The state's Department of Boating and Waterways is extending its treatment of an invasive water weed in the Delta for an additional month.

The state will continue its herbicide treatments for water hyacinth in the Delta region, including parts of waterways in far East Contra Costa, through Nov. 30, agency spokeswoman Gloria Sandoval said this week.

The state started treating for the water hyacinth and Egeria Densa in mid-August and originally planned to stop in mid-October.

Water hyacinth, native to the Amazon region of South America, is a floating weed that can grow so densely that it covers the surface of the water, preventing boat access and clogging intake systems.

Contact Paul Burgarino at 925-779-7164. Follow him at Twitter.com/paulburgarino.