Data: ​River E. Coli Results 'Excellent'

By George May

MERRIMACK, NH — Flows are ameliorating on both rivers right now. The Merrimack River has been higher than its historic average since testing began at the beginning of the summer. But now that the constant rains have stopped, it’s come down from very high to just somewhathigh. It’s flowing at a little over 3,000 cubic feet per second; its historic average for this date is just over 2000. That’s 50 percent higher than it should be. The Souhegan River is telling the story however. The upper stretch of the river from Ashburnham to Wilton is now below its predicted flow. This stretch is smaller, rocky with fewer small tributaries and very subject to changes in rainfall. The lower stretch to Merrimack is still 25 percent above the predicted flow, but coming down. Both rivers are on their way to historic averages. Anyone can check river levels any time at www.waterdata.usgs.gov/nh/nwis/current/?type=flow&group_key=basin_cd.

Water temperatures are still staying in the healthy range for fish and wildlife. The Merrimack has come up to 24 celsius (75F); the Souhegan to 21C (70F). Generally cooler is better; it can contain more oxygen. Oxygen levels on both rivers are in the very healthy range also – in the 7’s on the Merrimack and in the 8’s on the Souhegan. These numbers will drop as the summer progresses but have always remained within a healthy range. There is more info about DOs on the SWA website.

E. coli results for both rivers look excellent – probably a result of the nice weather recently. A rainstorm on Saturday with almost a half inch of rain could have brought up E. coli counts, but it never showed up in the results. No sites on either river exceeded the 406 average that the state considers polluted. A few spots on the Souhegan - where population increases - were a bit high but well below the 406 limit. The Swing Bridge in Milford had the highest count on the Souhegan – 214, but that is not bad considering.

Swimming spots on the rivers all tested below the 88 limit that is recommended for beaches. The Horseshoe in Wilton, Indian Ledges and Watson Park in Merrimack were excellent. The Boston Post Road Canoeport in Amherst was a bit high at 130 but acceptable for adults without health problems. Goff’s Falls on the Merrimack, the only usual swimming spot on our section of the Merrimack, tested excellent as well – though it should be noted that there may be other pollutants in that river that we do not test for.

See the attached chart of the E. coli levels for the Souhegan so far this season: The river runs upstream on the left to downstream on the right.

You can see that we started out with high levels that have come down to excellent levels in the last two tests. Probably a result of all the earlier rains washing whatever pollution off the banks and then relatively dry, clean weather following.

The most interesting observation this week came from the monitor at Goff’s Falls on the Merrimack watching two peregrine falcons pigeon hunting for their breakfast. There have been falcons in Manchester for the last several years.

We still have two sites in Merrimack available for a volunteer to adopt.

All of the DO, pH and E.coli tests are performed by certified technicians in the labs at the Milford, Merrimack, Manchester, and Nashua wastewater treatment plants.

The next test will be on Tuesday, July 23, and the results available the next day.

Here are the results for this week:

E-COLI MONITORING RESULTS FOR TESTS TAKEN ON JULY 9, 2019

SOUHEGAN RIVER SITES:

1. Billy Ward Pond, Ashburnham #1 3.1; #2 1.0
2. SoR 333 Water Loom Pond, New Ipswich 3.1
3. SoR 320 Highbridge, New Ipswich 12.2
4. SoR 309 Above Greenville Mill Pond, Greenville 23.1
5. SoR 296 Downtown Greenville upstream of WWTP 14.8
6. SoR 291 Green Bridge off Rte 31 below Greenville WWTP 22.8
7. SoR 218 Below the Horseshoe, Wilton 35.9
8. SoR 210 Downtown Wilton 71.1
9. SoR 201 Pine Valley Mill, West Milford 53.8
10. SoR 170 Behind Hayward Field, West Milford NA
11. SoR 155 Souhegan Valley Boys and Girls Club, Milford 101.9
12. SoR 146 Swing Bridge, Milford 214.2
13. SoR 133 Riverside Cemetery, Milford 127.3
14. SoR 130 Behind Lorden Plaza, Milford 125.9
15. SoR 122 Amherst Country Club 114.5
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 75.4
19. SoR 034 Turkey Hill Bridge, Merrimack NA
20. SoR 001 Watson Park, Merrimack 52.1

MERRIMACK RIVER SITES:

