Souhegan Watershed Association

Water Testing Results
Summer 2001

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, disolved oxygen, temperature, and bacteria. Weather and streamflow information was also recorded when water samples are collected. Previous results for 1997, 1998, 1999, and 2000 results are available in a report that can be found in local libraries. Summaries are available here.

This monitoring program is conducted by trained volunteers who believe in cleaner rivers. Financial support for the program comes from a grant from NHDES and local conservation commissions. If you would like to help continue this monitoring effort, please contact George May at 883-3409 or georgemay@msn.com.

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. The current dissolved oxygen results this year are available here.

Tests for E. Coli bacteria in the Souhegan and Merrimack Rivers showed about the same results as have existed for the last month according to George May and Ken Butenhof, coordinators for the water quality testing program of the Souhegan Watershed Association and Merrimack River Local Advisory Committee.

A number of the 29 sites tested along the Souhegan River were slightly above the 88 colonies per 100 ml of water that SWA uses as a conservative standard. Public swimming beaches must test lower than 88 according to public health standards. Of the usual swimming spots along the Souhegan, the Boston Post Road Canoeport in Amherst, a popular swimming hole near Souhegan High School, was very high at 510 and the Horseshoe in Wilton was 170. Indian Ledges and Weston Park at Turkey Hill Bridge, both in Merrimack, tested very low at less-than-1 and 6 respectively. With the exception of the Horseshoe, all of these results were in line with tests done all summer long. Boston Post Road seldom has had an acceptable reading. The sites in Merrimack have usually tested very low. The Horseshoe has usually tested OK but has gone over the acceptable standard in the last month as the flow in the river has decreased.

"Most of the surprises this week were positive ones," said Butenhof. "All of the upstream sites on the Souhegan had very good results. Downtown Wilton tested at 2, a suprisingly low level; and below Pine Valley Mill in West Milford was 80. A month ago both of these sites had bacteria levels too high too count." Butenhof attributed the unexpected low readings to the rainstorm that came through on Saturday morning and flushed the river, which was very low. Also water is normally diverted from a dam through a large pipe to Pine Valley Mill, but the low flow and drawdown at the upstream dam prevented any water coming through the pipe. "That pipe is probably a source of bacteria," said Butenhof.

The biggest concern for the Souhegan is the low flow according to May. "There are places where there is no visible water at all in the riverbed." The flow on Tuesday morning when the tests were taken was 26 cubic feet per second; the normal flow for this date should be 78 CFS, three times higher. This is the second year in a row that the Souhegan has seen abnormally low flows. "I hope all the salmon that we've put into the river in the last couple of years have found a good spot to hang out," said May. The Souhegan River is the most productive river in southern New Hampshire for stocking with salmon fry to reintroduce salmon to the Merrimack Watershed. US Fish & Wildlife puts thousands of salmon fry into the river each year and schools that are part of the Adopt A Salmon Family, raising salmon in their classrooms, put all of their fish into the Souhegan. The salmon fry normally stay in the river for two years before migrating out to the ocean.

The Merrimack River again continued to have very low bacteria counts between Manchester and Tyngsboro. Most of the sites on the Merrimack had bacteria levels too low to accurately count. The Merrimack was one of the ten dirtiest rivers in the nation twenty-five years ago, before passage of the Clean Water Act required building wastewater treatment plants. For the last several years the tests have shown the river has cleaned up tremendously. The Merrimack today is considered swimmable and fishable.

The monitoring program recently secured a small grant from NH DES to measure phosphorus levels and levels of mercury and cadmium in both rivers and will be conducting these tests through the date of the last scheduled test on September 18. Volunteers will also be taking additional E. Coli tests upstream of the Sagamore Bridge to find pollution coming into that area.

Volunteers with the Souhegan Watershed Association and the Merrimack Local Advisory Committee do all of the testing. Volunteers at the Nashua Wastewater Treatment Plant, the Milford Wastewater Treatment Plant, and the Merrimack Wastewater Treatment Plant do the E. Coli testing. Volunteers at the Nashua National Fish Hatchery do testing for dissolved oxygen. All of these results along with past test results are posted on the SWA website at www.ultranet.com/~harts/swa.

August 21st results
HIGH BACTERIA COUNTS ALONG SOUHEGAN; LOW COUNTS ALONG MERRIMACK

E. Coli counts along the length of the Souhegan River were slightly higher than a month ago and similar to testing done two weeks ago according to coordinators of the monitoring program for the Souhegan Watershed Association and Merrimack River Local Advisory Committee. This test was performed on Tuesday, August 21 and is the sixth test that's been done this season.

Except for sites along the Souhegan River in Merrimack every monitoring site reported higher than acceptable E. Coli bacteria counts for public swimming areas. The two sites tested in Merrimack, both areas where swimming occurs, tested at 12 and less than 1. The acceptable level for the tests is 88 or less.

However, further upstream the Horseshoe in Wilton, a popular swimming hole, was 160. The Boston Post Road Canoeport in Amherst, another popular swimming hole, was not tested this time, but this site usually tests higher than acceptable. The last test here, on August 7, was 400.

Two Souhegan sites had readings higher than the tests can measure. Both measured greater than 800. One site was in downtown Wilton; the second just downstream of the Greenville Wastewater Treatment Plant. Downtown Wilton was expected to test high because of the intense population along the river here. The site downstream of the WWTP has had much lower counts in the other five tests taken this year. The WWTP is being coordinated by the state this year after it was found to be dumping raw sewage into the river last year.

The flow in the Souhegan continued to drop and is less than 50% of what it should be at this date. The low flow and warm temperatures are probably the cause of the higher than acceptable bacteria counts.

The Merrimack River continues to have very low bacteria levels between Manchester and Tyngsboro. For the last several years the tests have shown how much the river has cleaned up. Twenty-five years ago the Merrimack was one of the ten dirtiest rivers in the nation. Today this section is considered swimmable and fishable.

One troubling site continues to be at the Sagamore Bridge. The bacteria count here was greater than 800, higher than the test can measure. All of the upstream sites were quite low so there is something increasing the pollution at this site. Earlier in the year a blocked sewer line let raw sewage get into Salmon Brook, which flows into the Merrimack above the Sagamore Bridge. Higher counts at the Sagamore Bridge were attributed to this spill during June and July, but the spill has been cleaned up since then and should not be affecting the Merrimack now. The Nashua Wastewater Treatment Plant is also located in this area, but their discharge into the Merrimack is monitored and is usually better than the river itself. The Local Advisory Committee will be doing additional testing in this area to try to find the source of the pollution.

Volunteers with the Souhegan Watershed Association and the Merrimack River Local Advisory Committee do all of the testing. Volunteers at the Nashua Wastewater Treatment Plant, the Milford Wastewater Treatment Plant, and the Merrimack Wastewater Treatment Plant do the E. Coli testing. Volunteers at the Nashua National Fish Hatchery do testing for dissolved oxygen. All of these results along with past test results are posted on the SWA website at www.ultranet.com/~harts/swa.

August 7th results
LOW FLOW AND HIGH BACTERIA COUNTS ON THE SOUHEGAN

Heat, low flows, and dams drained for maintenance all contributed to higher than usual bacteria counts on the Souhegan and Merrimack Rivers according to the Souhegan Watershed Association and Merrimack River Local Advisory Committee, coordinators of the monitoring program.

Almost all of the nineteen sites monitored last Tuesday on the Souhegan River tested above the standard for public swimming areas. Only sites at the headwaters of the Souhegan, at the Amherst Country Club, and sites downstream in Merrimack had acceptable E. coli readings. Three sites had E. coli readings higher than the tests could measure: at Downtown Wilton, at Pine Valley Mill, and at the American Stage Festival in Milford. All three popular swimming holes on the Souhegan had readings higher than the 88 colonies for acceptable public swimming areas. The Horseshoe in Wilton was marginally higher at 120. Weston Park at Turkey Hill in Merrimack also was maginally higher at 104. The Boston Post Road Canoeport in Amherst was very high at 400.

The Merrimack River continued to have very low E. coli readings in spite of having only half of the expected historic flow for this time of year. At least as far as bacteria goes, the Merrimack is extremely clean. A discrepancy did show up again when the count increased to 240 at the Sagamore Bridge from a reading of 96 at Taylors Falls Bridge. Testers thought that similarly increasing numbers in past tests came from an overflowing sewer line that brought bacteria in through Salmon Brook. This Tuesday's discrepancy was not significant however.

The fact that there was an oily sheen on the Merrimack from the Taylors Falls Bridge upstream to the Greeley Park boat ramp for more than a week was a concern. The local rowing club has a boathouse at Taylors Falls and reported that all of their boats have been stained by the sheen. Because of the low flow in the river, creosote from the Beazer site, upstream of Greely Park, may be getting through containment buoys into the mainstream of the river.

Greenville Mill Pond on the Souhegan has been drained for dam maintenance. The volunteer monitoring this site reported that although the banks were exposed, there was very little trash along the shore, a positive note. The water level in Downtown Wilton was also way down because of the lowering of the downstream dam.

Monitors on both rivers reported fish jumping, possibly a sign of low dissolved oxygen, a problem in hot weather. Monitors test for dissolved oxygen and those results will be posted on the SWA website at www.ultranet.com/~harts/swa/soudo01.shtml.

Volunteers with the Souhegan Watershed Association and the Merrimack Local Advisory Committee do all of the testing. Volunteers at the Nashua Wastewater Treatment Plant, the Milford Wastewater Treatment Plant, and the Merrimack Wastewater Treatment Plant do the E. Coli tests. Volunteers at the Nashua National Fish Hatchery do testing for dissolved oxygen.

July 24th results
BROKEN SEWER LINE MAY HAVE AFFECTED MERRIMACK RIVER SINCE JUNE

E. Coli testing done on Tuesday, July 24, by the Souhegan Watershed Association and the Merrimack River Local Advisory Committee showed acceptable bacteria levels on the Merrimack River at both the Taylors Falls Bridge and the Sagamore Bridge. This is the first time this season since testing began on June 12. Testers have been baffled by the mysterious increase in bacteria levels between the two sites. Now they believe that the earlier poor readings may have been due to the recently discovered blocked sewer line that was feeding raw sewage into Salmon Brook and then to the Merrimack River between the two bridges. Readings at the Sagamore Bridge increased to 370 from 46 upstream at the Taylors Falls Bridge during the previous test two weeks ago. Earlier tests also showed unexplainable increases.

Bacteria levels below 88 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, while the bacteria are alive, but they do indicate the general health of the river water or problems at that moment. They also show a historic trend toward healthy or unhealthy sections of the river.

Now that the sewer line has been repaired and bacteria levels in Salmon Brook are decreasing, the discrepancy on the Merrimack has disappeared too. Tuesday's readings were 16 and 54 at the two sites, well within the acceptable level.

All of the other the readings on the Merrimack River were within acceptable levels for swimming and fishing with the exception of the area just upstream of the mouth of the Piscataquog River, near Exit 5.

Readings on the Souhegan River were pretty much normal for this time of year in spite of warm temperatures and low flows. Flows on both rivers are half of their historic averages for this date. Readings from the Souhegan headwaters in New Ipswich to Wilton were pretty good. The bacteria counts shoot up in downtown Wilton but clear up again before getting to Milford. The counts increase again in downtown Milford, stay high through Amherst, but clear up again by the time the water reaches Severns Bridge in Merrimack. The high density of people and paved surfaces increases the pollution in each of the downtown areas according to George May, SWA secretary.

There are several commonly used swimming holes on the Souhegan. The Amherst Canoeport on Boston Post Road, near Souhegan High School, had a count of 180, well above the acceptable number. Weston Park in Merrimack was an acceptable 72. The Horseshoe in Wilton was not tested this time. It had a higher than acceptable level at the last test but normally tests well below the acceptable level.

Volunteers with the Souhegan Watershed Association and the Merrimack Local Advisory Committee do all of the testing. Volunteers at the Nashua Wastewater Treatment Plant, the Milford Wastewater Treatment Plant, and the Merrimack Wastewater Treatment Plant do the E. Coli tests. Volunteers at the Nashua National Fish Hatchery do testing for dissolved oxygen.

July 10th results
HIGH BACTERIA LEVELS FOUND IN MANCHESTER

The biweekly testing of the water quality in the Merrimack and Souhegan Rivers picked up unusually high E. coli bacteria counts on the Merrimack River in Manchester. "Our past testing here has had low, very acceptable, counts," according to Ken Butenhof, coordinator of the program. "However, low flow and heavy rain were two strikes that the river couldn't handle. The flow when we tested was 1100 cfs, half of the historic flow for this date, and there was heavy local rain the previous day -- a situation that maximizes the likelihood that the city's combined sewer overflows discharged raw sewage into the river and we picked it up the next day." Test sites at Arms Park and at Goffs Falls were over 400 and just upstream of the confluence with the Piscataquog was almost 300.

The standard that the Souhegan Watershed Association and Merrimack River Local Advisory Committee, sponsors of the program, uses is 88. E. coli counts above 88 are not acceptable for public swimming beaches.

Other than that stretch, the Merrimack River once again tested at a very low level. Readings at Thorntons Ferry, Greeley Park, and the Taylors Falls Bridge were only 68, 50, and 46 respectively. A high level was reported at the Sagamore Bridge, but it dropped again before the Massachusetts border. Tests over the last several years have shown surprisingly low bacteria levels in the Merrimack between Manchester and Tyngsboro.

The Souhegan River also had lower than normal flow when the tests were taken on July 10. The flow was 90 cfs versus an historic average of 120 cfs. The headwater sites all tested positively, the sections through Milford and Amherst had unacceptable levels, and then the river cleaned up again by the time it got to Merrimack. There were a couple of surprises however. The Horseshoe in Wilton, which normally has very low counts, jumped to 190, the first time it's ever been this high; and the Boston Post Road Canoeport in Amherst, which normally has very high counts, dropped to 80. Those areas are the most popular swimming holes on the river.

Several of the monitors on the Souhegan noted foamy suds on the river in the upstream reaches. Several noted fish jumping on both rivers. And one monitor noted horse manure on the river bank. Protecting the land along the river's edge is one of the goals of the Souhegan Watershed Association and not having manure where it can be washed into the river is important, according to George May, SWA secretary. "People could help protect the river in a number of ways: picking up pet waste in yards and trails where it could be washed into rivers, brooks, or storm drains; maintaining septic systems with an inspection and pumping every 2-3 years; not feeding ducks, geese and pigeons; and maintaining a vegetative buffer between lawns and river."

June 26th results
BACTERIA NOT THE ONLY POLLUTION IN LOCAL RIVERS

The biweekly testing of the Merrimack and Souhegan Rivers indicated more than the usual kind of pollution this week. The monitor testing at the boat ramp at Greeley Park in Nashua discovered a partially submerged car in the river early Tuesday morning. However, there was good news too -- the E. coli bacteria count for that site was 58, well below the 88 standard for public swimming beaches. The abandoned car was reported to police and was towed away later in the day.

"Volunteers doing the testing always report unusual activity at their sites, but it usually involves seeing ducks or fishermen, not cars in the water," said George May, secretary of the Souhegan Watershed Association, one of the sponsors for the testing program.

E. coli counts on the Merrimack have increased slightly since the last test two weeks ago according to Ken Butenhof, coordinator for the program. "Decreased flow and increased water temperatures are both factors that facilitate the growth of E.coli," he explained. "The flow was 2900 cubic feet per second, about half that of two weeks ago, and the river temperature was about three degrees warmer. But still bacteria counts stayed low, generally within the limits for public swimming and fishing." Goffs Falls, near the railroad bridge in Litchfield, had a count of less than 1, which would meet the standard for drinking water. However, Butenhof cautions that a low count in a single sample are not sufficient to make such a determination. "The historical E. coli counts for the Goffs Falls site, which is below the Manchester Wastewater Treatment Plant, are below 10 which is considered safe for swimming and fishing."

Readings on the Souhegan went up and down. The headwaters above Water Loom Pond in New Ipswich were 36. But they increased to 335 at Highbridge, went down again above Greenville Mill Pond, and up again just below the town of Greenville. Of interest are the low readings seen just downstream of the Greenville Wastewater Treatment Plant. This plant has had illegal discharges in the last couple of years and is now under state supervision to clean it up.

At the last test the Amherst Canoeport near Souhegan High School had a reading of 0 but was suspected of being incorrect. This week the reading was 360, a reading more usual for that particular site. This site has been a popular local swimming hole but typically has had readings in excess of those required for healthy swimming. Readings at the Horseshoe in Wilton and at Weston Park in Merrimack, other popular swimming spots, were well within limits.

All of the testing is done by volunteers with the Souhegan Watershed Association and the Merrimack Local advisory Committee. The E. coli tests are done by volunteers at the Nashua Wastewater Treatment Plant, the Milford Wastewater Treatment Plant, and the Merrimack Wastewater Treatment Plant. Testing for dissolved oxygen is done by volunteers at the Nashua National Fish Hatchery. Some of the sites could still use a volunteer and interested citizens can contact coordinator Ken Butenhof at (603) 644-3431 or pennanti@mediaone.net.

June 12th results
WATER TESTING FOR SOUHEGAN AND MERRIMACK RIVERS BEGINS NEW SEASON

The Souhegan Watershed Association (SWA) and the Merrimack River Local Advisory Committee (LMRLAC) have begun their biweekly water quality testing again this summer. This is the fourth summer SWA and LMRLAC have been collecting data on water quality on local rivers. Nineteen sites on the Souhegan are being monitored. Twelve sites on the Merrimack between Manchester and Tyngsboro are monitored.

One of the tests being done is for E. Coli bacteria. Bacteria levels below 88 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, while the bacteria are alive, but they do indicate the general health of the river water or problems at that moment. They also show a historic trend toward healthy or unhealthy sections of the river. SWA and LMRLAC will release the bacteria counts as soon as they are available, generally two days after the actual testing. The bacteria counts for each site all season long as well as past years' results will also be available on the SWA website, www.ultranet.com/~harts/swa. Printed copies of the reports from past years showing all of the tests performed are also available at local libraries and conservation commissions.

This year three new sites on the Souhegan have been added, one to monitor downtown Wilton, another to provide data where a golf course is being considered at Hayward Farms in Milford, and the third between the Ponemah Green and Amherst Country Club golf courses where high phosphorus counts have been seen. Three new sites have been added on the Merrimack River also to include Manchester above the Amoskeag Dam.

Heavy rains the night before the testing seem to have modified the E. Coli counts. There are high counts in the Souhegan and low counts on the Merrimack, at least above the CSOs below the Nashua River. CSOs are Combined Sewer Overflows that allow untreated raw sewage to flow directly into the Nashua and Merrimack Rivers during heavy rainstorms. Normally water that goes into street storm drains goes to the sewage treatment plant, but during heavy rains the treatment plants can't handle the increased flow. Manchester has a total of 26 CSOs on the Piscataquog and Merrimack Rivers. Nashua has 9.

Heavy rains the night before the testing seem to have modified the E. Coli counts. There are high counts in the Souhegan and low counts on the Merrimack, at least above the CSOs below the Nashua River. CSOs are Combined Sewer Overflows that allow untreated raw sewage to flow directly into the Nashua and Merrimack Rivers during heavy rainstorms. Normally water that goes into street storm drains goes to the sewage treatment plant, but during heavy rains the treatment plants can't handle the increased flow. Manchester has a total of 26 CSOs on the Piscataquog and Merrimack Rivers. Nashua has 9.

The Souhegan is a more flashy river, however. High E. Coli counts were seen through the entire length of the river, probably attributable to bacteria being washed into the river from the rains the night before and the low flow in the river. The flow was below its historic average in spite of recent rains. Flow on Souhegan was 150 CFS and historic flow for that date is 200.

One of the Souhegan sites showed 0, which is perfect. The Amherst Canoeport on Boston Post Road, near Souhegan High School, has tested very high in the past, however, so this low count appears suspect. The new site in downtown Wilton had a very high bacteria level, above 800, too high to count. The new site behind the Hayward fields in Milford had a very acceptable level of 90, lower than all of the surrounding sites tested. The new site at Amherst Country Club was very high, but similar to surrounding sites.

"Generally, there are no immediate problems on either river that need to be addressed at this time. Nothing unusual showed up on this date," according to George May, secretary of the Souhegan Watershed Association.

Testing is done every two weeks by trained volunteers and is partly funded by local conservation commissions and volunteer fundraising. There is still a need for volunteers to help with testing this summer. Coordinator Ken Butenhof can give prospective volunteers more information at (603) 644-3431. The next test will be on June 26.

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Last modifed: 9/22/01

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