Benthic barrier mats can be placed on the lake bottom to kill water plants by blocking their access to light during the growing season. Benthic barriers are most effective when used in small areas such as between docks or when a new population is found. Benthic barriers are represented by the darker area on image below.
They are being considered as one method for halting the spread of hydrilla since they are considered one of the safest and least detrimental.
Mats should be installed when plant growth is low -in early spring or in late summer after there's been a physical removal. They can be made and installed by professionals (~$15,000/acre) or homemade (An Insider's Guide to Benthic Barriers, NYSFOLA Diet for a Small Lake, Chapter 6, pg. 131). Commercial benthic barriers are made of plastic, fiberglass, nylon, or other non-toxic materials. Homemade barriers can be opaque garden tarps with PVC pipe frames constructed to hold them in place. l methods for controlling aquatic weeds. In addition to smoothing existing plants, they can prevent germination.
Unfortunately, their overall benefits are often counteracted by the difficulty in installation, difficult maintenance, and the high cost. Benthic mats need to be anchored securely so they are not a hazard. Zebra mussels can colonize the mats and sediment builds up meaning they must be removed at the end of each season.
NYSFOLA Diet for a Small Lake, Chapter 6: Aquatic Plants: Not Just Weeds, Benthic Barriers (pg. 129)
Last updated July 6, 2016