Concerns about toxic algae in Lake Erie are rising.

This year's algae bloom has stretched along the shores of Ontario, Ohio and Michigan and will be among the largest in recent years.

In Toledo, the city’s mayor has asked President Donald Trump for help from the federal government in cleaning up the lake and wants the U.S. Environmental Protection Agency to declare the western end impaired, which would allow for increased pollution regulations.

Mayor Paula Hicks-Hudson wrote in a letter sent to Trump last week, "As I look out my office at a green river, I can tell you one thing: the status quo is not working."

Scientists largely blame farm fertilizer runoff and municipal sewage overflows for feeding the algae growth. While there are a number of efforts to tackle the problem, it won't be solved for years.