Cottage Lake, WA has a population of 23,845 and is the 1,836th largest city in the United States. The population density is 1,048 per sq mi which is 984% higher than the Washington average and 1057% higher than the national average. The median age in Cottage Lake is 43 which is approximately 15% higher than the Washington average of 38. In Cottage Lake, 69% of the population over 15 years of age are married, 87% speak English and 3% speak Spanish. 43% of Cottage Lake residents were born in Washington, 43% were born out of state, 1% were born outside of the United States and 12% were foreign born.