Executive Summary
River Watch 2008

Hanson Middle School
Anita Kofton

SLIDE 3: The Indian Head River forms the Northern Border of the Town of Hanson, Other towns that impact the water quality directly in the areas of study include Pembroke to the east and Hanover to the north, northeast. There are approximately 8 miles between our upstream site near Factory Pond and our downstream site at Ludham’s Ford or as other’s call it, Curtis’ Crossing. The river covers about eight acres of land in this area and was most likely used as a fishing and travel spot for the Wompatuck Indians.

A guide named James Luddam carried Governor Winthrop across the Indian Head River in 1632 in order to get to Weymouth, Massachusetts.

Though the river is called The Drinkwater River in other towns, we have chosen to refer to it as the Indian Head River in the scope of our study.

There is a small beaver population and the river is annually stocked with trout. Massachusetts Fish and Wildlife has posted the river in it’s entirety from Forge pond in Hanover to route 3 in Norwell and Pembroke including Factory Pond as P6; fishing resources contaminated with mercury. If herring are caught, they must be thrown back into the river. This applies more to the Pembroke side of the river, as there is a fish ladder in Luddams Ford Park. The likely source of the contamination is from the no longer existing Clapps Rubber Factory.

Two new housing developments bracket the river just downstream of our site B location (State St.), one in the town of Hanson and the other in the town of Hanover.

SLIDE 4: This year we sampled at three sites along the river:

Ø Site A: Broadway Street in Hanson is our up stream site

Ø Site B: State Street in Hanson is approximately midway between site A and site C

Ø Site C: Curtis Crossing. The river here defines the line between the towns of Hanover and Pembroke

SLIDE 5: The road map shows the course the river takes after our furthest downstream site. From this point onwards, the river is known as the North River. The North River empties into Scituate Harbor.

SLIDE 6: This is our Site A at Broadway Street. Just upstream is an impoundment that releases water from Factory Pond into the river. The bottom is generally cobbled but there are sandy spots all along the edges and under the vegetation.

SLIDE 7: Here are the 17 hour dissolved oxygen and temperature data for October.

Typically, as temperature decreases, DO increases which we see in the first hours of data collection.

SLIDE 8: These are the 17 hour dissolved oxygen and pH results from October. It shows a nice relationship between pH and DO. When dissolved oxygen concentrations are high, the pH of the water is higher showing that photosynthesis is taking place. However, as the night time hours persist, dissolved oxygen concentrations decrease as do pH levels showing a rise in carbon dioxide levels (acidification)

SLIDE 9: This is our Site B site at State St.

The water flows from a small impoundment upstream and splits into two parts creating a small island. The two streams reunite about 500 yards from the split. This is where we took our samples. The flow is swift as the two streams unite.

There is also a bridge that spans the river just down stream of the impoundment.

SLIDE 10: Here are the dissolved oxygen levels and temperature comparisons for site B. Despite the strong current and mixing as the two streams come together, dissolved oxygen levels are slightly lower that those at Site A and there are no wide fluctuations in temperature as we saw at site A.

SLIDE 11: This is the comparison of pH and Dissolved Oxygen for site B. The pH is higher here than at site A. This could be a result of the bridge construction and crumbling of the cement portions of the bridge.

SLIDE 12: This is our third site at Curtis Crossing in Pembroke. The habitat is pretty much like that at Site A, rocky cobble and riffle but sandy along the edges and under the vegetation. One thing we thought was strange was that the discharge here seemed to be much lower that it should be considering what it has been in past years and the distance down stream from site A. Once again, there is an impoundment directly upstream of this site and another cement bridge that spans the river.

SLIDE 13: Dissolved oxygen is slightly higher here than at Site B.

SLIDE 14: pH is lower here than at Site B. This graph also shows a good relationship between Dissolved oxygen and pH. (pH is high during daylight hours when photosynthesis takes place, but the water becomes more acidic as less carbon dioxide is absorbed during the night time hours.).

