Invasives Watch

Welcome to InvasivesWatch.org
The website of the Great Raft Invasives Program

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Photo: Caddo Lake Institute

Program Information

The Great Raft Invasives Program (GRIP) is an effort to provide public information and education about giant salvinia and other invasive aquatic species in the lakes that were created by the historic log jam on the Red River known as the Great Raft, and in other lakes and streams connected to or affected by them. Because people who recreate, fish, or hunt in any one of these lakes may visit others -- with invasive species potentially hitchhiking on their boats and equipment –- a cooperative, coordinated effort is needed.

In addition to this website, GRIP will encourage Early Detection/Rapid Response actions; Shoreline Watch news alerts; and volunteer Weed Wardens to periodically report on lake conditions.

The Lakes

The six principal lakes in this area are Caddo and Lake O’ the Pines in Texas, and Cross, Wallace, Black Bayou, and Bistineau in Louisiana.

Except for Lake O’ the Pines, these are called “raft lakes” because they were created by the huge log jam on the Red River that persisted for hundreds of years before removal efforts by the U.S. Army Corps of Engineers in the 19th Century. Although naturally formed, the raft lakes are now maintained by spillways or dams. They still present to visitors a natural environment that is substantially similar to the world inhabited by the Caddo Indians before Anglo-Americans began arriving in the early 1800s.

Although Lake O’ the Pines is not a naturally formed lake – it was created by the damming of Big Cypress Bayou near Jefferson, Texas, completed in 1959 – it is included in the Great Raft Invasives Program because of its proximity to the raft lakes and its relationship to Caddo Lake.

Invasive aquatic plants and animals threatening any of the lakes of the Great Raft threaten all of these lakes. Their economic and recreational values are deeply intertwined. In particular, giant salvinia -- because it is a rootless, floating plant -- can easily move from one lake to another when boats and trailers are not thoroughly cleaned before relocating to another lake. A single fragment of giant salvinia can reproduce exponentially. Under conditions common to our area, giant salvinia infestations can double in size and mass in as little as one to two weeks.

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Photo: Caddo Lake Institute

Alligator weed, hydrilla, and water hyacinth are other non-native aquatic plants present in the lakes of the Great Raft area that can impair navigation, crowd out beneficial native plants, and spoil habitat for fish and other wildlife. Chinese tallow is an invasive wetlands tree that is rapidly displacing desirable native trees such as the mayhaw.

Through this website, the Great Raft Invasives Program offers a variety of useful tools and information to help residents and visitors to these lakes control invasives that are already present, and help prevent the arrival of potential new threats such as the zebra mussel and the Asian carp. The unique map tracking feature now in use on this site for Caddo and soon available to the other lakes will keep visitors to this website informed with up-to-the-minute information about lake conditions and where chemical and biological invasive plant control measures have taken place.

We hope you will enjoy this website and visit it on a regular basis to learn more and keep up with developments on the lakes of the Great Raft.

The Great Raft History

If you are interested in learning about the history of the Great Raft, please continue to this page.