Simplify the following text for a Grade 4 native English-speaking person.
Original: The first 1 m stretch of the Klamath River is known as the Link River . Not long after , however , the river is impounded in a 18 m-long reservoir near Klamath Falls , Lake Ewauna , where it receives the Lost River and passes the nearly-dry bed of Lower Klamath Lake .
Simplified: The Klamath River is a long river in California .