Weeds are increasing soil erosion. This damages vital streams that provide habitat for fish, including threatened and endangered species such as salmon. Weeds are increasing groundwater loss. Infested areas have higher water runoff and some weeds have a higher rate of evapotranspiration, which means that less water is stored in the ground and less water is available to wildlife. Weeds are blocking access to recreational sites.
Some noxious weeds are poisonous, producing irritating rashes after human contact.
Invasive plants do not respect property boundaries. Economic Costs are Great Weeds cost Western States hundreds of millions of dollars each year. A 1,300-acre ranch near Klamath Falls, Oregon, was recently abandoned due to infestations of leafy spurge. It later sold at auction for 10 percent of the value of surrounding property. The value of a weed infested ranch in North Dakota recently was reduced by 60 percent.