SCHEMA:
CREATE TABLE table_18600760_15 (water__sqmi_ VARCHAR, county VARCHAR, geo_id VARCHAR)
USER:
How many square miles of water is in Ramsey County with a geo id larger than 3807159460.0?

QUERY:
SELECT water__sqmi_ FROM table_18600760_15 WHERE county = "Ramsey" AND geo_id > 3807159460.0