William Bogot (right) of Highland Park and other volunteers plant a rain garden in a bioswale at Fink Park on May 11 during Friends of the Chicago River clean-up day. The contoured garden redirects polluted rain runoff. | Buzz Orr~Sun-Times Media

Steve Greenberg of Highland Park works on a rain garden at Fink Park during Friends of the Chicago River Day clean-up day May 11. The contoured garden redirects polluted rain runoff. | Buzz Orr~Sun-Times Media

Rain garden flowers and grasses were planted in a bioswale at Fink Park during Friends of the Chicago River clean-up day May 11. The bio-swale redirects polluted rain runoff. | Buzz Orr~Sun-Times Media

Environmentally-minded volunteers work on a rain garden and bio-swale May 11 at Larry Fink Park. The garden works to cleanse polluted rain runoff from an adjoining parking lot.| Buzz Orr~Sun-Times Media

Steve Black of Glencoe and his daughter Eleanor Black work with other volunteers on a rain garden and bio-swale at Fink Park in Highland Park May 11.| Buzz Orr~Sun-Times Media

Jonathan Rubenstein of Highland Park helps plant a rain garden that will cleanse polluted rain runoff from a parking lot during Friends of the Chicago River Day May 11. | Buzz Orr~Sun-Times Media