# Does dyeing the Chicago river green affect the fish? **URL:** \ **Category:** Factual Questions\ **Created:** [March 13, 2016, 5:27pm UTC](https://boards.straightdope.com/t/does-dyeing-the-chicago-river-green-affect-the-fish/748875 "2016-03-13T17:27:48Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![dalej42](https://avatars.discourse-cdn.com/v4/letter/d/67e7ee/32.png) [@dalej42](https://boards.straightdope.com/u/dalej42)\ **Post date:** [March 13, 2016, 5:27pm UTC](https://boards.straightdope.com/t/does-dyeing-the-chicago-river-green-affect-the-fish/748875/1 "2016-03-13T17:27:48Z")
The Chicago river was dyed green yesterday. Does the dyeing process dye the fish too? Any harm to the fish? ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [March 13, 2016, 5:43pm UTC](https://boards.straightdope.com/t/does-dyeing-the-chicago-river-green-affect-the-fish/748875/2 "2016-03-13T17:43:56Z")
Not supposed to be harmful. It’s a vegetable dye. Hydrologists use such dyes to trace the flow of streams and so on. ---
**Author:** ![Tim\_R.Mortiss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tim_r.mortiss/32/142_2.png) [@Tim\_R.Mortiss](https://boards.straightdope.com/u/Tim_R.Mortiss)\ **Post date:** [March 13, 2016, 8:22pm UTC](https://boards.straightdope.com/t/does-dyeing-the-chicago-river-green-affect-the-fish/748875/3 "2016-03-13T20:22:42Z")
That dye is probably the healthiest substance in that river. The fish probably see it like a breath of fresh air! ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [March 13, 2016, 11:02pm UTC](https://boards.straightdope.com/t/does-dyeing-the-chicago-river-green-affect-the-fish/748875/4 "2016-03-13T23:02:00Z")
St. Patrick’s Day isn’t until March 17. Aren’t they jumping the gun a bit here? ---
**Author:** ![dalej42](https://avatars.discourse-cdn.com/v4/letter/d/67e7ee/32.png) [@dalej42](https://boards.straightdope.com/u/dalej42)\ **Post date:** [March 13, 2016, 11:26pm UTC](https://boards.straightdope.com/t/does-dyeing-the-chicago-river-green-affect-the-fish/748875/5 "2016-03-13T23:26:58Z")
It’s the Saturday before St. Patrick’s Day. The unofficial end of winter. Huge Chicago celebration ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [March 14, 2016, 1:13am UTC](https://boards.straightdope.com/t/does-dyeing-the-chicago-river-green-affect-the-fish/748875/6 "2016-03-14T01:13:47Z")
The dye was actually used in the river first to [test for illegal sewage dumping into the river](http://www.chicagomag.com/Chicago-Magazine/March-2014/Ask-Chicago-How-Did-the-Tradition-of-Dyeing-the-Chicago-River-Green-Start/). Its decorative use came later. Also, we pretty much do St. Patrick’s Week here. ---
**Author:** ![jerry\_smissingfinger](https://avatars.discourse-cdn.com/v4/letter/j/e56c9b/32.png) [@jerry\_smissingfinger](https://boards.straightdope.com/u/jerry_smissingfinger)\ **Post date:** [March 14, 2016, 1:18am UTC](https://boards.straightdope.com/t/does-dyeing-the-chicago-river-green-affect-the-fish/748875/7 "2016-03-14T01:18:36Z")
> [@Tim\_R.Mortiss](#): > > That dye is probably the healthiest substance in that river. The fish probably see it like a breath of fresh air! That’s some funny shit there:D ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [March 14, 2016, 1:33am UTC](https://boards.straightdope.com/t/does-dyeing-the-chicago-river-green-affect-the-fish/748875/8 "2016-03-14T01:33:01Z")
> [@jerry\_smissingfinger](#): > > That’s some funny shit there:D Particularly given **WhyNot** ’s post just before yours… ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [March 14, 2016, 7:04pm UTC](https://boards.straightdope.com/t/does-dyeing-the-chicago-river-green-affect-the-fish/748875/9 "2016-03-14T19:04:15Z")
> [@WhyNot](#): > > The dye was actually used in the river first to [test for illegal sewage dumping into the river](http://www.chicagomag.com/Chicago-Magazine/March-2014/Ask-Chicago-How-Did-the-Tradition-of-Dyeing-the-Chicago-River-Green-Start/). Its decorative use came later. > > Also, we pretty much do St. Patrick’s Week here. Other sources confirm that story, and claim that they no longer use the same flourescein dye that was used then. From Wiki: > [@](#): > > The tradition of dyeing the river green arose by accident when plumbers used fluorescein dye to trace sources of illegal pollution discharges.[72] The dyeing of the river is still sponsored by the local plumbers union.[73] > > The United States Environmental Protection Agency (EPA) outlawed the use of fluorescein for this purpose, since it was shown to be harmful to the river.[72] The parade committee has since switched to a mix involving forty pounds of powdered vegetable dye.[74] Though the committee closely guards the exact formula, they insist that it has been tested and verified safe for the environment.[75] Furthermore, since the environmental organization Friends of the Chicago River believes the dye is probably not harmful, they do not oppose the practice.[76] ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [March 14, 2016, 7:53pm UTC](https://boards.straightdope.com/t/does-dyeing-the-chicago-river-green-affect-the-fish/748875/10 "2016-03-14T19:53:14Z")
[QUOTE=WhyNot] Also, we pretty much do St. Patrick’s Week here. [/QUOTE] Ah, sweet home Chicago. We used to call New Year’s Eve “Amateur Drinking Night” as the serious drinking happens in March. ---
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [March 14, 2016, 7:58pm UTC](https://boards.straightdope.com/t/does-dyeing-the-chicago-river-green-affect-the-fish/748875/11 "2016-03-14T19:58:16Z")
> [@Senegoid](#): > > St. Patrick’s Day isn’t until March 17. Aren’t they jumping the gun a bit here? It used to be that Chicago held the St. Patrick’s Day parade on the 17th (the river-dyeing happens on the same day). About 10-15 years ago, the city government decided that disrupting the city’s central business district with a parade (and much public drunkenness) on a weekday (when the 17th happens to fall on a weekday) wasn’t a good idea, and so, they moved the St. Patrick’s Day festivities to the weekend, on years when the 17th falls on a weekday. Similarly, the Columbus Day parade in Chicago was moved to the weekend – it’s celebrated as a day of Italian-American pride, but isn’t quite the drunk-fest that St. Pat’s is. ---
**Author:** ![Tim\_R.Mortiss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tim_r.mortiss/32/142_2.png) [@Tim\_R.Mortiss](https://boards.straightdope.com/u/Tim_R.Mortiss)\ **Post date:** [March 14, 2016, 8:06pm UTC](https://boards.straightdope.com/t/does-dyeing-the-chicago-river-green-affect-the-fish/748875/12 "2016-03-14T20:06:53Z")
I still expect to see Harrison Ford ducking in and out of that parade, trying to elude Tommy Lee Jones! ---
**Author:** ![AskNott](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asknott/32/5790_2.png) [@AskNott](https://boards.straightdope.com/u/AskNott)\ **Post date:** [March 15, 2016, 6:15pm UTC](https://boards.straightdope.com/t/does-dyeing-the-chicago-river-green-affect-the-fish/748875/13 "2016-03-15T18:15:53Z")
I don’t know about harmful, but the Cajun joint has a special on Blackened Greenfish.