Stormwater Quantity

Stormwater staff investigate drainage and flooding concerns within the District's right-of-way, and design appropriate projects and solutions to accommodate and treat stormwater. They work closely with District Maintenance staff to implement drainage improvements. Stormwater staff are also the in-house resource to review drainage solutions proposed for development and capital projects. Flows to Waterways

Stormwater Quality

The Stormwater Quality staff helps the District meet Federal Clean Water Act requirements through implementation of the Stormwater Management Program. The Stormwater Management Program has many components including erosion and sediment control, monitoring, education and outreach, and mapping.

NPDES Permit

The Stormwater Quality staff oversees the Districts National Pollutant Discharge Elimination System (NPDES) permit program. A requirement of the Federal Clean Water Act, the NPDES program obligates cities like Boise with populations of more than 100,000 to address stormwater quality through implementing EPA-approved Storm Water Management Programs. The cities of Boise and Garden City, Boise State University, Idaho Transportation Department District 3, Drainage District #3, and ACHD are all covered under the Boise Municipal NPDES permit. In essence, the permit requires stormwater education, monitoring and treatment to reduce pollutants entering the Boise River. ACHD is involved in this program because it is the primary owner and operator of storm drainage systems associated with many of Ada County's roadways.

Stormwater Quality, How You Can Help:

Report Stormwater pollution problems to the Stormwater Pollution Hotline at 395-8888. Get as much information as possible such as the location and time of the incident, and any identifying characteristics of the vehicle involved (if applicable) so the problem can be responded to effectively.

Dumping substances into the storm drain systems is against the law. Unlike the water we use in our homes, stormwater does not go to a wastewater treatment plant.  Instead, stormwater flows directly to the Boise River or seeps into the groundwater.

Stormwater is water from rain or melting snow that does not immediately soak into the ground.  Instead, stormwater flows across hard surfaces such as concrete, asphalt pavement, or roofs and can pick up pollutants like lawn chemicals, automobile oil and grease, airborne dust and sediment, and pet waste.

The U.S. Department of Energy estimates that 80% of used oil generated by "do-it-yourself" (DIY) oil changes or 348 million gallons a year is disposed of in an improper manner. Improperly disposed used oil poses a significant threat to our waterways as it is often dumped or spilled into the storm drain system. 

You can avoid contributing to the problem by taking used motor oil, oil filters or antifreeze to the Ada County Landfill Household Hazardous Waste Collection Facility. The Ada County Household hazardous Waste Collection Facility located at the landfill at 10300 Seaman's Gulch Road, services all of Ada County.  They are open Fridays and Saturdays from 9am to 5 pm and are closed on holidays.  For more information call 853-1296. Solid waste collection companies such as BFI in Boise, Garden City, Eagle and Star, and SSC in Meridian will collect up to two gallons of used motor oil weekly per household.  J&M Sanitation in Kuna will collect up to five gallons of used oil weekly. Collect used oil in a clear plastic container and label it "used oil" then place the container on the curb on the same day as your trash/recycling collection.

If you can't make it to the landfill, there are also mobile collection units in Boise and Garden City.

Follow these other useful tips around your home, yard, and car to help prevent pollution.

At Your Home

  • Dispose of dirty carpet cleaning solution down a sink or indoor drain.
  • Clean latex paint supplies in a utility sink or bathtub, not in the street.
  • Dispose of animal waste by picking it up, bagging it and placing it into the garbage.
  • Use biodegradable soap when washing exterior walls and windows. Pour the excess wash water down a sink or toilet.

In Your Yard

  • Sweep driveway and sidewalk instead of hosing debris into the street or storm drain.  Collect debris and deposit it into the garbage.
  • Use less toxic ways to control weeds.  Hand-pull or dig weeds rather then using herbicides.
  • Wash tools and equipment over grass or soil covered area where wash water will not enter the street.
  • Empty pool or spa water into the sanitary sewer or determine when chlorine residual is zero and use for irrigation water.

With Your Car

  • Recycle used motor oil through the curbside recycling program.
  • Use a drain pan to catch automotive fluid when changing oil, antifreeze or other fluids.
  • Repair vehicle fluid leaks promptly.
  • Use sawdust, cat litter or other absorbent material to soak up automotive fluid drips or spills.  Sweep debris and throw into the garbage.
  • Drive your car onto landscaped surfaces for washing so the soap and water do not enter the storm drain system.
  • Use biodegradable soap to wash your car.  Pour the excess wash water down a sink or toilet.

