It forms occasionally in Badwater Basin after heavy rainfall, but at its maximum extent during the so-called "Blackwelder stand," ending approximately 120,000 years before present, the lake covered much of Death Valley with a surface area of 1,600 square kilometres (620 sq mi).

The lake and its substantial catchment favoured the spread of a number of aquatic species, including some lizards, pupfish and springsnails.

[9] More recently, renewed scientific interest has stemmed from the fact that Lake Manly formerly drained the area of Yucca Mountain, a proposed nuclear waste repository.

[27] Faulting has caused a progressive drop in elevation of the floor of Death Valley, keeping pace with sedimentation, though the exact rates are not known.

[43] Some landforms indicative of lacustrine deposition have been found at altitudes of 595 metres (1,952 ft) (the overflow height) above sea level around Death Valley but they could also be the consequences of non-lacustrine processes.

[47] Currently a salt pan fills Death Valley, with an average surface altitude of −75 metres (−246 ft).

[22] One island existed close to Beatty Junction,[48] with two more at Shoreline Butte in the southernmost point of the lake;[49] the northern foot of the Avawatz Mountains may have formed a peninsula on the southern shore.

[50] No river deltas or other embankments have been found at Lake Manly's shorelines; their formation was likely hampered by unstable water levels.

[66] The total surface area of Lake Manly's catchment was about 65,806 square kilometres (25,408 sq mi).

[69][82] Little evidence of such spillover remains, such as delta-like deposits at Anvil Spring Canyon,[31] the distribution of fish fossils in the various waterbodies,[67] ostracod data and the presence of northupite;[83] strontium isotope data suggest that the Owens River system was a minor contributor to Lake Manly.

[88] Whether Owens River water reached Lake Manly between 1.2 and 0.6–0.51 million years ago is unclear.

[108][102] According to early researchers, Lake Manly had no outlet and its water level would have been governed exclusively by the balance of inflow and evaporation.

[5] Biological evidence, however, such as fossil pupfish, indicates that connections to the Colorado River existed,[31] then ceased about 3-2 million years ago.

[44] Overall though scientific consensus tends to view any connection between Lake Manly and the Colorado more recent than 3 million years ago as unlikely.

[123][124] The composition of lake deposits suggests that calcium-rich springs associated with a crustal magma chamber in the southern Death Valley contributed sizable quantities of water to the lake;[125] this magma chamber is also correlated to a 700,000 years old cinder cone in southern Death Valley.

[135] Based on hydrological modelling, a temperature drop of about 10 °C (18 °F) and 2.5 times today's precipitation would be needed to recreate the last highstand of Lake Manly.

[137] Later research reduced this requirement to about 14–27 metres per second (46–89 ft/s),[138] which is consistent with estimated present day wind speeds in Death Valley.

[121] The Lake Manly drainage system facilitated the spread of species of the genera Cyprinodon and Empetrichthys in the region,[66] and of pupfish more generally.

[155] Lake Manly existed during the late Pleistocene,[4] and was at first considered to be an early Wisconsin glaciation (Tahoe stage) phenomenon.

[165] According to sedimentation patterns, a southeastward flowing river occupied northern Death Valley during the late Miocene,[68] and was gone by 3.35 million years ago.

[167] A Pliocene stage is documented in southern Death Valley,[27] and a lake in the Furnace Creek basin of northern Death Valley reached a highstand 3.35 million years ago;[168] a number of tephra layers provide controls on the ages of this lake.

Tephra interbedded with lake deposits indicates that a pre-Lake Manly existed between 1.2–0.8 million and 665,000 years before present.

[179] A brief dry period may have occurred 148,000 years ago, possibly caused by a temporary damming of the Amargosa River.

[27] The Blackwelder highstand was probably not stabilized by overflow seeing as the only spillway close to Ludlow is about 595 metres (1,952 ft) high above sea level – considerably higher than the Blackwelder highstand could plausibly be[39] – and the highest shorelines at Shoreline Butte and Lake Mojave are considerably lower.

[35] Additionally, the development of stable shorelines does not by default require an overflow, as demonstrated by the Dead Sea and its precursor Lake Lisan.

[69] Ostracod fossils dated between 129,000 and 123,000 years ago indicate that Death Valley was wetter than today and supported several hydrological environments.

[194] This drying event separated various Cyprinodon populations from each other, triggering the evolution of individual species with restricted distribution.

[195] Based on the state of preservation of shoreline deposits (e.g., at Hanaupah Fan), the retreat of the lake was probably much faster than its growth.

[201] Current evaporation rates and climate conditions do not allow the existence of perennial lakes in Death Valley.

[206] In 2023 and 2024, the valley floor received 4.9 inches over a period of six months, forming a shallow lake deep enough for kayaking.