Boise Fire Department and Ada County Highway District (ACHD) crews have contained what appeared to be a petroleum substance that was flowing from a storm water outfall along the Boise River near Americana and Shoreline in Boise. The substance in the river was reported to Boise Fire shortly after 12:30 this afternoon. Containment booms and pads on the river soaked up as much of the product as possible. At this point, Boise Fire and ACHD experts believe the amount of petroleum product that leaked into the river was not large. A relatively small amount can cause a visible sheen on the water. A sheen was visible on the water's surface for approximately one mile downstream to the area of N. 36th Street.
ACHD owns and operates most of the storm water system in Ada County and examined nearby storm drain access points in an effort to try prevent the substance from flowing into the river. ACHD was able to locate the substance flowing through the storm drain system at a manhole at Americana and River Street. However, while ACHD was investigating the next storm drain access point in the system, the source of the substance was determined to have stopped, so no removal of material from the storm drain was necessary at that time. An ACHD vacuum truck was ready to remove material in the event that it was still flowing through the system.
Finding the exact source of the substance will be difficult now that it has stopped. There are hundreds of points where it could have entered the system from city streets. The outflow where the substance was going into the river is fed from roadway grates in downtown Boise, the North End, and areas as far north as Hulls Gulch.
ACHD does not know exactly what the substance was at this point, other than it appears to be petroleum based.
It's important to note for safety and environmental health, something as simple as changing the oil in a car and putting it in the storm drain could cause a similar leak into the Boise River. Improper handling and disposal of potentially hazardous substances is a violation of local ordinances and state and federal laws and could result in criminal as well as civil penalties (fines).
ACHD will continue to investigate what happened and possible sources of the leak. At this point further clean up on the river itself appears to be unnecessary, and in fact, may be impossible. The fast river flows are predicted to quickly dilute any remaining product or expose it to evaporation.
Additional storm water information can be found on ACHD’s Web site at http://www.achd.ada.id.us/Departments/TechServices/Docs/Drainage/StW_You_brochure.pdf.