Colorado Lagoon is a 29 acres (12 ha) public park in the Alamitos Heights neighborhood of Long Beach, California.

The lagoon originally opened up into Alamitos Bay, but a bulkhead and tide gates were built in 1932 that made Colorado Street able to cross the body of water.

The park became less popular for swimming in the 1960s after the channel emptying into Alamitos Bay was turned into a long tunnel that was to be used for a planned freeway, which was canceled.

Los Angeles County funded a project to divert 40% of stormwater that would have gone into the lagoon to Long Beach Marine Stadium.

The California State Water Resources Control Board granted the city 5.1 million in 2011 to take sediment out, plant native species near the lagoon and remove invasive ones like cheeseweed, and install devices reducing pollution, amongst other upgrades.

[13] Construction began in 2020 when non-native trees were removed from the park,[14][15] although the COVID-19 pandemic and supply chain disruptions delayed any parts of the channel being built until 2022.

Birds such as grey plover, brown pelican, California gull, double-crested cormorant, great blue heron, great egret, American coot, red-breasted merganser, snowy egret, tricolored heron, spotted sandpiper, western sandpiper, least sandpiper, Canada goose, long-billed curlew, osprey, northern rough-winged swallow, golden-crowned sparrow, western kingbird, swinhoe's white-eye, killdeer, red-tailed hawk, Cooper's hawk, and red-shouldered hawk, can also be commonly found at the park[21] and bees and butterflies like fiery skipper are a frequent sight.

[22] Borders of the water area contain plants of the coastal sage scrub plant community like toyon, Menzies' goldenbush, California sunflower, dune buckwheat, giant coreopsis, hollowleaf annual lupine, spotted locoweed, coastal tidytips, common deerweed, desert wishbone-bush, beach suncup, round-tooth snake-lily, California poppy, California brittlebush, and purple Chinese houses and change into a salt marsh habitat as it gets closer to the water.