Phosphorus helps grass germinate and grow, but excess phosphorus can be washed from a lawn by rainwater or sprinklers into lakes, rivers and streams.
It can then make waterways vulnerable to algae and weeds and deplete oxygen needed for native life.
Island Lake's proposal, which faces a village board vote Thursday night, comes four years after a Lake County Health Department report revealed high phosphorous levels contributed to the poor health of the town's namesake lake.
Among the lake's problems is the absence of a diverse or healthy plant community, the report said. There's also an overabundance of algae.
"We have had major algae and duckweed issues on our lake for years," said Ken Wick, leader of the village's lake management committee. "The last two years have been especially bad with the presence of blue-green algae, which can have adverse effects on people and pets."
Island Lake's ordinance would ban nearly all uses of liquid, solid or granular fertilizers that contain any amount of phosphorous. The ordinance would apply to treatments by property owners or commercial lawn care companies.
Natural or organic fertilizer containing naturally occurring phosphorous, such as yard waste or compost, would be exempt from the ban.
Fertilizer containing phosphorous would be allowed on flower beds, vegetable gardens and newly seeded or sodded areas. Farmers or agricultural companies could use it to grow crops, too.
Retail businesses that sell fertilizer would have to post signs explaining the village restricts the use of fertilizers containing phosphorous.
Violators would face fines ranging from $100 to $1,000 per offense.
Wick doesn't expect the restrictions, if approved, will result in immediate improvement on the lake.
"However, we should start to see less algae in years to come, as long as residents and landscapers abide by this new ordinance," he said. "It will definitely be a long-term thing."
If trustees approve the move, Island Lake would join Antioch, Gurnee, Libertyville, Lindenhurst and Mundelein among the suburbs restricting the use of fertilizers with phosphorous.
Illinois banned lawn care companies from using fertilizers with phosphorous on residential lawns in 2010. State law also limits the amount of phosphorous in cleaning agents, such as detergents.
Thursday's board meeting is scheduled for 7:30 p.m. at village hall, 3720 Greenleaf Ave.
Wick doesn't expect any public opposition.
"Its an easy ordinance proposal to defend," he said. "It's a no-brainer to help the environment and our namesake lake."