Souhegan Watershed Association

Water Testing Results
Summer 2005

The Souhegan Watershed Association monitors the entire length of the Souhegan River and part of the Merrimack River for their aquatic health. Water samples are tested for pH, phosphorus, dissolved oxygen, temperature, and bacteria. Weather and streamflow information was also recorded when water samples are collected. Previous results, beginning in 1997, are available in reports that can be found in local libraries. Summaries and original results are available here.

This monitoring program is conducted by trained volunteers who believe in cleaner rivers. Financial support for the program comes from donations and special grants. In the past, support has been provided by:

• A NHDES non-point source pollution grant.
• Merrimack Valley Paddlers.
• Amherst Conservation Commission
• Merrimack Conservation Commission
• Wilton Conservation Commission
• Jonathon Rosse
• Ken ButenhofGeorge May

E-Coli Bacteria Counts

Our E-coli samples are prepared and counted by professionals at the local wastewater treatment plants in Greenville, Merrimack, Milford, and Nashua on a volunteer basis. The results are reported as the number of e-coli bacteria colonies observed under a microscope in 100 ml of water. Bacteria levels below 88 colonies per 100 ml. are considered safe for public swimming areas. Anything above that level may cause ear and eye infections, diarrhea or other gastrointestinal problems in a percentage of swimmers. These bacteria numbers being reported are good for only a few days. They do indicate the general health of the river water at a particular moment in time. The next measurement can be considerably different, depending on water level and temperature, and what has recently washed, flowed, or been poured into the river. The current E-coli results this year are available here.

Dissolved Oxygen Measurements

Dissolved oxygen is "breathed" by fish and insects that live in the water. Dissolved Oxygen requirements for different species vary greatly, even if only fish are considered. One of the more sensitive family groups is trout. The lower limit for them is about 5 mg/L (or 5 ppm). The maximum value attainable is called O₂ saturation. The concentration of O₂ equal to the saturation limit in water increases with DECREASING temperature and INCREASING pressure. At 1 atmosphere pressure and 20 degrees centigrade the concentration of saturated O₂ is 9.1 mg/L, while at 1 atmosphere pressure and 25 degrees centigrade O₂ is saturated at 8.2 mg/L. The rate of oxygen usage, the rate of oxygenization (turbulence) and the rate of mixing of the different strata of water all contribute to surface oxygen levels. The simplified conclusion is that adequate oxygen levels indicate a healthy, balanced river habitate.

Cumulative 2005 E-Coli Data

Sept. 6th Description
E. COLI LEVELS DOWN AGAIN ON LOCAL RIVERS

A lack of rain for several days before the next to the last water quality test this season on the Souhegan and Merrimack Rivers helped keep the E. coli bacteria levels to a very acceptable level again this week. Volunteer monitors with the Souhegan Watershed Association and the Lower Merrimack River Local Advisory Committee found river water fairly clean almost everywhere they tested along both rivers.

"When we tested two weeks ago, the rivers were cleaner than we'd ever found before. And this week they're even cleaner. Like the Patriots and Red Sox, we're setting records," said George May, president of the SWA. Much of the reason is the lack of rain to wash pollution into the rivers from storm drains and impervious surfaces such as roads, fields, and parking lots according to May. But he also attributes the cleanliness to people paying more attention to the rivers.

The highest bacteria levels were seen on the Souhegan as usual. Readings through Amherst were above 100, which is higher than the 88 target level that the program looks for. Readings above 88 are not acceptable for public swimming beaches in the state. But both ends of the river had very low readings. The highest reading in the headwaters was 56 at Highbridge in New Ipswich. Low readings continued right through to the Horseshoe, a popular summer swimming hole, which had a reading of 20. And a second reading taken for DNA testing at this site was only 3. At the other end of the Souhegan, in Merrimack, the reading at Indian Ledges was 4. The reading at the Boston Post Road Canoeport near Souhegan High School was 136.

The Merrimack River was extremely clean. The highest reading anyplace between Manchester and Tyngsborough was 28 at the Taylors Falls Bridge, which crosses the river below the mouth of the Nashua River. A number of the sites had readings too low to get an accurate count at the level that the test measures.

