# 10 largest lakes in Nebraska

> Nebraska's biggest lakes are mostly reservoirs built to store water, reduce flood risk or support power generation. Using the full surface of any lake that touches Nebraska, Lewis and Clark Lake ranks first at about 31,000 acres. Lake McConaughy follows closely at...

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Byline: ARGO.net Editorial Team
Published: 2026-08-21T23:10:10+00:00
Categories: Statistics, Water

![Aerial view of Lake McConaughy in Nebraska](https://www.argo.net/wp-content/uploads/2026/08/authority_featured_lake_mcconaughy_nebraska.jpg)

Nebraska's biggest lakes are mostly reservoirs built to store water, reduce flood risk or support power generation. Using the full surface of any lake that touches Nebraska, **Lewis and Clark Lake ranks first at about 31,000 acres**. Lake McConaughy follows closely at 30,000 acres when full, while Harlan County Lake is a distant third at 13,250 acres.

The ranking includes entire shared border lakes, so all of Lewis and Clark Lake counts even though part of it lies in South Dakota. Readers comparing lists may see Lake McConaughy called Nebraska's largest reservoir. The [Nebraska Game and Parks Commission](https://outdoornebraska.gov/location/lake-mcconaughy/) uses that description for the largest reservoir wholly associated with the state, while its park guide calls the border-spanning Lewis and Clark Lake Nebraska's second largest reservoir. The surface-area rule used here resolves that naming conflict consistently.

All figures below are normal-pool or full-pool values, with other commonly published approximations used where necessary. Nebraska's irrigation reservoirs can shrink substantially during summer withdrawals or drought. Their live shorelines may cover far less water than the design figures suggest. For a continental sense of scale, even Nebraska's leaders are small beside the [largest lakes in North America](https://www.argo.net/10-largest-lakes-in-north-america-ranked-by-surface-area/).

## How the lakes were ranked

This list compares **water-surface area in acres** at a normal or full operating pool. Storage volume in acre-feet does not affect the order. Neither does the area of surrounding recreation land or the wider watershed.

When agencies publish slightly different surface figures, the ranking uses a clearly identified state or federal figure that fits the same full-pool approach. Reservoir area changes with elevation. Sediment accumulation and operating decisions can also move the shoreline, so the numbers describe a reference condition rather than today's lake.

## 1. Lewis and Clark Lake, 31,000 acres

Lewis and Clark Lake stretches for about 25 miles behind Gavins Point Dam on the Missouri River. The reservoir straddles Nebraska and South Dakota, with Nebraska shoreline extending through Cedar and Knox counties. The [U.S. Army Corps of Engineers lists **31,000 surface acres**](https://www.nwo.usace.army.mil/Media/Fact-Sheets/Fact-Sheet-Article-View/Article/487639/gavins-point-project-statistics/) at its reference pool, along with roughly 90 miles of shoreline and a maximum depth of 45 feet.

Counting the whole border lake places it first in this ranking by about 1,000 acres. Sediment carried by the Missouri and Niobrara rivers has accumulated in the reservoir's upstream reaches, where the broad lake grades into shallower delta habitat. The dam forms the lowest and smallest-storage reservoir in the six-dam Missouri River mainstem system, even though its surface exceeds every lake lying entirely within Nebraska.

## 2. Lake McConaughy, 30,000 acres

Lake McConaughy covers [**30,000 surface acres** at its normal full-pool elevation](https://outdoornebraska.gov/wp-content/uploads/2024/04/McConaughy-2023-survey-summary-handout.pdf) of 3,265 feet. Kingsley Dam impounds the North Platte River northeast of Ogallala, creating a reservoir that stores irrigation water and supports hydropower operations. Its long open basin and pale sand shoreline have made "Big Mac" Nebraska's best-known large lake.

The full-pool number can differ sharply from conditions on a given day. Nebraska fisheries staff reported that the surface contracted to about 12,400 acres at the record-low 2004 elevation, only 41 percent of its normal full-pool area. Such changes alter spawning habitat and boat access. They also change the amount of shallow water warmed by summer sun. Lake McConaughy's scale remains modest beside the glacial basins described in [how the Great Lakes formed](https://www.argo.net/how-the-great-lakes-formed/).

## 3. Harlan County Lake, 13,250 acres

Harlan County Lake spreads across about [**13,250 acres** under the Corps of Engineers' published figure](https://www.nwk.usace.army.mil/Locations/District-Lakes/Harlan-County-Lake/). The dam crosses the Republican River near Republican City in south-central Nebraska. Congress authorized the project after the destructive Republican River flood of 1935 and the completed reservoir began storing water in the early 1950s.

Flood reduction and irrigation both influence its water level. The multipurpose pool supplies farms in Nebraska and Kansas, so dry years can expose large flats as irrigation releases lower the lake. Other Nebraska sources round the lake to 13,500 acres or report 13,338 acres at full pool. This list uses the Corps' current project-page figure for consistency with the agency operating the dam.

## 4. Calamus Reservoir, 5,123 acres

Calamus Reservoir covers [**5,123 acres** in the Nebraska Sandhills](https://outdoornebraska.gov/location/calamus-reservoir/) near Burwell. Virginia Smith Dam captures off-season flow from the groundwater-fed Calamus River, then releases stored water during the irrigation season. The dam was completed in 1986, making Calamus much younger than the large Republican River reservoirs farther south.

