Abatement of the nuisance may in the discretion of the legislative body be performed by contract awarded by the legislative body on the basis of competitive bids let to the lowest responsible bidder pursuant to Sections 37903, 37904, 37905 and 37931 to 37935 inclusive of this code. In such event the contractor shall keep the account and submit the itemized written report for each separate parcel of land required by Section 39574.