55 ILCS 5/5-32034
No person obtaining contracts from the county and agreeing to be paid out of special assessments, has any claim or lien upon the county in any event, except from the collection of special assessments made or to be made for the work contracted for. However, the county shall cause collections and payments to be made with all reasonable diligence. If it appears that such an assessment cannot be levied or collected the county nevertheless, is not in any way liable to a contractor in case of failure to collect the assessment, but so far as it can legally do so, with all reasonable diligence, shall cause a valid assessment or assessments to be levied and collected to defray the cost of the work until all contractors are fully paid. Any contractor is entitled to the summary relief of mandamus or injunction to enforce the provisions of this Section.
The county treasurer shall keep a separate account of each special assessment warrant number, and of the moneys received thereunder.
55 ILCS 5/5-32034