Distribution Overview
Water hyacinth (Eichhornia crassipes) is established across the southeastern United States and California. It is most severe in Florida, Louisiana, and the Sacramento-San Joaquin Delta in California, where warm climates and nutrient-enriched waterways provide ideal conditions for year-round growth. In states with cold winters, water hyacinth may die back seasonally but reestablishes from seed banks or surviving plants in spring, maintaining persistent populations in regions as far north as Georgia, the Carolinas, and parts of Texas. Isolated occurrences have been reported elsewhere but are typically short-lived without human introduction.
Florida
Florida has the most extensive and historically significant water hyacinth infestations in the United States. The plant first established in Florida waterways following the 1884 New Orleans World's Fair, and by the early 20th century had become a statewide problem requiring organized management. Today, water hyacinth is present in virtually all of Florida's major river systems, lakes, and canals south of about latitude 30°N (which includes most of the state). The St. Johns River, Kissimmee River chain, Lake Okeechobee canals, and the Everglades Agricultural Area drainage system are all actively managed water hyacinth sites. Florida spends millions of dollars annually on water hyacinth control through the Florida Fish and Wildlife Conservation Commission's Invasive Plant Management Section. Despite decades of management, the species is not controlled — it is managed at acceptable levels in most managed areas through continuous treatment programs.
Gulf Coast States
Louisiana has extensive water hyacinth infestations throughout its bayou, marsh, and river systems, particularly in the Atchafalaya Basin, Calcasieu Lake, and numerous coastal waterways. Water hyacinth in Louisiana can become severe enough to impair navigation on important commercial waterways. Mississippi and Alabama have infestations in river backwaters and some lakes, though less extensive than Florida or Louisiana. Texas has water hyacinth in its eastern river systems (including the Sabine, Neches, and Trinity river drainages) and some reservoirs and irrigation canals. Texas populations are more seasonal than Florida populations due to occasional killing freezes.
Other Southeastern States
Georgia has water hyacinth occurrences in its southern river systems and some reservoirs, with populations expanding northward in recent decades. South Carolina and North Carolina have scattered populations, particularly in the Coastal Plain. These populations are less severe than Gulf Coast infestations and are managed more effectively due to greater susceptibility to winter cold-temperature events that set populations back each year.
California
California's water hyacinth problem is centered in the Sacramento-San Joaquin Delta — a complex network of channels, sloughs, and former marsh areas in the Central Valley that is critical to California's water supply infrastructure. Water hyacinth in the Delta blocks navigation, impairs water delivery, and creates major management challenges due to the slow-moving and complex waterway network. The Delta is the source of freshwater for much of Southern California through the State Water Project and the Central Valley Project, making hyacinth management a water supply security issue as well as an ecological one. California spends millions of dollars annually managing Delta water hyacinth. Outside the Delta, water hyacinth occurs in some Central Valley irrigation canals and scattered locations.
Factors Limiting Northern Range
Water hyacinth is limited northward by winter cold. Above-ground tissue is killed by temperatures below approximately -3°C (27°F). In states with cold winters, populations may be completely killed and only persist through the seed bank if seeds were produced before the freeze. Seeds require warm temperatures for germination and may not produce enough seedlings in cooler climates to maintain populations through multiple generations. This cold sensitivity is why water hyacinth management programs in northern states can sometimes achieve eradication of single-season occurrences, while Gulf Coast states face a permanent management challenge.
Reporting Sightings
Water hyacinth sightings outside its known range should be reported immediately to state and federal authorities. EDDMapS (eddmaps.org) is the national database for early detection and mapping of aquatic invasive plants. Contact your state department of natural resources for guidance on rapid response options if water hyacinth is found in a state or water body where it is not established. See also our regional distribution guides for more detail on each region.
References
- EDDMapS (2025). Early Detection & Distribution Mapping System. University of Georgia. eddmaps.org
- USDA NRCS PLANTS Database. Eichhornia crassipes. plants.usda.gov
- Tipping, P.W., et al. (2008). Water hyacinth and hydrilla management in Florida. Proceedings, Florida Lake Management Society.