Lake Ogawara, Brackish lake in Tōhoku, Japan

Lake Ogawara is a brackish lake in Aomori Prefecture, Japan's eleventh largest by area at 63.2 square kilometers. It is shallow for about 200 meters from the shore, then drops to a maximum depth of 25 meters. The surface lies at sea level, and the lake narrows toward the north, where wooded slopes and fields meet the water.

Lake Ogawara formed about 3,000 years ago when a sand bar closed off a marine bay; Jōmon-period shell middens, notably at the Futatsumori Site on the west bank, show settlement since prehistoric times. In the 1970s the government began a project to convert the brackish lake to fresh water for drinking and irrigation, abandoned in December 1996 when projected demand fell short. During World War II, Misawa Airfield units of the Imperial Japanese Navy Air Service practised here for the attack on Pearl Harbor because the lake's depth resembled that of Pearl Harbor.

The name is said to derive from Ainu words such as "okara", meaning to go around. Until 1 January 1958 the lake was called Ogawara-numa; the adjacent Ogawara Station still keeps the original reading "Kogawara". A legend tells of two sisters, Tamayo-hime and Katsuyo-hime, who drowned themselves in two ponds after learning of their father's death; the younger sister's pond is today's Lake Ogawara, and the sisters are honoured at Hime-to Daimyōjin and Hironuma Daimyōjin.

The lake is shallow for about 200 metres from the shore before the depth drops sharply, so bathers should watch for the sudden drop-off. In winter the surface freezes and hole-fishing for smelt is possible. The southern shore by Misawa Air Base is off-limits to the public.

The lake is one of the few places in Japan where the brackish-water green alga Wittrockiella salina has been confirmed, a first for the country. Its shores were also chosen in 1996 as one of the 100 Soundscapes of Japan for the calls of wild birds.