Lake Tappan, New Jersey & New York, USA

Lake Locations:

USA - Mid-Atlantic - New Jersey - Gateway - New York - Hudson Valley -

Also known as:  Tappan Lake, Lake Tappan Reservoir, Tappan Reservoir

Lake Tappan is one of a series of reservoirs that was created to deliver drinking water to the huge population of the New York City metro area. The lake contains about 1250 acres of water, and nearly 12 million gallons are released daily to the downstream Oradell Reservoir. It straddles the border of New Jersey and New York. The water level is controlled by United Water, a privately owned Utility Company who provides drinking water to over 7 million people. United Water was originally the Hackensack Water Company, and was formed in 1869.

Lake Tappan was formed in 1966 when the Tappan Dam was built on the Hackensack River. It was one of three additional reservoirs that were created when the original, the Oradell Reservoir (created in 1921), could no longer meet the demands of the local population.

The reservoir has caused several problems for the countryside upstream of it. Back-flooding has become a huge problem since the Tappan Dam was constructed. The effects are seen for about 100 miles – all the way to the Lake Deforest Dam.

Because the Lake is a Category One Protected body of water, there is no boating, swimming or wading allowed in the lake. Lake Tappan is listed as Category One because it supplies drinking water to the metro area. There can be nothing allowed on the lake that can harm the environmental status of the lake.

Recreation is allowed in the lake area, but a permit from United Water must be obtained first. The permit allows access to all of the reservoirs in the area – Oradell, Tappan, Lake DeForest and Woodcliff Lake. Lake Tappan has special wheelchair accessible docks, handicap parking and on-site services available for the comfort of those who need the services.

Fishing is allowed from the shore ONLY. A permit is required for anyone older than 16. Permits are checked regularly. You will find several species of fish in Lake Tappan: yellow and white perch, small and largemouth bass, catfish, sunfish and carp.

Lake Tappan is also a great place for avid ornithologists. Multiple types of birds have been spotted, including the Bald Eagle. The Tufted Titmouse, Red-tailed Hawk, Mute Swan and the Pied-Billed Grieb are among others that make their home around the reservoir.

A couple of important notes are that the reservoir is only open to visitors from the beginning of April to the end of November. Access to the lake area will not be permitted if the terror threat level is orange or higher. No one is permitted to take pictures on United Water Property.

The Tappan Reservoir is certainly an important part of daily life in the NYC Metro area, whether the residents there realize it or not. It is part of the gargantuan machine necessary to keep fresh drinkable water flowing through their pipes. Though it is vital to their existence, it is still a problem because the dams on the Hackensack have wreaked havoc on the natural ecosystem that has existed for centuries. Local watersheds are still trying to mend this issue, and will do so until they have a solution.

Things to do at Lake Tappan

  • Vacation Rentals
  • Fishing
  • Boating
  • Swimming
  • Birding

Fish species found at Lake Tappan

  • Bass
  • Black Bass
  • Carp
  • Catfish
  • Largemouth Bass
  • Perch
  • Sunfish
  • White Perch

Lake Tappan Photo Gallery

Lake Tappan Statistics & Helpful Links

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Lake Type: Artificial Reservoir, Dammed

Water Level Control: United Water

Surface Area: 1,255 acres

Normal Elevation (Full Pond): 44 feet

Minimum Elevation (Min Pond): 39 feet

Maximum Elevation (Max Pond): 55 feet

Average Depth: 21 feet

Maximum Depth: 43 feet

Water Volume: 10,741 acre-feet

Completion Year: 1968

Lake Area-Population: 32,000

Drainage Area: 49 sq. miles

Trophic State: Eutrophic

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Trophic State | LakeLubbers

Trophic State measures the level of algae and nutrients in a lake.

An oligotrophic lake is very clear (blue in color) and does not support much plant or fish life. A hyper-oligotrophic lake is the clearest of all lakes, and is nearly devoid of plants and fish.

A mesotrophic lake is slightly green and supports a moderate degree of plant and fish life. A lake's most desired trophic state is generally this mid-point - the mesotrophic state.

A eutrophic lake is somewhat murky and supports a large amount of plant and fish life. A hypereutrophic lake is clouded with algae, plant life, and fish life. A eutrophic or hyper-eutrophic lake can be difficult to navigate by boat - and is often an unpleasant place to swim.

The use of phosphorus-rich and nitrogen-rich fertilizer on lawns and golf courses surrounding a lake can cause it to become eutrophic or hypereutrophic.


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Catchment or Drainage Area | LakeLubbers

This is the surrounding area that drains into a lake, including land, rivers and their tributaries. This is also known as the lake's "catchment basin".

Small lakes at the highest peaks of mountains have small drainage areas. The world's oceans have the largest drainage areas.


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Lake-Area Population | LakeLubbers

This is the estimated number of people who live in a house with a view of a lake, plus those who self-describe the lake as their home, for example: "I live at Smith Mountain Lake."


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Water Residence Time | LakeLubbers

This is the estimated time that it takes for an amount of water equal to the entire volume of a lake to flow out of - or evaporate from - the lake.

Residence Time can be as short as a few days for fast-flowing small lakes, and can exceed 100 years for slow-flowing large lakes.


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Completion Year | LakeLubbers

This is the year that a reservoir was first filled to the reservoir's normal elevation - or the year that a natural lake was first dammed. A large reservoir can take more than a year to fill after its dam is first closed.

The Grand Anicut in southern India is generally considered the world's oldest dam that still operates. Grand Anicut was constructed in the second century BC. It now impounds an irrigation network that includes roughly one million acres.

You can find many of the the world's newest reservoirs on LakeLubbers. Many of the world's oldest reservoirs appear on the last page of that list.


