually tests high and this week was no exception – the level here was 225, higher than an acceptable level for swimming.

An unusual leap in E. coli to dangerous levels was recorded downstream of Kaley Park in Milford. This appears to have been caused by a singular event and the program is investigating.

All of the Souhegan River upstream of Wilton had excellent E. coli levels. That is almost always the case.

E. coli levels below 88 are completely safe for swimming; below 126 is OK for most people, but small children or those with compromised immune systems may experience gastrointestinal problems and swimmers eye or ear. Higher than 126 is not recommended; and higher than 406 is dangerous.

The Merrimack River between Manchester and Tyngsborough had acceptable E. coli levels all the way with one exception. The test site just below where the Souhegan River empties in showed the effects of that river’s higher counts. The level here increased to 114 from surrounding levels that were half that. However, the larger river quickly absorbed and diluted that pollution and returned to excellent E. coli levels all the way to Tyngsborough. The Merrimack River typically has excellent E. coli levels.

Dissolved oxygen levels are also tested. This test is a better indicator of the general health of the river itself. Worsening dissolved oxygen showed up in the lower stretch of the river upstream of Tyngsborough. Up to this point in the summer DO levels were above 8, an excellent level. This week a couple of the sites tested in the 6-7 range that bears watching and may be due to a refilling of the dam in Lowell. The Souhegan River had excellent DO levels throughout its length.

Monitors also reported lots of animals, bugs, and birds out along the rivers – Great Blue Herons, especially, were seen at several sites on both the Merrimack and Souhegan Rivers. The rivers will be tested again on July 25. Thirty volunteers, many of whom have been with the program for many years, adopt a site and test every other Tuesday morning and carry the samples to local wastewater treatment plants in Greenville, Milford, Merrimack, Manchester and Nashua where the samples are processed by certified professionals. More information is available at www.souheganriver.org. Additional volunteers are always welcomed.

Here are the individual results for E. coli for this week:

E-COLI MONITORING RESULTS FOR TESTS TAKEN ON JULY 11, 2017

SOUHEGAN RIVER SITES:

1. Billy Ward Pond, Ashburnham #1 2.0; #2 1.0 2. SoR 333 Water Loom Pond, New Ipswich 7.5 3. SoR 320 Highbridge, New Ipswich 25.6 4. SoR 309 Above Greenville Mill Pond, Greenville 416.0 5. SoR 296 Downtown Greenville upstream of WWTP 32.7 6. SoR 291 Green Bridge off Rte 31 below Greenville WWTP 38.4 7. SoR 218 Below the Horseshoe, Wilton 65.0 8. SoR 210 Downtown Wilton 214.3 9. SoR 201 Pine Valley Mill, West Milford 90.8 10. SoR 170 Behind Hayward Field, West Milford 160.7 11. SoR 155 Souhegan Valley Boys and Girls Club, Milford NA 12. SoR 146 Swing Bridge, Milford 260.3 13. SoR 133 Riverside Cemetery, Milford 686.7 14. SoR 130 Behind Lorden Plaza, Milford 547.5 15. SoR 122 Amherst Country Club 387.3 16. SoR 116 Amherst Conservation land Fairway Road, Amherst NA 17. SoR 095 Boston Post Road Canoeport, Amherst 224.7 18. SoR 057 Indian Ledges, Merrimack 98.8 19. SoR 034 Turkey Hill Bridge, Merrimack 83.3 20. SoR 001 Watson Park, Merrimack 88.4

MERRIMACK RIVER SITES:

1. Mer 600 Above Amoskeag Dam, Manchester 42.8 2. Mer 590 Arms Park, Manchester 75.9 3. Mer 580 Upstream of Piscataquog River, Manchester NA 4. Mer 570 Goffs Falls, Litchfield 55.6 5. Mer 560 Depot Street, Merrimack 56.3 6. Mer 550 Upstream of Souhegan River, Merrimack 46.5 7. Mer 540 Thorntons Ferry, Merrimack 114.5 8. Mer 530 Greeley Park, Nashua 61.3 9. Mer 520 Taylors Falls Bridge, Nashua 69.7 10. Mer 510 Sagamore Bridge, Hudson 74.3 11. Mer 500 Pheasant Lane Mall, Hudson NA 12. Mer 490 Upstream of Tyngsboro Bridge 38.3

One additional test was done on Great Brook, Milford. Its results: DO 5.76, pH 6.16, Temp 23C, E coli 118.7

Flow on Upper Souhegan was 42CFS. Expected flow for that date is 41 Flow on Lower Souhegan was 80CFS. Historic flow for that date is 67 Flow on Merrimack was 3180CFS. Historic flow for that date is 1930 RAINFALL: Showers Sat (.16); drizzle during test. Water Temperature: Souhegan 22C Merrimack 22C

DO MONITORING RESULTS FOR TESTS TAKEN ON JULY 11, 2017

SOUHEGAN RIVER SITES:

21. Billy Ward Pond, Ashburnham #1 7.85 ; #2 8.11 22. SoR 333 Water Loom Pond, New Ipswich 7.53 23. SoR 320 Highbridge, New Ipswich 8.03 24. SoR 309 Above Greenville Mill Pond, Greenville 7.63 25. SoR 296 Downtown Greenville upstream of WWTP 7.97 26. SoR 291 Green Bridge off Rte 31 below Greenville WWTP 8.06 27. SoR 218 Below the Horseshoe, Wilton NA 28. SoR 210 Downtown Wilton 8.52 29. SoR 201 Pine Valley Mill, West Milford 8.62 30. SoR 170 Behind Hayward Field, West Milford 7.96 31. SoR 155 Souhegan Valley Boys and Girls Club, Milford NA 32. SoR 146 Swing Bridge, Milford 7.80 33. SoR 133 Riverside Cemetery, Milford 7.97 34. SoR 130 Behind Lorden Plaza, Milford 7.96 35. SoR 122 Amherst Country Club 7.85 36. SoR 116 Amherst Conservation land Fairway Road, Amherst NA 37. SoR 095 Boston Post Road Canoeport, Amherst 7.35 38. SoR 057 Indian Ledges, Merrimack 7.84 39. SoR 034 Turkey Hill Bridge, Merrimack 7.55 40. SoR 001 Watson Park, Merrimack 8.5

MERRIMACK RIVER SITES:

13. Mer 600 Above Amoskeag Dam, Manchester 8.13 14. Mer 590 Arms Park, Manchester 8.43 15. Mer 580 Upstream of Piscataquog River, Manchester NA 16. Mer 570 Goffs Falls, Litchfield 8.05 17. Mer 560 Depot Street, Merrimack 8.02 18. Mer 550 Upstream of Souhegan River, Merrimack 8.0 19. Mer 540 Thorntons Ferry, Merrimack 7.58 20. Mer 530 Greeley Park, Nashua 8.08 21. Mer 520 Taylors Falls Bridge, Nashua 6.92 22. Mer 510 Sagamore Bridge, Hudson 8.06 23. Mer 500 Pheasant Lane Mall, Hudson NA 24. Mer 490 Upstream of Tyngsboro Bridge 6.62