A hydraulic-permeation type environmental water-runoff filtration-system applicable to street curb-inlet type drainage-chambers, which generally cooperatively interconnect with street and parking-lot drains. The BLUEBAY-BMP™ pollution-trap provides advantage of community-tailored filtering stages, the preferred embodiment seting forth a convenient user-friendly prefabricated-kit assembly employing a basic build-in-place containment-housing which can be readily adapted to the studied needs of a given community,—without incuring alteration of existing sewer-stormdrains. The uniquely adaptative capability of the containment-housing enables selectively structuring multi-stages of filtration, which progressions address a variety of ecosystem-contaminants, ranging from basic street-refuse and floatable objects, to coarse sediment, finer silt, and comparatively minute albeit environmentally-hazardous petrochemicals, heavy-metals, phosphates, and nitrates;—all of which are readily retrieved from the apparatus confines via periodic maintenance for transfer to appropriate collection handling facilities.