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Water Volume | LakeLubbers

This is the estimated volume of water that a lake contains -- measured at the lake's normal elevation. By this measure, the world's largest freshwater lake is Siberia's Lake Baikal.

You can find many of the the world's largest lakes (by water volume) on LakeLubbers.

Water Volume can be measured in acre-feet, in cubic miles, or in cubic kilometers. One acre-foot is the amount of water needed to cover one acre (43,560 square feet) to a depth of one foot. One cubic mile equals 3,379,200 acre-feet. One cubic kilometer equals 810,713 acre-feet.

1 acre-foot is equal to 325,851 US gallons. Siberia's Lake Baikal contains about 6,276,367,740,000,000 gallons of freshwater - nearly 1 million gallons for every living person on earth.

The other - and more widely used - measure of a lake's size is the lake's surface acreage. By that measure, the world's largest freshwater lake is North America's Lake Superior.


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Maximum Depth | LakeLubbers

This is the estimated greatest depth of the water in a lake -- measured at the lake's normal elevation. The world's deepest lake is Siberia's Lake Baikal; that lake's maximum depth is estimated at 5,314 feet.

You can find many of the the world's deepest lakes on LakeLubbers. If you select the last page of that list, you will find the (maximum depth of) the shallowest lakes in our database.


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Average Depth | LakeLubbers

This is the estimated average depth of the water in a lake -- measured at the lake's normal elevation. If the water volume and surface area of a lake are known, an estimate of the lake's average depth can be calculated:

Water volume ÷ Surface Area = Average Depth

Example: 1,000,000 acre-feet ÷ 20,000 acres = 50 feet average depth


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Maximum Elevation | LakeLubbers

This is a lake's highest water level, measured by the lake's surface distance above sea level, that can occur during flooding. A lake's highest possible maximum elevation is usually the top of the lake's dam or spillway.

At lakes that include residential development, government regulations usually forbid the construction of homes below a lake's maximum elevation.


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Minimum Elevation | LakeLubbers

This is a lake's lowest water level, measured by the lake's surface distance above sea level, that can be reasonably expected to occur. Low lake levels can occur due to deliberate seasonal draw downs for irrigation or impending snow melt, reduced water inflows, drought and evaporation, residential or commercial water demands, and hydropower generation.

Some lakes' minimum and maximum elevations are virtually the same. Lakes that generate hydropower may vary by several feet - according to power demand. Lakes whose primary purpose is to prevent flooding can seasonally vary by 100 feet or more.

When some lakes reach their minimum elevation, their boat ramps may not be long enough to permit boat access - and boats docked on shallow parts of the lake may end up on dry ground. In those cases, kayakers and shore-based anglers may be among the few happy recreational users of the lake.


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Normal Elevation | LakeLubbers

This is a lake's normal water level, measured by the lake's surface distance above sea level. For a reservoir, this water level is also known as "full pond" or "full pool".

You can find many of the world's highest-elevated lakes on LakeLubbers. Lakes with the lowest elevations (known by LakeLubbers) are shown on the final page of that list.


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Shoreline Length | LakeLubbers

This is the length of the exterior shoreline around a lake - measured at the lake's normal elevation. The shoreline length can be considerably shorter or longer when lake water levels are lower or higher than normal.

A lake with many coves has a much longer shoreline than a lake of similar surface area that is nearly circular in shape.

When known, the shoreline miles that we report in our statistics include only the lake's exterior shoreline, and exclude the shorelines of islands located within a lake's boundaries. In lakes with many islands, those islands' combined shorelines may exceed a lake's exterior shoreline.

You can find many of the world's longest-shoreline lakes on Lakelubbers.


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Surface Area | LakeLubbers

This is the area (acreage, square kilometers, etc.) of the top surface area of a lake - measured at a lake's normal elevation. The surface area can be considerably smaller or larger when lake levels are lower or higher than normal. North America's Lake Superior is the world's largest freshwater lake by this measure.

The other measure of a lake's size is the lake's water volume. By that measure, the world's largest freshwater lake is Lake Baikal in Siberia.

You can find many of the world's largest lakes (acres) on Lakelubbers. There is no widely-accepted minimum surface area that defines a lake. What Lakelubbers describes as a lake, you might call a pond. The smallest lake that Lakelubbers currently includes is Hawaii's 2-acre Lake Waiau.


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Water Level Control | LakeLubbers

This is the organization that controls water releases or outflows from the lake or reservoir. In the USA, this is often the US Army Corps of Engineers, a power company, a municipal water system, an irrigation district, or a paper manufacturing company. In the case of private or gated lakes, a homeowners' association may be the lake's controlling authority.

Many lakes cross borders, including North America's Great Lakes. The control of such lakes and their coveted freshwater may be amicably shared - or hotly disputed.

"Water wars" continue at many lakes as growing populations and crop irrigation needs compete for the freshwater that lakes contain.


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Lake Type | LakeLubbers

There are 3 basic types of lakes that are currently included on LakeLubbers. 2 types may be dammed or not dammed, producing 5 classifications.

- A Reservoir is a man-made freshwater lake that is usually created by damming rivers.

- A Natural Freshwater Lake occurs naturally - often by glacial activity - and has a salinity of less than 30 parts per thousand. It may be dammed to produce electricity or for other reasons.

- A Natural Saltwater Lake occurs naturally and has a salinity of more than 30 parts per thousand (ppt). It may be dammed.

"Brackish" water may be categorized as freshwater or saltwater, depending on its salt content (salinity). Oligohaline water has less than 15 ppt of salt. Mesohaline water has 15-29 ppt. Polyhaline has 30-335 ppt.


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