For more information check out the Stormwater, the Boise River & You brochure.

Erosion & Sediment Control

It is the goal of the ACHD Construction Site Discharge Control (CSDC) program to minimize the effects of sediment, erosion, and construction debris on the Districts rights-of-way and storm drain systems. To reach these goals ACHD implements a CSDC Program Policy requiring the use of Best Management Practices (BMP) on all construction sites in the District's right-of-way. This policy requires CSDC Plans for projects.

Boise and Garden City also recently enacted Construction Site Erosion & Sediment Control Ordinances. As a result, your construction project may require an Erosion & Sediment Control Plan & Certified Responsible Person for plan implementation. For training class schedules and other information, refer to the following links:

ACHD is committed to providing information about appropriate (BMPs) for construction sites.  This is accomplished by maintaining a list of installers, suppliers, service providers and products of BMPs:

It is important that the District understand the limitations of products before they are recommended for a construction site.  ACHD is actively assessing new construction BMP products by requesting samples to be used as case studies for their usefulness in the county.  The information from this assessment is shared with the manufacturer and those involved with construction activities.  To inquire about the study or to participate, contact Luke Roberts at 208/387.6264 or

Sidewalk & Concrete Best Management Practices Program (BMP)

What are BMP's and why are they important?

Sidewalk and concrete best management practices (BMPs) are used to prevent or reduce the discharge of pollutants to stormwater from concrete work in the District right-of-way or private property. Having your crews implement BMPs such as washing out off-site, on-site washout in designated areas and training employees and subcontractors about how their work can impact water quality will lessen the amount of pollutants being introduced to the storm drain system. Protecting the storm drain system is important because most of the runoff that enters the storm drain system ends up in the Boise River or a tributary of the Boise River. Wastes entering the storm drain system are not routed to or treated by a waste water treatment plant.

Program Requirements and Enforcement

Sidewalk and concrete work BMPs shall be implemented by all bonded concrete contractors included in the hazardous sidewalk replacement program as well as others doing concrete work in the District right-of-way. Failure to implement and maintain appropriate BMPs while doing concrete work in the right-of-way or on private property adjacent to and affecting the right-of-way may result in enforcement action. This action may include, but is not limited to: clean up cost reimbursement, right-of-way permit revocation, shutting down the jobsite, and/or citations issued for violations of Boise City Stormwater ordinance. The District may attach the contractor's surety bond in order to facilitate any necessary clean up or to cover the cost of hiring a secondary contractor to complete the original work as assigned.

ACHD Ordinance 190: Section 3 Placing Debris on Public Right-of-Way

It shall be unlawful for any person to place, sweep, throw or track any dust, dirt, debris, refuse matter, or litter upon any public right-of-way; provided that in case of accident or necessity while properly using the public right-of-way such person shall not be liable if he or she shall immediately clean up the dust, dirt, debris, refuse matter, or litter caused thereby, and on his failure to do so the same may be done by the Ada County Highway District at his or her cost and expense, together with the costs of the action to recover the same.

Download Ordinance 190


ACHD has several monitoring projects underway to comply with NPDES permit requirements. The projects are designed to characterize the quality and quantity of pollutants discharged from the storm drain system. These projects include wet-weather monitoring of stormwater discharged to the Boise River during storms, sediment analyses, and floatable or litter monitoring of the storm drain system.


ACHD is in the process of field-verifying District drainage facilities such as pipes, outfalls and drop inlets. Collected field data is then mapped into a Geographic Information System (GIS) database. This is used to produce maps of drainage facilities and delineate storm-watersheds.

Illegal Dumping – Report a Problem

Storm drains are for transporting rain water from the streets to surface water or ground water. Dumping any pollutants to storm drains is illegal and a violation of the Clean Water Act. If you see someone dumping a substance down a storm drain, get as much information as possible, such as the location and time of the incident, and any identifying characteristics of the vehicle involved (if applicable) so the problem can be responded to effectively.
To report illegal dumping, call the stormwater pollution hotline at (208) 395-8888.
You can also report a non-emergency problem by sending an e-mail to  or call 387-6264.