!rowspan="2"|North Carolina<ref>Passeport E, Hunt WF, Line DE, Smith RA, Brown RA. Field Study of the Ability of Two Grassed Bioretention Cells to Reduce Storm-Water Runoff Pollution. J Irrig Drain Eng. 2009;135(4):505-510. doi:10.1061/(ASCE)IR.1943-4774.0000006.
!rowspan="2"|North Carolina<ref>Passeport E, Hunt WF, Line DE, Smith RA, Brown RA. Field Study of the Ability of Two Grassed Bioretention Cells to Reduce Storm-Water Runoff Pollution. J Irrig Drain Eng. 2009;135(4):505-510. doi:10.1061/(ASCE)IR.1943-4774.0000006.</ref>