Bacteria Levels in Rivers Return to Lower Levels

Submitted by George May, creator of the water-testing program for the Souhegan River watershed. He is a resident of Merrimack.

After periods of heavy rain in recent weeks that increased river flows and bacteria levels in the Merrimack and Souhegan Rivers, volunteers went out Tuesday morning to collect new samples. They found that both rivers have returned to more expected flows and more expected levels of pollution.

Flows actually exceeded normal flows for this time of year by a factor of three, but the rivers have returned to their usual level on the banks. Two weeks ago the rivers were flowing at six times their historical averages and appeared much higher on the banks. The Merrimack is slowly coming down after the heavy rains of the last month. The Souhegan is a much smaller river and is coming down quicker. At the time of the test the Merrimack was flowing at 6730 cubic feet per second – over 50,000 gallons per second.

Interestingly, the past month’s heavy rains damaged the flash boards at the Pawtucket Dam inLowell and repairs will require the Merrimack to be lowered by about five more feet in elevation at least through the end of July. The Pawtucket Dam ponds the river up all the way to Reeds Ferry in Merrimack. This lowering will affect boating in the Nashua area as more rocks are exposed. Damage of this sort is usual but could be prevented by replacing the flashboards with a bladder system like the one being installed on Jackson Falls Dam inNashua and that the local advisory committee has called for.

E. coli levels on the Souhegan River were similar to what has been seen in recent summers. The upper stretch of the river tested OK. The middle section from Downtown Wilton toMerrimack had high levels of bacteria. And the lower section through Merrimack returned to an acceptable level. The bacteria levels came way down from tests two weeks ago after the heavy rains. The middle section of the river, through Milford and Amherst, slows down and meanders back and forth through sandy soils and the bacteria counts are often naturally higher than in the rest of the river. Counts in this section were in the 150-200 range. Counts higher than 88-126 can cause ear and eye infections and gastrointestinal problems for swimmers.

Watson Park in Merrimack tested at 35.9. This swimming hole is being tested twice weekly this summer and the results are posted at the park. Other popular swimming spots were the Horseshoe in Wilton at 119.8, slightly high, the Amherst Canoeport at Boston Post Road at 166.4, Indian Ledges in Merrimack at 79.4, and Turkey Hill Bridge in Merrimack at 58.3. 

The Merrimack River tested at a very acceptable level all the way between Manchester and Tyngsborough. The highest level, only 38.9, was seen at Goffs Falls in Bedford, another popular spot for swimmers. Typically the Merrimack has very low bacteria counts throughout the summer unless after heavy rainstorms.

There are additional sites that need monitors or backups. If you are willing to volunteer 30 minutes collecting a water sample every other Tuesday morning, contact Karen Mattor atswawatertesting@gmail.com.

Additional tests are also done on three tributary brooks in New Ipswich and those results are available from the conservation commission.

All of the observations are done by the monitors at the river; all of the biological tests are performed by certified personnel in the labs at the wastewater facilities of Manchester,Nashua, Merrimack, and Milford.

Here the results for all of the E. coli tests done at all of the sites on both rivers on July 16:

E-COLI MONITORING RESULTS FOR TESTS TAKEN ON JULY 16, 2013 

SOUHEGAN RIVER SITES:

1. Billy Ward Pond, Ashburnham  #1- <1, #2- 2.0
2. SoR  333  River Road above Water Loom Pond, New Ipswich  NA
3. SoR  320  Highbridge, New Ipswich  NA
4. SoR  309  Above Greenville Mill Pond, Greenville  135.4
5. SoR  296  Downtown Greenville upstream of WWTP  56.5
6. SoR  291  Green Bridge off Rte 31 below Greenville WWTP   45.5
7. SoR  218  Below the Horseshoe, Wilton   119.8
8. SoR  210  Downtown Wilton  178.2
9. SoR  201  Pine Valley Mill, West Milford   275.5
10. SoR  170  Behind Hayward Field, West Milford  NA 
11. SoR  155  Souhegan Valley Boys and Girls Club, Milford  178.5
12. SoR  146  Swing Bridge, Milford  178.9
13. SoR  133  Riverside Cemetery, Milford  146.7  
14. SoR  130  Behind Lorden Plaza, Milford  155.3
15. SoR  122  Amherst Country Club  89.1
16. SoR  116  Amherst Conservation land Fairway Road, Amherst   201.4
17. SoR  095  Boston Post Road Canoeport, Amherst  166.4  (DUP 178.5)
18. Sor   070   Seaverns Bridge, Merrimack 77.1 (DUP 70.8)
19. SoR  057  Indian Ledges, Merrimack  79.4
20. SoR  034  Turkey Hill Bridge, Merrimack  58.3   
21. SoR  001   Watson Park, DW Hwy, Merrimack  35.9

MERRIMACK RIVER SITES:

1.      Mer  600  Above Amoskeag Dam, Manchester  24.1

2.      Mer  590  Arms Park, Manchester  25.3

3.      Mer  570  Goffs Falls, Litchfield  38.9

4.      Mer  560  Depot Street, Merrimack   NA

5.      Mer  550  Upstream of Souhegan River, Merrimack  NA

6.      Mer  540  Thorntons Ferry, Merrimack  NA

7.      Mer  530  Greeley Park, Nashua  35.5

8.      Mer  520  Taylors Falls Bridge, Nashua   43.9

9.      Mer  510  Sagamore Bridge, Hudson  18.1

10.  Mer  500  Pheasant Lane Mall, Hudson   NA

11.  Mer  490  Upstream of Tyngsboro Bridge  22.1