The SWA also did an extensive DNA sampling of the Souhegan in the Wilton area this week. Thirteen extra samples were taken to determine the type of bacteria in the water in order to identify sources of pollution coming into the river. This is the third area that has been examined in detail this summer. The bacteria counts are determined at the Merrimack Wastewater Treatment Plant's lab and the DNA identification is done at UMass Boston through a grant from ENSR International.

Both rivers also show the influence of the many dams. The Souhegan dam along Rte 101 on the Milford/Wilton line has been drawn down and the pond is completely empty right now. The Boott Mill Dam in Lowell was drawn down a couple weeks ago but has been closed up again and the Merrimack River is beginning to come back up, but slowly due to the lack of rain. The dams are required to pass a minimum flow at all times to maintain the integrity of the river and protect the fish so it takes a while to recover to normal, full levels. The pond from the Lowell dam backs up to the town of Merrimack.

The flow on the Souhegan was below its historic average for the first time this season. Historically the Souhegan has averaged a flow of 41 cubic feet per second on this date, but it was flowing at 33 CFS. Although the monitors noticed the level dropping all summer long and kept reporting low flows, this week is the first time it has been lower than expected. The Merrimack was higher than its historic average. It was flowing at 2470 CFS, higher than the expected 1445.

The bacteria samples are tested at the Milford, Merrimack, and the Nashua Wastewater Treatment Facilities. The Nashua National Fish Hatchery provides the lab for testing for dissolved oxygen, which is necessary for fish and plant life. The labs at the NH Department of Environmental Services in Concord do phosphorus testing.

August 23rd Description
SOUHEGAN, MERRIMACK RIVERS 'CLEAN AS A WHISTLE'

This week's tests conducted by the Souhegan Watershed Association and Lower Merrimack Local Advisory Committee found both rivers essentially free of E. coli bacteria. George May, SWA president, said, "This is probably the cleanest we've seen both rivers since we began testing nine years ago." May attributed this to the lack of rain for the week before the test and to more care in protecting the rivers.

None of the twelve sites tested on the Merrimack River between Manchester and Tyngsboro came close to the 88 colonies of bacteria per 100 mL of water that the program uses as the target for impure water. This is the reading that the state uses to certify public swimming beaches. A reading higher than 88 would require closing the beach until the reading dropped. The highest reading seen on the Merrimack was at the Taylors Falls Bridge. That was 48. "That's excellent," said May. Several of the sites tested at 0, no bacteria detected at all. The Merrimack normally tests as very clean unless there is rain to wash the bacteria into the river.

The Souhegan also looked very clean this week. The Souhegan is a much smaller river than the Merrimack and shows higher E. coli levels normally. The rocky headwaters in New Ipswich, Greenville, and Wilton usually have very low E. coli counts. And that's what this week's test found. The highest reading was 56 above Greenville Mill Pond.

As the river slows down and meanders through the sandy soils of Milford and Amherst, the E. coli levels build up. And that's what this week's test found here. All of these sites tested above 100.

The bacteria levels usually drop as the Souhegan makes its way through Merrimack to join the Merrimack River. And that's what this week's test found here. The bacteria level at Indian Ledges in Merrimack was 10.

"But these levels are great," said May. "I wish we could see levels like this all the time."

All of the testing is done by volunteers with the program who traipse to the rivers' edge every other Tuesday morning to see what they can find. Not all the time it's pleasant. Nikki Andrews discovered a dead beaver on the water' s edge where she wanted to do the tests near the Pine Valley Mill on the Milford/Wilton line. Another made plans to return later to pick up the huge amount of trash left by fishermen at the Amherst Canoeport on Rte 122. But Doug Waitt discovered a nice stand of Cardinal flowers at his site in New Ipswich.

The bacteria samples are tested at the Milford, Merrimack, and the Nashua Wastewater Treatment Facilities. The Nashua National Fish Hatchery provides the lab for testing for dissolved oxygen, which is necessary for fish and plant life. The labs at the NH Department of Environmental Services in Concord do phosphorus testing.

