Iowa DNR and local partners to manage the invasive curlyleaf pondweed at Iowa Great Lakes 3/31/2020 12:42:00 PM View Count 2863 Spirit Lake, Iowa - The Iowa Department of Natural Resources (DNR), working with the East Okoboji Lakes Improvement Corporation (EOLIC), will start the first phase of the curlyleaf pondweed management strategy for the Iowa Great Lakes in April.