Mystic Dam facts for kids
Quick facts for kids |
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Mystic Dam
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The historic dam alongside modernizing construction in 2010
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 Location in Massachusetts
Location in the United States
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| Location | Arlington / Medford, Massachusetts |
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| Built | 1864 |
| Architect | Barnes, Kingsley & Co. |
| MPS | Water Supply System of Metropolitan Boston MPS |
| NRHP reference No. | 89002282 |
| Added to NRHP | January 18, 1990 |
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Mystic Gatehouse
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View of the gatehouse and the Upper Mystic Lake
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| Location | Medford, Massachusetts |
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| Built | 1862 |
| MPS | Water Supply System of Metropolitan Boston MPS |
| NRHP reference No. | 89002284 |
| Added to NRHP | January 18, 1990 |
The Mystic Dam and its gatehouse are important historical structures. They are located between the Lower and Upper Mystic Lakes in the suburbs north of Boston, Massachusetts. These structures were built a long time ago to help manage the water supply for the city of Charlestown. Charlestown was a separate city back then, but it's now part of Boston.
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The Mystic Dam and Gatehouse
The Mystic Dam was built between 1864 and 1865 by the Charlestown Water Commission. It was placed at a narrow spot between the Lower and Upper Mystic Lakes. One end of the dam is in Arlington, and the other end is in Medford. The water system that the dam was part of later joined bigger organizations. These include the Metropolitan District Commission (MDC), which is now known as the Massachusetts Water Resources Authority (MWRA) and the Massachusetts Department of Conservation and Recreation (DCR).
How the Dam Was Built
When it was first built, the dam was very long, over 1,500 feet (457 meters). It was also about 16 feet (5 meters) high. Most of its length, about 1,000 feet (305 meters), was made of earth. This earth was covered with rocks (called riprap) and a special type of clay (called puddle clay) to make it strong and waterproof.
Near the middle of the dam, there is a spillway. A spillway is like a controlled overflow area for water. This part was built with strong granite blocks. These blocks had grooves to hold "stop logs." Stop logs are like big wooden planks that can be put in place to control the water flow. A wooden walkway with a railing used to run across the top of the dam.
The Gatehouse and Fish Ladder
A special building called a gatehouse was built on the Medford side of the dam. This gatehouse connected the upper lake to a brick-lined tunnel called an aqueduct. The aqueduct carried water all the way to Charlestown. The area of the lake held back by the dam is about 186 acres (75 hectares).
A wooden fish ladder was also built. A fish ladder helps fish swim past the dam to lay their eggs. However, this original fish ladder was removed later on.
Keeping the Dam Safe
Both the Mystic Dam and its gatehouse were recognized as important historical sites in 1990. They were added to the National Register of Historic Places.
By the early 2000s, people noticed that the dam was not in very good shape. Its stone parts were breaking, and there was erosion. A big storm in 2006 caused flooding in the nearby areas. This event showed that the dam might not be able to handle a lot of water. If it failed, it could cause huge floods downstream.
Because of this, a lot of work was done on the dam between 2010 and 2012.
- A new spillway was built next to the old one.
- The banks of the dam and the areas near the upper lake were repaired.
- A brand new fish ladder and a bridge were constructed.
- The historic gatehouse was also fixed up.
- Modern controls were added to the gatehouse. These new controls make it much easier to manage the water levels behind the dam.
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After the 2010 renovations.
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The gatehouse.
