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Lake Anna

Lake Anna is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Lake Anna rather than just read about it. In short: Lake Anna is one of the largest freshwater inland reservoirs in Virginia, covering an area of 20 sq mi (52 km2), and located 72 miles (116 km) south of Washington, D.C., in Louisa and Spotsylvania counties (and partially in Orange County at the northern tip). The lake is easily accessible from Fredericksburg, Richmond, Charlottesville, Northern Virginia, and Washington, D.C., and is one of the most popular recreatio…

Lake Anna — main illustration
Lake Anna — illustration

Key takeaways

  • Lake Anna belongs to physics; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Lake Anna to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Lake Anna from memory before moving on to harder problems.

Reference excerpt

Lake Anna is one of the largest freshwater inland reservoirs in Virginia, covering an area of 20 sq mi (52 km2), and located 72 miles (116 km) south of Washington, D.C., in Louisa and Spotsylvania counties (and partially in Orange County at the northern tip). The lake is easily accessible from Fredericksburg, Richmond, Charlottesville, Northern Virginia, and Washington, D.C., and is one of the most popular recreational lakes in the state.

History The reservoir is formed by the North Anna Dam on the North Anna River at 38°00′47″N 77°42′46″W. In 1968, Virginia Electric and Power Company (now Dominion) purchased 28 sq mi (73 km2) of farmlands in three counties along the North Anna and Pamunkey rivers. The aim was to provide clean, fresh water to help cool the nuclear power generating plants at the North Anna Nuclear Generating Station adjacent to the lake. By 1972, the lake bottom was cleared of all timber, and the dam was nearing completion. It was projected to take three years to completely fill the lake, but with the additional rainfall from Hurricane Agnes, the lake was full in only 18 months. The first communities began to spring up around the lake at that time, and now some 120 different communities surround its shores. In June 1978, the first of the two reactors went into commercial operation. The second unit followed in December 1980.

Description Lake Anna is approximately 17 miles (27 km) long from tip to tip, with 200 miles (320 km) of shoreline. The lake is divided into two sides by three stone dikes. The public side (also known as the "cold" side) is roughly 9,000 acres (36 km2), while the private side (known as the "warm" side) is roughly 4,000 acres (16 km2). The private side is formed of three main bodies of water, connected by navigable canals. This side has no marinas or public access ramps; only property owners and North Anna Power Station employees have access to the waters on the private side. The public side has several marinas and boat launches, including a boat ramp at an adjacent state park. The public side sees significantly higher boat traffic compared to the private side, especially on summer weekends. The public side is known as the "cold" side because it provides water to cool the generators at the power plant; the private or "hot" side receives warm water discharge from the power plant. The private side can be substantially warmer than the public side, especially near the discharge point, where it can be too hot for swimming. The private side has an extended water sports season. Some water circulates back out of the private side into the public side through underground channels; consequently, the public side is warmer in the southern area near the dam. In the winter, some fish migrate to these warmer waters. Preliminary steps to add a third reactor have led to protests by environmentalists and property owners, who fear a subsequent increase in the water temperature and a decrease in the water level, particularly on the private side. According to Dominion, the water discharged from the plant is usually about 14 °F (7.8 °C) warmer than the intake water.

North Anna Dam

The dam creating the lake, North Anna Dam, is a 5,000-foot-long (1,524 m) and 90-foot-high (27 m) earthen embankment dam. It is 30 feet (9 m) wide at its crest and sits at an elevation of 265 feet (81 m) above sea level. The dam's spillway is located in the center of its body and is 200 feet (61 m) wide, containing three main 40-foot-wide (12 m) and 30-foot-high (9 m) radial gates. Two smaller 8.5-foot (3 m) wide and tall gates on the outer edges of the spillway section maintain normal discharges. The nominal water level at the dam is 250 feet (76 m) above sea level. The dam's hydroelectric power plant is located on the west side of the spillway and is supplied with water via a 5-foot-diameter (2 m) penstock. The plant consists of two small open runner turbine-generators, the larger with a 775 kW capacity and the smaller rated at 225 kW for a combined installed capacity of 1 megawatt.

Wildlife Fish species present in Lake Anna include largemouth bass (Micropterus salmoides), bluegill (Lepomis macrochirus), redear sunfish (L. microlophus), channel catfish (Ictalurus punctatus), white catfish (Ameiurus catus), yellow bullhead (A. natalis), brown bullhead (A. nebulosus), black crappie (Pomoxis nigromaculatus), white perch (Morone americana), American gizzard shad (Dorosoma cepedianum), threadfin shad (D. petenense), blueback herring (Alosa aestivalis), creek chubsucker (Erimyzon oblongus) and white sucker (Catostomus commersonii). Striped bass (Morone saxatilis) and hybrid striped bass are maintained by stocking. Blue catfish (Ictalurus furcatus), grass carp (Ctenopharyngodon idella) and saugeye may be present due to past introduction. As of 2017, the exotic northern snakehead (Channa argus) has established a self-sustaining population in Lake Anna. Species of submerged aquatic vegetation in the lake include Hydrilla verticillata, southern naiad (Najas guadalupensis) and Chara sp. American waterwillow (Justicia americana) grows as an emergent plant.

See also Gold mining in Virginia Bumpass, Virginia Jerdone Castle

References

Illustrations

Lake Anna illustration
Lake Anna: North Anna Dam
North Anna Dam

Worked examples

Example 1 — a first encounter with Lake Anna

Start with the simplest possible case. Write down what Lake Anna claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Lake Anna before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Lake Anna ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Lake Anna

In research
Lake Anna appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Lake Anna in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Lake Anna is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bodies of water of Louisa County, Virginia, Bodies of water of Orange County, Virginia, Bodies of water of Spotsylvania County, Virginia, so understanding it makes those chapters shorter.
In everyday life
Look for Lake Anna outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Lake Anna in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Lake Anna means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Lake Anna out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Lake Anna in simple terms?

Lake Anna is one of the largest freshwater inland reservoirs in Virginia, covering an area of 20 sq mi (52 km2), and located 72 miles (116 km) south of Washington, D.C., in Louisa and Spotsylvania counties (and partially in Orange County at the northern tip). The lake is easily accessible from Fred…

Why does Lake Anna matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Lake Anna?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Lake Anna.

Tags

  • Bodies of water of Louisa County, Virginia
  • Bodies of water of Orange County, Virginia
  • Bodies of water of Spotsylvania County, Virginia
  • Cooling ponds
  • Dominion Energy
  • Protected areas of Louisa County, Virginia
  • Protected areas of Orange County, Virginia
  • Protected areas of Spotsylvania County, Virginia
  • Reservoirs in Virginia

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