Groundwater keeps the incoming river comparatively clear and steady, while the reservoir's operating cycle still changes shoreline position. Nebraska Game and Parks also reports 31 miles of shoreline and 119,469 acre-feet of storage. The latter measures water volume and is excluded from the size ranking. A similar surface-area method will let readers compare the planned guide to the [largest lakes in Oklahoma](https://www.argo.net/10-largest-lakes-in-oklahoma/).

## 5. Swanson Lake, 4,974 acres

Swanson Lake, also called Swanson Reservoir, occupies about [**4,974 surface acres** at its published recreation reference](https://usbr.gov/gp/recreation/trnerec.html). Trenton Dam holds back the Republican River a few miles west of Trenton. The Bureau of Reclamation built the project as part of the Frenchman-Cambridge Division, with irrigation storage and flood management among its main functions.

A 2011 Reclamation survey calculated 4,952 acres at the conservation elevation after updating underwater contours. The small difference from 4,974 acres reflects newer bathymetry, shoreline erosion and accumulated sediment. This ranking retains the widely used 4,974-acre facility figure, while recognizing that drought and irrigation withdrawals can reduce the lake far below either reference.

## 6. Sutherland Reservoir, 3,017 acres

Sutherland Reservoir covers approximately [**3,017 acres** near the town of Sutherland](https://digital.outdoornebraska.gov/i/1502490-nebraska-state-parks-guide/70). It belongs to a linked canal and reservoir system on the Platte River and serves as a cooling reservoir for Nebraska Public Power District's Gerald Gentleman Station. Water circulating through the power plant returns to the reservoir before continuing through the system.

Its engineered role produces a different setting from an irrigation impoundment built directly across a major river. Canal deliveries influence the pool and the reservoir's open shape leaves much of its surface exposed to western Nebraska winds. The 3,017-acre figure comes from Nebraska's state parks guide and describes lake area rather than the much smaller state recreation parcel along its shore.

## 7. Merritt Reservoir, 2,906 acres

Merritt Reservoir reaches about [2,906 surface acres](https://usbr.gov/gp/recreation/mrnerec.html) southwest of Valentine. Merritt Dam impounds the Snake River near its meeting with Boardman Creek, creating a deep, branching reservoir among the Sandhills. Reclamation built it for irrigation storage and Nebraska Game and Parks manages the surrounding recreation and wildlife lands.

Recent state fisheries material describes 2,905 acres of water, a one-acre difference caused by rounding. Both figures represent essentially the same full-pool footprint. Snake River and Boardman Creek inflows help refill the reservoir, while seasonal irrigation demand can pull the shoreline away from coves and ramps. The region's sparse artificial lighting also earned the recreation area an International Dark Sky Park designation.

## 8. Sherman Reservoir, 2,845 acres

Sherman Reservoir has a published full-pool area of [2,845 acres](https://digital.outdoornebraska.gov/i/1502490-nebraska-state-parks-guide/69). Sherman Dam sits on Oak Creek northeast of Loup City, yet most lake water arrives through a canal from the Middle Loup River. That diversion fills long side bays cut into the area's loess terrain.

The branching outline produces about 77 miles of shoreline when the reservoir is full, an unusually large amount for its surface area. Summer irrigation drawdown changes the extent of shallow coves and shoreline erosion has required habitat work. Nebraska's aquatic-habitat program added breakwaters and improved access. Excavated material formed an island that reduces wave damage while furnishing fish habitat.

## 9. Harry Strunk Lake, 1,850 acres

Harry Strunk Lake, widely known as Medicine Creek Reservoir, covers approximately [1,850 surface acres](https://usbr.gov/gp/nkao/docs/medicine_creek_appraisal.pdf) near Cambridge. Medicine Creek Dam was completed in 1949 as another component of the Frenchman-Cambridge Division. Its conservation pool stores water for irrigation, with flood control provided at higher elevations.

Some lake references use the dam's official reservoir name, while park material commonly uses Medicine Creek. Both names describe the same impoundment. Reclamation identifies 2,366.1 feet as the normal water-surface elevation and the 1,850-acre estimate corresponds to the familiar conservation-pool footprint. The actual area recedes when dry conditions and water deliveries lower the elevation.

## 10. Branched Oak Lake, 1,800 acres

Branched Oak Lake rounds out the list with approximately [1,800 acres of water](https://outdoornebraska.gov/location/branched-oak/). The reservoir lies northwest of Lincoln in the Salt Creek watershed and is the largest lake in eastern Nebraska. Its location near the state's largest population center gives it a different use pattern from the more remote western reservoirs.

The 1,800-acre estimate places Branched Oak just above 1,707-acre Enders Reservoir and lakes near 1,600 acres, including Lake Maloney and Box Butte Reservoir. A few acres of variation would not change its tenth-place position under the cited figures. Surface-area rankings for dry-country reservoirs always remain approximations, a consideration that also applies to the planned comparison of the [largest lakes in Utah](https://www.argo.net/10-largest-lakes-in-utah/).