August 9th Description
LOW WATER IN LOCAL RIVERS

Water quality monitors from the Souhegan Watershed Association and the Lower Merrimack River Local Advisory Committee noted low levels in both the Souhegan River and Merrimack River during their biweekly testing on Tuesday. But the causes of both differ strongly. The Merrimack River is a dam-controlled river and the Boott Mill Dam in Lowell affects the water level as far upstream as Merrimack. The Lowell dam was opened up to lower the pond, which extends up into NH. According to the dam operators the water was lowered in order to repair a capstone on the top of the dam. They expect the work to be completed and the dam put back into normal operations by this weekend. The water level should come back to its usual level - or even slightly higher - within a few days next week. At the time of the test the flow on this stretch of the Merrimack, which is controlled by the releases at the Amoskeag Dam in Manchester, was almost exactly its normal historic average for this date - 1500 cubic feet per second.

Flow on the Souhegan was somewhat higher than its historic average - 52 cfs versus 38 cfs. Several dams on the Souhegan may impede the water flow and so lower the level in certain stretches of the river. But generally the river is reacting to a lack of rain and summertime levels.

E. coli levels on both rivers were generally low in spite of the lower water levels and warmer temperatures. A lack of rain for the three days prior to the tests helped keep the bacteria in check. For the most part the E. coli levels were similar to the tests two weeks ago when weather conditions were similar. The Merrimack again tested very clean for bacteria, even cleaner than two weeks ago. Not a single site on the Merrimack tested higher than the target 88 level that would be satisfactory for a public swimming beach.

The Souhegan is a much smaller, shallower river that shows higher bacteria counts on a regular basis. However, the Souhegan still tested as fairly clean in spite of a few surprises. The Turkey Hill Bridge area in Merrimack came in below 88 colonies of E. coli per 100 mL of water, but that was the only one of the three popular swimming holes. The Horseshoe in Wilton tested at 260, the highest seen at this popular swimming hole. The Boston Post Road Canoeport in Amherst tested at 164, well above the 88-target level but better than often seen at this swimming hole. The highest reading on the Souhegan was 436, a high number, at the Pine Valley Mill in West Milford. The water level at this site was extremely low below the dam on the Wilton/Milford town line. Typically the E. coli readings on the Souhegan are very good in the headwaters in New Ipswich and Greenville; the levels pick up through downtown Wilton and Milford; and then the readings drop to satisfactory levels again in Merrimack. This is the ninth year that SWA has been collecting this water quality data.

Trained volunteers do all of the testing; the bacteria samples are tested at the Milford, Merrimack, and the Nashua Wastewater Treatment Facilities. The Nashua National Fish Hatchery provides the lab for testing for dissolved oxygen, which is necessary for fish and plant life. The labs at the NH Department of Environmental Services in Concord do phosphorus testing.

July 26th Description
LOCAL RIVERS CLEAN AND WARM

Monitors from the Souhegan Watershed Association and the Lower Merrimack River Local Advisory Committee tested the rivers on Tuesday morning and found water temperatures in the mid-seventies and very few E. coli bacteria. They also noted that although the flow on both rivers had dropped quite a bit from the previous test two weeks ago, they were both still higher than the historical averages for this time of year. Flow on the Merrimack was slightly over 2000 cubic feet per second on Tuesday morning. Historically the Merrimack should be flowing at just over 1500 cfs. The Souhegan was flowing at 100 cfs, double its historical average for this date.

Every site except one on the Merrimack River between the Amoskeag Dam in Manchester and the green bridge in Tyngsborough came in at 88 colonies of bacteria or less. These readings are clean enough for a public swimming beach. At Arms Park in Manchester the reading was 108, higher than the 88 target level, but still very clean. This is what the monitoring program has been finding. The Merrimack River is fairly free of bacteria most of the time. It is only when extremely heavy rains overwhelm the sewage treatment plants in Manchester and Nashua that the river becomes dirty. When the sewage treatment plants are overwhelmed, they dump raw sewage into the river from a total of 35 different pipes, and then the E. coli counts leap out of sight. Both cities are under orders from EPA to correct the problem so no untreated sewage ever goes into the river.

A number of the volunteers monitoring the Souhegan were either on vacation or forgot to take their samples. But this was a good week for that to happen. E. coli counts were generally good at the sites monitored along the river. And an additional 16 samples were taken for the DNA monitoring that is being done on this river and this number of extra samples requires superhuman effort on the volunteers at the labs doing the counts. All of these DNA samples were processed at the Merrimack Wastewater Treatment Plant and all of the other samples were split this week between the Milford and Nashua wastewater facilities.

