Seminole County samples monitoring wells at many of its sites to ensure no contamination of groundwater or surface water is incurred as a result of any of the County's activities. A total of 81 monitoring wells and 9 surface water sites are sampled periodically and tested for contaminants. The Upsala Transfer Station, for example, was formally a county landfill and continues to be monitored for possible groundwater contamination. Other sites include the Seminole County Landfill, the Greenwood Lakes and Northwest Regional Wastewater Treatment Plant re-use sites, Sylvan Lake Park and the Seminole County Softball Complex.