I. Habitat Description

The open waters habitat includes main river channels and portions of lakes, ponds, and backwaters that remain permanently flooded all year and appear less than 10% vegetated.  It also includes areas that are more than 10% vegetated with duckweed (Lemna, Spirodela, and Wolffia) and other nonrooted-floating aquatics. Because duckweed is free-floating, it can relocate day-to-day depending on current and wind direction. Therefore, any area of otherwise open water containing dense duckweed is classified as Open Water (rather than being placed into any of the vegetation-specific habitat classes). These habitats are subject to varying currents and wave action.

II. Sensitivity to Oil Spills

The open waters habitat is highly sensitive to oil spills.  Open waters provide critical habitat for many types of plants and animals, including a wide variety of fish, amphibians, reptiles, birds and mammals. Oil may inhibit the ability of vegetation to decompose, adversely affecting organisms within the detritus food web.  Oil removal in this habitat is often driven by the threat of migratory waterfowl and/or wetland animals becoming oiled. Light oils with high water-soluble fractions can result in acute mortality of submersed vegetation, fish, and invertebrates. Heavier oils tend to smother aquatic animals and plants, and coat shorelines.

III. Sensitivity to Response Methods

The following text describes potential adverse impacts to this habitat resulting from various oil spill response methods and provides recommendations to reduce impact when these methods are implemented.  This is not intended to preclude the use of any particular methods, but rather to aid responders in balancing the need to remove oil with the possible adverse effects of removal.  More detail about the response methods themselves can be found in the Inland Response Tactics Manual.