Swimming holes came out pretty good. The Horseshoe in Wilton was 52. Turkey Hill Bridge in Merrimack was 116. The Boston Post Road Canoeport in Amherst was 211, a higher level than indicated for safe swimming. This site is still being studied using DNA samples to determine the source of the continuing pollution.

There is a gauge to measure the level and flow of the Souhegan River just upstream of Wildcat Falls in Merrimack. That gauge began to stutter up and down around 4pm on Monday. At around 8:30pm the river broke loose and began to flow sharply higher. It jumped from 84 cfs to 120 cfs during the night. "For perspective, that's an additional 16000 gallons a minute flowing over the falls. The only explanation we can guess is that the river was blocked above the falls and the blockage gave way all at once. But we're trying to track down what happened," said George May, SWA president. The river flow was back to normal again by 6pm on Tuesday.

July 12th Description
BACTERIA ON LOCAL RIVERS NO PROBLEM

The worst bugs noted by river monitors this week weren't the bacteria. They were the mosquitoes. Bacteria levels on both the Merrimack and Souhegan Rivers were at a low, very acceptable level.

Monitors from the Souhegan Watershed Association and the Merrimack River Local Advisory Committee, who tested the rivers between 5-8am on Tuesday, noted lots of mosquitoes in their written reports this week. Trying to swat mosquitoes and perform the tests carefully kept the monitors busier than they wanted to be. Monitors also noted that the water looked clearer than earlier in the summer. The river levels are still fairly high so there is good flow throughout. Somewhat cooler temperatures may have also helped to clarify the water. Temperatures of both the air and water were down about 5 degrees Celsius from two weeks ago. Air temperature was in the 63 degree Fahrenheit range and the water temperature was 68F. Flow on the Souhegan was 256 cubic feet per second and the historic average for this date is 65 cfs. Flow on the Merrimack was 7350 cfs and its historic average is 1900. There had been some rain to wash bacteria into the rivers three days before the tests, but generally the bacteria live for only three days. All of these factors seem to have contributed to generally clean rivers this week.

The Merrimack River may not have been quite as clean as two weeks ago. Then there were no readings over 100. This week the sites at both bridge crossings in Nashua exceeded 100. SWA uses 88 as the target for acceptable bacteria levels. Anything higher than 88 can cause a small number of swimmers to get swimmer's itch, ear and eye infections, and diarrhea. That reading would cause public swimming areas to be closed down. There are no public swimming areas on either river however so these levels are only advisory.

The usual swimming holes on the Souhegan tested good this week. The Horseshoe in Wilton came in at only 40. The Boston Post Road Canoeport in Amherst tested higher than acceptable at 160 but much better than it usually tests. SWA has been looking for the causes of usually high counts at this popular swimming hole for some time but has not come up with the causes yet. Unique DNA testing of the bacteria here has been conducted for the last year to try to pinpoint the pollution source.

Generally the headwaters of the Souhegan in New Ipswich and Greenville had low bacteria counts. Good readings continued right through Downtown Wilton, which usually has high counts that go along with the increased population along the river. The site behind the mills in Wilton tested at only 92, a very low number for this site. The bacteria counts then increased as the river passed into and through Milford. One of he highest readings on the river was noted in the pond between the two dams at the Swing Bridge near the Milford Oval. The reading here was 230, still not an excessively high number. The river then recovered gradually until Rte 122 where it popped up to 230 again and then increased to 240 when measured just below where Beaver Brook joins the river in Amherst. This site had the highest reading on the entire river. The Indian Ledges area in Merrimack was not tested this week due to the monitor's being away on vacation. This site had a very high reading two weeks ago. The count then exceeded the ability of the test to accurately measure the colonies and was recorded as 'in excess of 800.' The Turkey Hill Bridge area in Merrimack, another popular swimming spot, was also not measured this week; however, this site usually tests at a very acceptable level.