• Mer 600 Above Amoskeag Dam, Manchester 53.7
• Mer 590 Arms Park, Manchester 14.8
• Mer 580 Upstream of Piscataquog River, Manchester NA
• Mer 570 Goffs Falls, Litchfield 55.6
• Mer 560 Depot Street, Merrimack 50.4
• Mer 550 Upstream of Souhegan River, Merrimack NA
• Mer 540 Thorntons Ferry, Merrimack 93.3
• Mer 530 Greeley Park, Nashua 34.1
• Mer 520 Taylors Falls Bridge, Nashua 26.5
• Mer 510 Sagamore Bridge, Hudson 28.5
• Mer 500 Pheasant Lane Mall, Hudson NA
• Mer 490 Upstream of Tyngsboro Bridge 46.4
• Mer 600 Above Amoskeag Dam, Manchester 7.86
• Mer 590 Arms Park, Manchester 8.14
• Mer 580 Upstream of Piscataquog River, Manchester NA
• Mer 570 Goffs Falls, Litchfield 7.77
• Mer 560 Depot Street, Merrimack 7.86
• Mer 550 Upstream of Souhegan River, Merrimack NA
• Mer 540 Thorntons Ferry, Merrimack 7.51
• Mer 530 Greeley Park, Nashua 7.94
• Mer 520 Taylors Falls Bridge, Nashua 7.95
• Mer 510 Sagamore Bridge, Hudson 7.97
• Mer 500 Pheasant Lane Mall, Hudson NA
• Mer 490 Upstream of Tyngsboro Bridge 8.12
• Mer 600 Above Amoskeag Dam, Manchester
• Mer 590 Arms Park, Manchester
• Mer 580 Upstream of Piscataquog River, Manchester
• Mer 570 Goffs Falls, Litchfield
• Mer 560 Depot Street, Merrimack
• Mer 550 Upstream of Souhegan River, Merrimack
• Mer 540 Thorntons Ferry, Merrimack 6.44
• Mer 530 Greeley Park, Nashua
• Mer 520 Taylors Falls Bridge, Nashua
• Mer 510 Sagamore Bridge, Hudson 6.82
• Mer 500 Pheasant Lane Mall, Hudson
• Mer 490 Upstream of Tyngsboro Bridge

Flow on Upper Souhegan was 39 CFS. Expected flow for that date is 59

Flow on Lower Souhegan was 80 CFS. Historic flow for that date is 64

Flow on Merrimack was 3120 CFS. Historic flow for that date is 2120

RAINFALL: .046” Saturday; otherwise clear

Temperature: Souhegan 21C Merrimack 24C

DO MONITORING RESULTS FOR TESTS TAKEN ON JULY 9, 2019

SOUHEGAN RIVER SITES:

1. Billy Ward Pond, Ashburnham #1 7.47 ; #2 7.61
2. SoR 333 Water Loom Pond, New Ipswich 6.91
3. SoR 320 Highbridge, New Ipswich 8.12
4. SoR 309 Above Greenville Mill Pond, Greenville 8.11
5. SoR 296 Downtown Greenville upstream of WWTP 8.28
6. SoR 291 Green Bridge off Rte 31 below Greenville WWTP 8.33
7. SoR 218 Below the Horseshoe, Wilton 9.43
8. SoR 210 Downtown Wilton 9.32
9. SoR 201 Pine Valley Mill, West Milford 8.36
10. SoR 170 Behind Hayward Field, West Milford NA
11. SoR 155 Souhegan Valley Boys and Girls Club, Milford 7.60
12. SoR 146 Swing Bridge, Milford NA
13. SoR 133 Riverside Cemetery, Milford 8.00
14. SoR 130 Behind Lorden Plaza, Milford 8.06
15. SoR 122 Amherst Country Club 7.88
16. SoR 116 Amherst Conservation land Fairway Road, Amherst NA
17. SoR 095 Boston Post Road Canoeport, Amherst 7.29
18. SoR 057 Indian Ledges, Merrimack 8.49
19. SoR 034 Turkey Hill Bridge, Merrimack NA
20. SoR 001 Watson Park, Merrimack 8.80

MERRIMACK RIVER SITES:

SELECTED pH RESULTS FOR JULY 9, 2018

SOUHEGAN RIVER SITES:

1. Billy Ward Pond, Ashburnham #1 , #2
2. SoR 333 River Road above Water Loom Pond, New Ipswich
3. SoR 320 Highbridge, New Ipswich
4. SoR 309 Above Greenville Mill Pond, Greenville
5. SoR 296 Downtown Greenville upstream of WWTP
6. SoR 291 Green Bridge off Rte 31 below Greenville WWTP
7. SoR 218 Below the Horseshoe, Wilton 6.87
8. SoR 210 Downtown Wilton 6.99
9. SoR 201 Pine Valley Mill, West Milford 6.66
10. SoR 170 Behind Hayward Field, West Milford
11. SoR 155 Souhegan Valley Boys and Girls Club, Milford 6.58
12. SoR 146 Swing Bridge, Milford
13. SoR 133 Riverside Cemetery, Milford 6.62
14. SoR 130 Behind Lorden Plaza, Milford 6.46
15. SoR 122 Amherst Country Club 6.70
16. SoR 116 Amherst Conservation land Fairway Road, Amherst
17. SoR 095 Boston Post Road Canoeport, Amherst 6.51
18. SoR 057 Indian Ledges, Merrimack
19. SoR 034 Turkey Hill Bridge, Merrimack
20. SoR 001 Watson Park, Merrimack