Round Valley Reservoir, New Jersey, USA

Lake Locations:

USA - Mid-Atlantic - New Jersey - Skylands -

Round Valley Reservoir spans 2,350 acres in Hunterdon County, New Jersey. The reservoir fills the valley formed by the ring-shaped Cushetunk Mountain, which was once an active volcano. Named for the circular shape of the valley in which it sits, the reservoir is known for the exceptional clarity of its waters and its thriving fish population. With a maximum depth of 180 feet, it also New Jersey’s deepest lake.

Round Valley Reservoir was created in the 1960s by the New Jersey Water Authority. Because of the valley’s natural concave shape, just two dams and a dike were needed to enclose it completely, and the reservoir was flooded with 55 billion gallons of water. Today, Round Valley is a crucial part of the water supply system for central New Jersey, as well as a favorite recreation area.

Round Valley Reservoir offers some of the best fishing in the state. Nineteen species of fish inhabit Round Valley Reservoir, and on a warm summer day you will find anglers hoping to make a record catch. The reservoir is stocked yearly with rainbow trout and brown trout, and state records have been set at Round Valley for lake trout and brown trout, as well as freshwater eel and smallmouth bass. Also found in the lake are largemouth bass, pickerel, catfish, and yellow perch. Anglers can fly-fish for trout from the shore, or fish by boat. To preserve the purity of the reservoir’s waters, motorboats are restricted to engines of no more than 10 horsepower. Also welcome at the lake are canoes, kayaks, and sailboats.

Round Valley Reservoir’s clear blue water makes it ideal for scuba diving, skin diving, and snorkeling. The lake’s exceptional visiblity makes it easy for divers to study a wide variety of fish and plant life. With a maximum depth of 180 feet, there is plenty of room to explore. Round Valley also has a designated swimming area separate from the main reservoir. The public swimming beach is open from Memorial Day to Labor Day and has all the amenities necessary for some fun in the sun: restrooms, showers, concession stands, and even playgrounds and volleyball nets.

Nature lovers won’t be disappointed with a visit to Round Valley. The lake is surrounded by over 5,000 acres of woodlands, and birdwatchers can spot hawks, ospreys, loons, and herons hunting the lake’s waters. There have also been sightings of bald eagles nesting on nearby Cushetunk Mountain. Round Valley Recreation Area offers hiking opportunities for all skill levels, from the rugged nine mile Cushetunk Trail for skilled hikers, mountain bikers, and horseback riders, to the one mile Pine Tree Trail, best suited to birdwatchers and families. Nearby Cushetunk Mountain Nature Preserve offers more opportunities for hiking and mountain biking and some difficult mountain trail. In the winter months, visitors trade their hiking boots for ski boots, as Round Valley is transformed into a winter wonderland for skiing and sledding.

If camping is your passion, then Round Valley is the place for you. It is one of the few parks in the state to offer wilderness camping, with 85 tent sites that are accessible only by a three mile hike or by boat. These sites are equipped with fire pits, and water pumps and outhouses are available along the hiking trail. If these accommodations sound a little too basic, don’t worry: there are hotels and even a few bed and breakfasts just a short drive away.

Fishing, diving, camping, hiking–with such a wide variety of activities for all ages, the reason for Round Valley’s popularity is as clear as its waters. No matter what the season, Round Valley Reservoir is the perfect place to get away from it all.

Things to do at Round Valley Reservoir

  • Fishing
  • Boating
  • Sailing
  • Swimming
  • Beach
  • Canoeing
  • Kayaking
  • Snorkeling
  • Scuba Diving
  • Camping
  • Hiking
  • Biking
  • Horseback Riding
  • Hunting
  • Birding
  • Playground

Fish species found at Round Valley Reservoir

  • Bass
  • Black Bass
  • Brown Trout
  • Catfish
  • Eel
  • Lake Trout
  • Largemouth Bass
  • Perch
  • Pickerel
  • Pike
  • Rainbow Trout
  • Smallmouth Bass
  • Trout
  • Yellow Perch

Round Valley Reservoir Photo Gallery

Round Valley Reservoir Statistics & Helpful Links

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Lake Type: Artificial Reservoir, Dammed

Water Level Control: New Jersey Water Supply Authority

Surface Area: 2,350 acres

Shoreline Length: 12 miles

Normal Elevation (Full Pond): 381 feet

Minimum Elevation (Min Pond): 385 feet

Maximum Elevation (Max Pond): 361 feet

Average Depth: 60 feet

Maximum Depth: 180 feet

Water Volume: 168,788 acre-feet

Completion Year: 1965

Drainage Area: 5 sq. miles

Trophic State: Ogliotrophic

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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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