This is the ninth summer that SWA has been conducting these tests on the two rivers so there is a lot of data for both rivers under various conditions. What the program has documented is that the Merrimack River has cleaned up substantially since the passage of the Clean Water Act and the improvements in the sewage treatment plants back in the 1970s. It is only under heavy rainstorm conditions that the river still reverts to being the active sewer it once was. When huge amounts of storm water go into the single sewer pipe systems in Manchester and Nashua streets, the waste treatment plants cannot handle both the sewage and the rain water. Twenty-six pipes in Manchester and nine in Nashua then release the overflow directly into the rivers. Untreated raw sewage mixed with the rainwater flows directly into the rivers and the bacteria levels shoot to astronomical levels. Both cities are under EPA direction to modify their systems so these overflows cannot occur.

The Souhegan River has no such 'combined sewer overflows' and so never sees the astronomical numbers that can be found on the Merrimack under stressful conditions. The Souhegan, however, is a smaller, less forgiving river and so usually has higher bacteria readings throughout than the Merrimack. It takes less pollution to show up more quickly on the Souhegan.

Testing on Purgatory Brook in Lyndeborough/Mont Vernon came in at only 2 colonies of bacteria per100 milliliters of water. This is the first year that regular testing is being done on this important Souhegan tributary. Readings on the various tributaries are tested on an occasional basis. Regular testing on Stoney Brook in Wilton, the largest Souhegan tributary, was stopped several years ago after not finding any unusual sources of bacteria. Purgatory Brook looks to be headed in that same direction according to Ken Butenhof, coordinator of the testing program.

Trained volunteers do all of the testing; the bacteria samples are tested at the Milford, Merrimack, and the Nashua Wastewater Treatment Facilities. The Nashua National Fish Hatchery provides the lab for testing for dissolved oxygen, which is necessary for fish and plant life. The labs at the NH Department of Environmental Services in Concord do phosphorus testing.

June 28th Description
NO PROBLEM WITH BACTERIA ON LOCAL RIVERS

Tests performed by the Souhegan Watershed Association on Tuesday morning showed generally acceptable limits for E. coli bacteria in the Souhegan River and excellent results on the Merrimack River between Manchester and Tyngsborough.

It was hazy, hot, and humid at 8 am on Tuesday morning for this week's tests on the two rivers, but there hadn't been any serious rainstorms to wash E. coli into the rivers for several days prior to the tests. Flow on both rivers has moderated since the high water levels at the first test two weeks ago. Flow on the Souhegan this week was 106 cubic feet per second. The average historic flow for this date is 91 cfs. Flow on the Merrimack was 3780 cfs. The historic average for this date on the Merrimack is 2350 cfs. Both rivers are returning to their average flows and temperatures from the high water flows and cold temperatures earlier in the season. And as this is happening the rivers are returning to more average readings for E. coli bacteria. Water temperatures averaged 77 degrees Fahrenheit.

The Merrimack River tested good throughout the stretch from Manchester to Tyngsborough. The highest bacteria level found was in the pond above the Amoskeag Dam in Manchester. That count was 60, well below the 88 target level. At Goffs Falls in Litchfield the count was only 10. The monitor at Goffs Falls, however, noted that a number of saplings had been cut and tossed into the river, an illegal activity. Landowners are not allowed to toss their leaves and brush, or anything else, into a river to dispose of it. Although the Merrimack was good throughout, only half of the twelve sites along the Merrimack were monitored this time. The program still has room for volunteers willing to spend about an hour every two weeks to monitor a site. Anyone interested can contact Ken Butenhof, coordinator of the program, at kbutenhof at comcast.net or George May, SWA president, at georgemay at adelphia.net.

The Souhegan had slightly higher than acceptable bacteria counts at many of the sites monitored. But with the exception of one site, Indian Ledges in Merrimack, the counts were reasonable. The usual swimming holes had the usual readings for this time of year. The Horseshoe in Wilton had a very low count of 35 colonies per 100 milliliters of water and Turkey Hill Bridge in Merrimack had a count of 30. Both of these counts are well below the target reading of 88 that the state uses to monitor public swimming beaches. Both of these popular swimming areas usually have acceptable readings. The Amherst Canoeport on Boston Post Road, the most popular swimming hole on the river, had a reading of 240. This is high enough to possibly cause gastrointestinal problems and ear and eye infections in some of the swimmers. This site usually has unacceptable levels.

