On average, pond installation costs $3,362 or between $1,220 and $5,588. Specialty projects, such as a koi pond or natural swimming pool, might run $5,000 to $60,000 or more. Artificial lakes cost $4,000 to $15,000 per acre, or more if you add fish or water features. Expect most small projects to fall between $2.50 to $7.15 per square foot.