"Brackish water" refers to a type of water that is not completely salty like seawater, but is also not entirely fresh like water from a river. It is a mixture of saltwater and freshwater, creating a slightly salty taste. Full definition
Like the ancestors of modern terrestrial creatures, Qingmendous dwelled in brackish waters of lagoons, bays and deltas — within spitting distance of land. (washingtonpost.com)
The vaquita, a porpoise living in brackish waters where the Colorado River empties into the Gulf of California, is critically endangered, biologists say, depleted by fishing nets and the disruptions in the great river's flow in the 20th century from dam construction. (dotearth.blogs.nytimes.com)
Our toilets are serviced with brackish water from a shallow well to further minimize our fresh water utilizations. (tflats.com)