SLIDE 15: This graph compares Dissolved Oxygen for all three sites. The lowest levels are at Site B. The average DO for site A is 7.90 mg/L, for Site B is 7.63 and for site C is 8.35. These readings are above the acceptable limits in Massachusetts waterways for both warm water and cold water fisheries.

SLIDE 16: This graph shows the comparison of pH for the three sites: The average pH at Site A is 7.0, For Site B is 8.30 and for Site C is 7.0.

SLIDE 17: Finally, we compared the Temperature data for the three sites. The average Temperature for Site A was 15.53 oC, for site B was 14.33 oC and for Site C was 15.12412 oC.

SLIDE 18: This graph shows all of the average data including the average oxygen saturation for each site. As you can see, both sites A and C compare pretty well, however in each measurement taken, it looks like Site B is slightly off with a lower temperature, a higher pH and lower oxygen saturation that the other two sites.

SLIDE 19: This is the nitrogen load data (kg/day) for the three sites. The one interesting thing that we found was that the load is much lower that it has been in other years.

SLIDE 20: Here, we have included data collected since our monitoring began 2001. The highest loads were reported in the fall of 2003 and then again in the fall of 2004. This year the load in all three sites is relatively low. What the root cause of high concen--trations of nitrogen still remains a mystery.

SLIDE 20: Here we are trying to show the net change in the upstream discharge at Site A (Broadway St.) to downstream discharge at site C (Curtis Crossing). We thought that there might be a relationship between the reductions in load this year to the discharge of the river beginning at Site A. The difference in discharge in 2001 was almost 16 cubic feet per second. Last October, the difference in discharge between the two sites was a little over 2 cubic feet per second. Where did the water go?

SLIDE 21: There is a stream gauge at Site C in Pembroke and these are the mean discharge measurements for the past 19 years. The low readings in 2003 helped us to confirm the accuracy of past measurements. The data also helps to illustrate the wide fluctuations in discharge over a long period of time.

SLIDE 22: Macroinvertebrates and the Biotic Index:

Multiple sweeps were made in each of the habitat types at all three sites. We combined all of our sweeps. Later, picks were taken from each sample using the density adjustment factor to two hundred organisms.

SLIDE 23: Results for Site A:

Ø About 47% of the sample was made up of net-spinning members of Trichoptera. Approximately 1% of the sample was cased Caddisfly larvae.

Ø 12 percent of the sample were amphipods or scuds

Ø 35 percent were fingernail clams and snails.

There was a fair representation of organisms from many different families including dragonfly larvae, beetle larvae and midges. We did not find any representative mayflies or stoneflies at this site.

The biotic index or measurement of the relative tolerance and biodiversity of the sample was pretty good at 4.538.

SLIDE 24: Results for Site B:

Ø 50 percent of the sample was made of the net-spinning caddisfly, Hydropsychidae.

Ø 18% of the sample consisted of the other net-spinner, Philopotamidae.

Ø Approximately 20% of the sample from Ephemeroptera (Heptagendae)

The biotic index or 3.9 was also pretty good

SLIDE 25: Hydropsychidae is also the dominant organism at site C. There is a little more biodiversity here and more representatives with a lower biotic index give this site the best biotic index 3.68) of the three sites studied.

SLIDE 26: We collected water samples in early April and analyzed them for Fecal Coliform concentrations here at the watershed lab. The average for all three sites was below 35 colonies per 100 ml. This tells us that the nitrogen load is probably not due to any significant septic contamination.

SLIDE 27: CONCLUSION: In conclusion, we found the Indian Head River at our three study sites to be relatively healthy. The biodiversity at all three sites is good and the nitrogen load is way below what it has been in past years.

Even though it was a strain to do three sites, it was interesting to have the middle site at State street this year. This showed us that there can be minor, unexplainable differences along the course of a river. Could it be the bridge that is raising the pH at Site B? Is it some other factor that not only affects pH but also the temperature and the dissolved oxygen? There are such similarities between Broadway St. and Curtis Crossing that it seems significant even though the differences at State St. are small.

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Please see the PowerPoint Presentation for details.