Hi, I think I can help with this. The sheen is likely caused by iron-oxidizing bacteria, a type of bacteria that "feeds" by oxidizing ferrous iron (naturally present) into ferric iron. This process leaves rusty deposits as well as the oil like sheen you spotted. The way you distinguish between this and petroleum products is by swirling it. If it breaks up it's ferric iron, if it stays together, it may be petroleum.

I have been to the site with our storm water division and we did not see any contamination. The only film we located was organic in nature. Thanks for contacting us, users are our best way of finding issues in the parks and getting the right crews involved to make repairs.

This issue has been closed. If the problem persists, please re-open this issue and give us more detailed information on how to identify the location of the problem - then we will get right on it. Thanks a lot for reporting!