This week also marked the first test of the season to determine the DNA of the bacteria in the Souhegan River near the Amherst Canoeport at Boston Post Road. Fourteen sites immediately upstream of Boston Post Road were sampled. All of the samples were processed at the Merrimack Wastewater Treatment Plant and the DNA testing is being done at UMass Boston. This is the second year for this highly specialized testing and is being funded by a grant from ENSR International. For years SWA volunteers have been trying without success to find the source of the high bacteria counts usually found at this popular swimming hole. It's expected that the DNA testing will eventually help identify the sources.

Trained volunteers do all of the testing; the bacteria samples are tested at the Milford, Merrimack, and the Nashua Wastewater Treatment Facilities. The Nashua National Fish Hatchery provides the lab for testing for dissolved oxygen, which is necessary for fish and plant life. The labs at the NH Department of Environmental Services in Concord do phosphorus testing.

June 14th Description
TESTING ON SOUHEGAN AND MERRIMACK RIVERS BEGINS THE 2005 SEASON

The Souhegan Watershed Association (SWA) and the Merrimack River Local Advisory Committee (LMRLAC) have begun their biweekly water quality testing program again this summer. This is the ninth summer that SWA and LMRLAC have been collecting data on water quality on these rivers. Nineteen sites along the entire length of the Souhegan are being monitored. Twelve sites along the Merrimack between Manchester and Tyngsboro are being monitored. This year testing on Purgatory Brook, an important tributary of the Souhegan, is also being added.

Tuesday morning provided a perfect time to begin the testing. Rainy weather, high water, and high temperatures all provided a time of high stress for the rivers. And that's what the testers found. Water flow on the Souhegan was almost double its historic average for this date; flow on the Merrimack was triple its historic average. The water temperature on both rivers was very close to the air temperature. This showed a very rapid increase in water temperature in a very short time, probably around 10 degrees Fahrenheit within a week. And the rain had the effect of washing pollution into the rivers from adjoining lands, roads, parking lots and storm drains. All of these factors conspired to raise the bacteria levels to marginally unhealthy levels at most of the sites tested. One site on each of the rivers reported bacteria levels higher than 1000, considerably higher than the 88 count that is used for safe swimming and bathing at public swimming areas. There are no public swimming areas on either of these rivers, but lots of private swimming takes place on both rivers. Monitors noted lots of kids swimming while the tests were being done on Tuesday morning at the Boston Post Road Canoeport near Souhegan High School in Amherst. The bacteria level there was 120, ironically one of the lowest readings for any of the sites tested, but still somewhat higher than the strictly safe level. This popular swimming hole usually has unacceptably high levels all summer long. It is also the site that is being examined for cutting-edge DNA testing of the bacteria to try to determine exactly where the bacteria are coming from. This site has been scrutinized carefully for several years without turning up the bacteria source so far.

The two sites reporting bacteria levels higher than 1000 were downstream of the Milford Wastewater Treatment Plant on the Souhegan and at the Greeley Park Boat Ramp on the Merrimack. Downstream of both of these sites the levels dropped to levels less than 1000.

Because of a first-day mixup samples taken in New Ipswich and Greenville on the Souhegan never got tested. Several of the sites that are listed to be tested also do not have monitors to do the sampling at this time. The program welcomes anyone that would be wiling to help out by adopting a site. Ones listed as NA (not available) may need a volunteer. Testing takes about an hour every other Tuesday morning between 5 and 8 am. Volunteers collect river water which is tested for temperature, E. Coli bacteria, phosphorus, dissolved oxygen, and turbidity. They also note activities and concerns at their site. Training is provided. Volunteers can get more information by emailing coordinator Ken Butenhof at kbutenhof (at) comcast (dot) net or SWA president George May at georgemay (at) adelphia (dot) net.

Trained volunteers do all of the testing; the bacteria samples are tested at the Milford, Merrimack, and the Nashua Wastewater Treatment Facilities. The Nashua National Fish Hatchery provides the lab for testing for dissolved oxygen, which is necessary for fish and plant life. The labs at the NH Department of Environmental Services in Concord do phosphorus testing. Ken Butenhof, a PhD in chemistry, coordinates the program.

The next test will be done the morning of June 28th.

Web pages by Richard Hart.
Send comments and contributions to me at harts@ultranet.com.
Or visit my family's web page.

Last modifed: