Souhegan Watershed Association

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2002 E-coli results
2001 Testing Results Summary
2001 Desolved Oxygen results
2001 E-coli results
2000 Testing Results Summary
2000 Souhegan E-coli results
1999 Testing Results Summary
1999 Souhegan E-coli results
1998 Testing Results Summary
1998 Souhegan E-coli results
1997 Souhegan E-coli results
Stream Flow Measurements

Water Testing Results
Summer 2002

Souhegan and Merrimack Rivers

George May's Latest Results Summary

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 not yet available.


September 17nd results
RAIN BROUGHT UP E. COLI LEVELS BUT NOT RIVER LEVELS

The first substantial rain in quite a while seems to have washed pollution into the Souhegan and Merrimack Rivers. For the first time this year the water quality monitoring project of the Souhegan Watershed Association and the Merrimack River Local Advisory Committee recorded high levels of E. coli at a number of sites in both rivers according to Ken Butenhof and George May, coordinators of the project.

The rain, however, didn't do much to relieve the very low, drought condition flows on both rivers. The Merrimack River between Manchester and Tyngsborough had a flow of only 450 cubic feet per second at the time of the test. This is less than one third of the average flow for the last 65 years for this date. The average for this date is 1500 cfs. "Of even more concern is the fact that the flow is substantially below the 7Q10 flow that hydrologists us to determine the absolute minimum flow," said May. The 7Q10 required flow is 650 cfs. This stretch of the Merrimack has been below its 7Q10 level since September 11.

The Souhegan River fared a bit better. The flow was 24 cfs, above the 7Q10 level of 13 cfs for this date, but still well below the average of 46 cfs. People driving along the river have noted several places where they could walk across the river without getting their feet wet.

People driving over the Merrimack bridges may see lots of water below, but that is all ponded up by the dam in Lowell. There is very little water coming in.

The water test on September 17 was the last of the eight tests done by the two river groups this season. It was also the first test done this year after a moderate rainfall. Most rainstorms, ironically, cause an increase in bacteria. Pollution stored up on the river banks gets washed into the rivers, especially near population centers where roads, parking lots, and storm drains flush directly into the river. And that happened in Milford where bacteria levels soared. The acceptable level for E. coli bacteria colonies used by the testers is 88. This is the level required by the state for public swimming areas. The reading at the Swing Bridge, just downstream of the Milford Oval, was 760. The reading taken near Pine Valley Mill, where Rte 101 branches into Wilton, was greater than 800, higher than the test could accurately measure. The Souhegan didn't clean up until all the way through Amherst to Merrimack.

The center of Wilton, however, had a relatively low reading of 96, still higher than the 88 desired. But that level in a downtown, heavily paved, heavily populated, area is good. Downtown Wilton has had a number of desirable readings this summer, causing the SWA and the Wilton Conservation Commission to survey the area to see if the intermittent pollution coming in can be cleaned up.

The Souhegan headwaters in New Ipswich and Greenville again had acceptable E. coli levels with one exception. The site just below the Greenville Wastewater Treatment Facility had a reading of 360. This facility is being monitored by the state because of violations in the past.

The testing program is an all volunteer project of the two river groups. Trained volunteers monitor each of the 31 sites and test for temperature, dissolved oxygen, turbidity, and phosphorus besides E. Coli bacteria. Volunteers at the Nashua, Merrimack, and Milford Wastewater Treatment Facilities do bacteria testing. Titration for dissolved oxygen is done by the Nashua National Fish Hatchery and NH DES in Concord does phosphorus testing.

Past results and additional information is available on the SWA website at www.ultranet.com/~harts/swa. Printed reports of the full testing program from past years are available from the conservation commissions and libraries in all of the watershed towns.

September 2nd results
E. COLI LEVELS IN DOWNTOWN WILTON AND MILFORD RAISE CONCERNS

The intermittent rains before the recent water quality tests on the Merrimack and Souhegan Rivers did little to raise the E. Coli levels on either river. The Merrimack River between Manchester and Tyngsboro had only one of the twelve sites showing an unacceptable level for public swimming areas. The test site near the Sagamore Bridge had a level of 140 colonies of bacteria per 100 milliliters of water. The acceptable level is 88. "This is higher than our last test two weeks ago when every site was acceptable, but it's still very good," according to George May, one of the coordinators for the program sponsored by the Souhegan Watershed Association and the Merrimack River Local Advisory Committee. "Our real concern for the river right now is for the amount of water in the river rather than the bacteria level," he said. The flow on the Merrimack on Tuesday, the day of the test, was 700 cubic feet per second. The historical average for this date is double that, 1400 cfs. The 7Q10 level, which is the level that hydrologists use to determine absolute minimum flow, is 640 cfs. This is slightly better than two weeks ago but still very close to the minimum flow.

Flow on the Souhegan River fared slightly better than on the Merrimack, but not by much. The Souhegan's flow was 26 cfs, but it should be 36 cfs to meet the historical average measured over the last 65 years. The minimum 7Q10 flow on the Souhegan for this date is 15 cfs. Minimum flows on the Souhegan River are the subject of a pilot study being done over the next couple of years by the NH Department of Environmental Services as a model for all New Hampshire rivers. Both rivers spiked up in flow after the heavy rain on Thursday and Friday but came right back down quickly.

The E. Coli levels on the Souhegan were low through the headwaters in New Ipswich, Greenville, and as far downstream as Downtown Wilton. This includes the Horseshoe, a popular swimming hole in Wilton, where readings were 48, well below the 88 level used by the program. The swimming hole at the Boston Post Road Conoeport in Amherst did not fare so well. The level there was an unacceptable 200.

Readings in the downtown areas of Wilton and Milford were very high and seemed to indicate pollution coming from specific sources according to May. The level in Downtown Wilton was 410. This site has had some very high readings and some very low readings during the seven tests done so far this season. This inconsistency means that pollution is not present all the time and the SWA and the Wilton Conservation Commission will be investigating this area for pollution sources.

The level near the American Stage Festival just upstream of the Milford Oval had a very high reading of 846. This site is across from Keyes Field and indicates a possible problem here. Last year there was an incident where a portable toilet was overturned and pollution got into the river. The information has been reported to the town to investigate.

An E. Coli reading higher than 88 means that a small percentage of swimmers could experience ear or eye infections and intestinal distress. The higher the level gets the greater the percentage of ailments. A reading of 88 would close public swimming areas in New Hampshire. There are no public swimming areas on either river, but this is the level that the SWA and LAC uses to determine the health of the rivers. Trained volunteers monitor each of the 31 sites and test for temperature, dissolved oxygen, turbidity, and phosphorus besides E. Coli bacteria. Volunteers at the Nashua, Merrimack, and Milford Wastewater Treatment Facilities do bacteria testing. Titration for dissolved oxygen is done by the Nashua National Fish Hatchery and NH DES in Concord does phosphorus testing.

Past results and additional information is available on the SWA website at www.ultranet.com/~harts/swa. Printed reports of the full testing program from past years are available from the conservation commissions and libraries in all of the watershed towns.

The next and final test for the season will be done on September 17.

August 20th results
LACK OF RAIN REDUCES E. COLI IN AREA’S RIVERS

The Souhegan and Merrimack Rivers have both tested relatively clear of E. Coli bacteria all season long. But the recent test by the Souhegan Watershed Association and Merrimack River Local Advisory Committee, the groups responsible for the water quality testing program, show that both rivers are even cleaner now. Coordinators for the program believe that the lack of rain is responsible for the lack of bacteria.

Testing on the Merrimack River between Manchester and Tyngsboro show that not a single site had a reading above 88, the standard that is allowed for public swimming beaches in New Hampshire. Of the nine sites tested the highest was 36. Four of the sites had no discernable bacteria. And one site had a reading of 1. “This is the first time since 1999 that we have had these low numbers on every one of the Merrimack sites,” according to George May, one of the coordinators for the program.

Several of the monitors noted how clear the water was also. This may be because there has not been a lot of water flowing to stir up sediment. There has been little flow in the river because of the drought. The flow on Tuesday morning was only 660 cfs. The historical average for this date is 1400. The 660 cfs flow is very close to the 7Q10 level that hydrologists use to determine absolute minimum flow. The 7Q10 level for this date is 650 cfs.

The Souhegan River is also approaching its 7Q10 level but not as dire as the Merrimack. Flow on the Souhegan was 20 cfs. The historical average is 42. And the 7Q10 level is 13.

Bacteria levels on the Souhegan were generally lower than during other tests this summer. All of the tests upstream of Milford were lower than 88 with one exception. That exception was at the Horseshoe in Wilton, a popular swimming hole. The reading of 124 is the first time that this site has not had acceptable bacteria levels this season. A reading of 124 is not very high, but any level higher than 88 means that a small percentage of swimmers could experience ear or eye infections and intestinal distress. The higher the level gets, the greater the percentage of ailments.

The Boston Post Road Canoeport in Amherst, another popular swimming hole, had a reading 253. This is the highest reading at this site this summer. This site almost always tests higher than acceptable, and the Town of Amherst has posted warnings about swimming here.

Spots on the Souhegan where kids swim in the town of Merrimack tested very low. Indian Ledges had a reading of 1. Turkey Hill Bridge had a reading of 0. These are slightly lower than usual readings at these sites, but both sites have had acceptable readings all summer.

This was the sixth test performed by volunteers this season. There are two more tests scheduled for September 3 and 17. Past results and additional information is available on the SWA website at www.ultranet.com/~harts/swa.

August 6th results
SOUHEGAN AND MERRIMACK RIVERS TEST CLEAN

“More of the same.” That was the verdict on the testing for E. Coli bacteria on the Souhegan and Merrimack Rivers on Tuesday, August 8. Both rivers have tested fairly clean all season long according to the Souhegan Watershed Association and Merrimack River Local Advisory Committee, the groups responsible for the water quality testing program, and this test continued the trend.

Both ends of the Souhegan and all of the Merrimack between Manchester and Tyngsboro tested well below the 88 colonies of bacteria that is required for public swimming beaches in NH. The middle stretch of the Souhegan continued to have higher than acceptable counts just as it has most of the summer. Three sites from the middle stretch tested very high. Downtown Wilton, downtown Milford, and the Amherst Canoeport on Boston Post Road had counts exceeding 200. The Canoeport is a popular swimming hole that unfortunately almost always has counts higher than acceptable for public swimming. The town has posted the area to discourage swimming there. Bacteria counts higher than 88 indicate that swimmers stand the chance of ear and eye infections and possible intestinal distress.

Having high counts in the downtown sections of Wilton and Milford are to be expected because of the high concentration of people, density of buildings, and storm drain runoff. However, Downtown Wilton has tested very clean in prior tests this summer so this test’s high numbers came as a surprise according to Ken Butenhof, coordinator of the monitoring program. Two weeks ago Downtown Wilton tested at no bacteria. This week it tested in excess of 320 colonies, higher than could be accurately counted by the test. "This may indicate an intermittent pollution problem downtown. And if that’s so, it can be cured. Upstream tests fine and always does. Maybe Wilton can have clean water downtown,” said George May, SWA secretary.

Other swimming holes on the Souhegan tested fine. The Horseshoe in Wilton and several swimming spots in Merrimack were below the 88 limit.

One additional test was done this week on Curtis and Purgatory Brooks in Lyndeborough. Curtis Brook runs into Purgatory Brook and Purgatory Brook runs into the Souhegan just upstream of the Milford Fish Hatchery. A scenic trail open to the public runs along Purgatory Brook to Purgatory Falls. There has been some discussion about forming a Purgatory Brook Watershed Association and NH DES has fined a Lyndeborough landowner for dumping human waste along Curtis Brook. Fortunately very little bacteria was found at this site. Additional testing will be done later in the season.

None of the Merrimack River sites tested above the 88 limit this week. Eight of the eleven sites tested had numbers in the single digits. The other three tested at around 40 colonies. This is similar to the pattern seen on the Merrimack all summer. “The Merrimack may have other chemicals in it. We don’t test for everything. But as far as bacteria go, it’s very clean,” according to May. “We did test for heavy metals last year and it came out clean there also,” said Butenhof.

Before the passage of the Clean Water Act thirty years ago the Merrimack was listed as one of the ten dirtiest rivers in the country. At that time one of the other rivers on the list actually caught fire. Today the Merrimack is considered swimmable and fishable.

Monitors noted that the flow in both rivers was slightly below normal for this time of the year. The Souhegan was flowing at 36 CFS and the normal flow for this date is 43 CFS. The Merrimack was flowing at 1200 CFS and the normal flow there is 1550. There was no rain in the three days prior to the test. Rains can wash bacteria into the rivers.

July 23th results
RIVER E. COLI LEVELS FIT PATTERN

The E. Coli bacteria levels on the Souhegan and Merrimack Rivers continue to follow the pattern seen for the last two months. There were a few slight changes, mostly for the better, and a couple of expected increases in Amherst, but generally both rivers look pretty good according to information provided by Ken Butenhof, coordinator of the monitoring program for the Souhegan Watershed Association and Merrimack River Local Advisory Committee, the groups responsible for the water quality testing program.

Several patterns appear in the last four tests taken every other week since the beginning of June. On the Souhegan the headwaters in New Ipswich are relatively clean and stay clean through Greenville and right through Downtown Wilton. “That’s one of the surprises this year,” said George May, SWA monitor. “We’re seeing very low bacteria counts right downtown. In past years the counts were high – what you’d expect in any downtown area. But this year they’re great. We’ve had two tests there that had numbers too low to count.” SWA/LAC uses 88 colonies per 100 mL of water as their standard. That’s the standard set for public swimming areas in NH.

From the Pine Valley Mill area in West Milford through Amherst the bacteria counts increase. All of the nine sites tested are above the 88 count standard. Especially where the river meanders back and forth through Amherst the counts almost always exceed the 88 count. Two of the sites in Amherst jumped to just about double the already unacceptable counts that they’ve shown all season. The Boston Post Road Canoeport rose to 245 from 120 two weeks ago. This is a popular swimming hole that the town has posted out of concern for health.

Again the Souhegan returns to pristine conditions as it passes through Merrimack. Both of the two sites tested in Merrimack had essentially no bacteria. Some kids swim near the Turkey Hill Bridge at Weston Park.

The Merrimack River continues to have very low bacteria counts,” said Butenhof. This test saw only one site on the river, at Depot Street in Merrimack, with a count exceeding 88. Even the area around the Sagamore Bridge in Nashua had an acceptable level this week. The count here was 40, down from 200 two weeks ago. The Merrimack River has tested very well for the last several years. This is quite an improvement from when the Clean Water Act was introduced thirty years ago. Back then the Merrimack was listed as one of the ten dirtiest rivers in the United States.

Monitors noted that the flow in both rivers was normal for this time of the year. The Souhegan was flowing at 40 CFS and the normal flow is 55 CFS. The Merrimack was flowing at 1400 CFS and the normal flow there is 1650. Many monitors reported lots of animals enjoying the river early Tuesday morning also. Geese, all kinds of songbirds, a mink, and lots of fish were noted. There was no sign of the oil sheen reported two weeks ago.

Testing is done every two weeks by trained volunteers and is partly funded by local conservation commissions and volunteers fundraising. The Milford, Merrimack, and Nashua Wastewater Treatment Facilities do bacteria testing. The titration for dissolved oxygen is done at the Nashua National Fish Hatchery. The next test will be done on August 6. Past results and additional information is available on the SWA website at www.ultranet.com/~harts/swa.

July 9th results
BACTERIA LEVELS CONTINUE UNCHANGED

The E. Coli bacteria levels on the Souhegan and Merrimack Rivers remain essentially the same as they have been since testing began this summer. “There are a couple of surprises, good and bad, that have shown up in the tests so far,” according to George May from the Souhegan Watershed Association and Merrimack River Local Advisory Committee, the groups responsible for the water quality testing program.

“The good news is that both ends of the Souhegan appear to be very clean this year. The headwaters for the Souhegan show a marked improvement over the last several years.” The Souhegan headwaters are in New Ipswich and Greenville, NH. “With one exception the river is relatively free of bacteria all the way to downtown Wilton,” May said. That one exception is in the area where the Greenville Wastewater Treatment Plant discharges to the river. Above the plant the reading was 4 colonies per 100 mL of water; below the plant the count jumped to 184. The cutoff standard that the program uses is 88. E. Coli counts above 88 are not acceptable for public swimming beaches. All wastewater treatment plants remove bacteria from their discharge before releasing it to the river. The Greenville plant has been cited in the past for illegally releasing untreated sewage directly to the river and is presently being supervised by the NH Department of Environmental Services. The operator of the plant was contacted by phone and indicated that he did not know of any reason for the higher counts below the plant and said that the plant was operating properly. Pilgrim Foods also operates a large factory in that area and has also had problems in the past.

“The other good news is not a surprise,” said May. “The Merrimack River looks very clean and that’s what we expected. Four of the sites tested at less than one colony per 100mL. At the sophistication level of the tests that we do, we could not detect any bacteria. And that’s great.” The Merrimack is tested between the Amoskeag Bridge in Manchester and the Tyngsboro Bridge in Tyngsboro, MA. Volunteers at the Nashua, Milford, and Merrimack Waste Treatment Plants perform the tests.

The bad news also concerned the Merrimack River. An oily sheen was noticed on the river all the way from Depot Street in Merrimack to the Sanders plant in Hudson. The monitors could not explain where the oil was coming from, but several monitors reported fish jumping out of the water in this same stretch of the river. Jumping fish may indicate low concentrations of dissolved oxygen, but the results of that test were not available yet. The Local Advisory Committee has been watching for intermittent oily discharges that show up on the river and that appear to be coming from the Manchester Airport. “We don’t know where this oil came from,” said May, but one of the many fishermen on the river indicated that it first showed up on the river in Merrimack at 5:30.”

Areas on the Souhegan where kids swim showed the same as usual. The Horseshoe in Wilton was within the acceptable limit at 84. Turkey Hill Bridge in Merrimack was less than one. The Amherst Canoeport at Boston Post Road was 120. The Boston Post Road site usually tests higher than the acceptable limit and the town has discouraged swimming there.

Testing is done every two weeks by trained volunteers and is partly funded by local conservation commissions and volunteers fundraising. The Milford, Merrimack, and Nashua Wastewater Treatment Plants do bacteria testing. The titration for dissolved oxygen is done at the Nashua National Fish Hatchery. The next test will be done on July 23. Past results and additional information is available on the SWA website at www.ultranet.com/~harts/swa.

June 25th results
BACTERIA LEVELS SHOW SLIGHT RISE ON LOCAL RIVERS

The E. Coli bacteria levels on the Souhegan River and on the Merrimack between Manchester and Tyngsboro showed very similar levels to the testing done two weeks ago. “There is a slight increase at most of the sites we tested this week, but considering the warmer temperatures and decrease in rainfall frequency there is little change. It’s what we expected,” said George May from the Souhegan Watershed Association and Merrimack River Local Advisory Committee. “Both rivers appear generally clean at this point,” said May.

The headwaters for the Souhegan River tested well below the acceptable level for swimming areas all the way to Downtown Wilton. The swimming hole at Horseshoe Falls in Wilton tested at 32, well below the 88 required for public swimming areas. From here to Merrimack, through Milford and Amherst, all of the sites tested above the acceptable level of 88 but only marginally so. The swimming hole at the Boston Post Road Canoeport in Amherst tested a t 150. Two weeks ago the level was only 73, one of the few times in several years that this site tested acceptably.

Bacteria levels on the Merrimack River also showed slight increases from two weeks ago. From Manchester to Thorntons Ferry in Merrimack the bacteria levels were acceptable. From Thorntons Ferry to Tyngsboro the river showed marginally high levels. The Taylors Falls Bridge site in Nashua, just below the mouth of the Nashua River, was 88, exactly the acceptable limit.

The flow on both rivers was higher than the historic average for this date. The Souhegan had 300 CFS (cubic feet per second). The historic average is 90. The Merrimack had 6000 CFS. Its historic average is 2500.

Souhegan monitors reported no visible signs of damage from the recent oil spill at Highbridge in New Ipswich. The monitoring site at Highbridge is the same place where vandals damaged a heating oil tank right alongside the river and allowed oil to get into the Souhegan last week. “We’re very pleased with this report,” said May. “We were concerned that there would be damage.” Absorbent booms were placed in the river and any floating oil was pumped out on a regular basis by a contractor for the state.

Another of the tests done by the monitors is a test for dissolved oxygen contained in the water. Low DO numbers are bad for the fish. The most recent test shows disturbingly low numbers for this early in the season. The site at the Amherst conservation land off Fairway Road across from Amherst Country Club had very low readings. “High phosphorus readings that we’ve seen here are probably promoting abnormal plant growth and robbing the oxygen from the water,” according to Ken Butenhof, coordinator of the monitoring program. “We’ll be watching this,” he said.

June 11th results
TESTING OF SOUHEGAN AND MERRIMACK RIVERS BEGINS 2002 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 fifth summer SWA and LMRLAC have been collecting data on water quality on these rivers. Nineteen sites on the entire length of 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 small 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 within the two watersheds.

Lots of continuing rain showers for the last couple of weeks seems to have washed away any bacteria along both rivers. Even sites in the center of towns along the Souhegan show low counts when compared to past results. And since there was no heavy rain immediately before the testing, the CSOs were not releasing raw sewage into the Merrimack. CSOs are Combined Sewer Overflows that allow untreated raw sewage to flow directly into the Merrimack River 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 and dumps it directly to the river. Manchester has a total of 26 CSOs flowing into the Merrimack River. Nashua has 9. There are no CSOs on the Souhegan.

The flow on both rivers was very similar to the historic averages for this date. Flow on the Souhegan was 380 CFS. The historic flow for June 11 for the last thirty years is 240. The flow on the Merrimack was 4300 CFS and the historic flow for this date is 4500. Flow on the Merrimack is controlled by the Amoskeag Dam in Manchester; there are no dams that control the flow on the Souhegan.

Swimming holes along the Souhegan all had acceptably low levels of bacteria. The Canoeport at Boston Post Road in Amherst, near Souhegan High School, tested at 73, well below the acceptable limit. This popular swimming spot typically has had high bacteria counts in the past - and probably will again when the rains stop and the weather heats up. The Horseshoe in Wilton tested at 33. This spot typically has had acceptable counts in the past.

Surprisingly the center of Wilton had bacteria too few to count. The center of Milford also had low counts, 130 above the center of town at the American Stage Festival and 60 below the center at the Swing Bridge. Typically the bacteria counts increase as the Souhegan runs through the center of towns, where the pollution from runoff of streets, parking lots and buildings occurs.

The Merrimack River between the Amoskeag Bridge in Manchester and the Tyngsboro Bridge had extremely low bacteria counts. A couple of sites had too few bacteria colonies to count. The highest level was reported at the Thorntons Ferry boat landing in Merrimack where the count was 130. The Merrimack River usually has very acceptable bacteria levels. In spite of the public's perception of the river, the Merrimack is generally quite clean.

"We're very pleased to be starting a new season and to be starting off on the right foot - all of the data shows that we're starting with two clean rivers," according to George May, SWA secretary.

Testing is done every two weeks by trained volunteers and is partly funded by local conservation commissions and volunteer fundraising. Bacteria testing is done by the Milford, Merrimack, and Nashua Wastewater Treatment Plants. The next test will be done on June 25.


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Last modifed: 1/5/03