Lee B. Hotchkiss and Beverly Stern
Part B. The Mill River Watershed
Water is collected when rain drains from higher levels to lower levels. The area drained by a stream and its tributaries is the stream’s drainage basin or watershed.
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These areas are usually natural boundaries, but in some cases man has delineated boundaries and has mapped and recorded them. We will consider the watershed of the Mill River. There is available a large map of the area given by the Southern Connecticut Regional Water Authority showing the extent of their boundary lines from the headlands in the Cheshire area and extending to the Lake Whitney Dam. The Connecticut State Geological Map (fig. 9) follows the natural boundary of the river to its mouth at the New Haven Harbor. But, since the section from the mouth to the dam is tidal and the height of the river slowed down at full tide by flood gates, the salinity and pollution would not make it useful. As it is, the Authority owns only about 3% of this large watershed, consisting of 36.4 square miles of drainage area.
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The Mill River watershed is unique because it is the largest in the water supply system of the Water Authority holdings, because of the degree of urbanization within its boundaries, and because it has an extensive stratified-drift aquifer. An aquifer is the name for rock or soil that contains and transmits water and is therefore a source for underground water. An aquifer may be an underground pocket of gravel or sand, a layer of sandstone or a layer of cracked rock creating a pathway. Somewhere under these aquifers is rock that is impermeable and watertight. This is called bedrock. Water is stored in the Mill River aquifer which measures thirteen miles by one mile.
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This is a natural formation which keeps the Mill River flowing even in dry periods. This is the throughflow water that reaches the river in a few days to a week after the rains, but the water way deep in the ground, known as groundwater, may take months or years to reach the river. Very little water reaches streams by simply flowing over the ground surface.
The Mill River watershed property is quite visible. The river meanders to the right and left of Whitney Avenue from the Cheshire area down to the Whitney Dam. Lake Whitney is 2 1/2 miles long and approximately 1/2 mile wide. It has a capacity of 258 million gallons. The system derives its supply from two sources, surface water and groundwater.
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In highly urbanized areas, contamination of our water supply can be very serious. Problems with surface water can come from automobile exhaust emissions. Sometimes both road salt and even gasoline from leaky tanks can find their ways into groundwater. Old tires near dumpsites are a source of contamination. Noxious fumes, composed of sulfur dioxide and nitrogen dioxide, from factory smoke stacks as well as from car exhaust emissions, when combined with rainwaters, form acids which can change the chemical balance in water supplies. Ground-water problems are very serious because certain volatile organic chemicals do not dissipate readily underground.
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So first the environment and then the aquifer must be managed carefully to protect our vital groundwater. It is not so much the quantity that should be our concern, but the quality. We seem to have enough water not to have to worry about Ben Franklin’s warning, “When the well’s dry, we know the worth of water.” Water quality problems must be constantly monitored to keep our Hydrologic Cycle as safe as we can for the generations to follow.
Activities Suggested for the Mill River Watershed Unit:
Activity 1. Using your watershed map and with the aid of the Connecticut Geological Drainage Basin Map (or with the aid of the overhead provided in the teacher’s packet) shade in the area of the Mill River Watershed, locating the Mill River and the tributaries, especially Willow Brook and Eaton Brook. Also, label the Lake Whitney Dam.
Activity 2. A short field trip to the flood gates might be of interest. Go to the beginning (North side) of the Willow Street Bridge, across from a large ball field. Head for the big recreational house and find the path on the left which leads to the flood gates.*
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a. Take some specimens of water on both sides.
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b. Which way is the tide flowing?
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c. Are the banks of the river the same or different?
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d. Notice and collect some of the plants growing along the banks of the river. Identify plants.
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e. What kind of plants seem to predominate the river banks looking up stream?
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f. Do you see any evidence or animal life? (People catch bass on both sides of the flood gates!)
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g. Test water for salinity with a hydrometer (to measure specific gravity). One on loan upon request. Or use a little silver nitrate solution to get a precipitate (white indicates silver).
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h. Test for oxygen content either with Hach material or use a simple qualitative device using colorimetry with methylene blue (directions given upon request).
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i. Test for acidity with pH paper (given on request).
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*Refer to Pollution Diagram.
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Activity 3. A field trip to Sleeping Giant Park and to Cheshire to find the head water area for the system—also to look for historic sites in the vicinity (see History Unit).
Possibilities for an archaeological dig in one area.
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Directions:
In the Park, just off Mt. Carmel Avenue, is a foot path following the river north and on the right side. You will come to Axle Shop Pond and Munson’s Dam. Turning around and going to the left of the river, in the same general area are the remains of either a can or a sluice way for water to be channeled to a culvert. This whole area has many interesting things to see, such as iron bars sticking up, also the remains of a wall or possible foundation. There is also the remains of what might have been a flume. Notice the quality of the water as compared to the lower river.
Activity 4. Make a diagram showing means by which “ACID RAIN” forms.
Activity 5. Make a Rain Gage and collect data for two or three months. (Find directions with diagram of Rain Gage.) Get measurement in millimeters. Make a graph for converting mm to inches.
Activity 6. Directions given for reading contour maps.
Quinnipiac River (East Rock Park Association)
(figure available in print form)