Stormwater Drainage and Flash Floods

Did You Know…

Stormwater conveyance systems (curbs and gutters, catch basins, storm drain pipes, culverts, ditches, detention ponds, etc.) are typically designed to convey runoff from “every-day” or minor storm events and may overflow during larger storm events. It is reasonable to expect localized flooding during larger storm events including thunderstorms, micro-bursts, etc., that are common in the Northern Nevada high-desert environment.

Both Washoe County and private property owners play an important role in stormwater management and have separate stormwater maintenance responsibilities. Washoe County encourages its citizens to proactively identify stormwater facilities requiring attention and follow maintenance protocols.

Washoe County is responsible to maintain a functioning stormwater conveyance system located within County owned right-of-way and drainage easements accepted by Washoe County. Washoe County Community Services Department's Operations and Maintenance Division inspects and maintains both the open ditches and piped storm drainage collection systems along the 1,091 miles of Washoe County roadways. All other stormwater facility maintenance is the responsibility of either private property owners or a Home Owners Association (HOA).

Flash Flood Awareness

Washoe County has declared June 2016 as Flash Flood Awareness Month. Washoe County recognizes flash floods as an issue that our residents face each year and provides the following information in an effort to bring awareness to both the causes of flash flooding and recommendations for what residents can help do to prepare should you encounter a flash flood.

Washoe County owns and maintains a network of open ditches, culvert pipes and storm drain systems for the conveyance of stormwater, however these storm water facilities for the most part are only capable of conveying runoff which occurs as a result of the “every day” storm event.  Storm events that are capable of generating large quantities of storm water runoff will overwhelm the existing storm drainage systems, resulting in flooding and in some cases flash flooding.   All properties are subject to varying degrees of flash flooding severity.  Flash Flood Awareness month is an opportunity for individuals to focus on and assess the risk they may face from flooding or flash flooding and take appropriate steps to manage that risk.  Washoe County encourages all residents to evaluate their flood risks and take steps to mitigate property damage risk by purchasing of flood insurance and to protect themselves from personal injury or death by becoming informed and developing an emergency preparedness plan.     

For information on the basics of Floods (click here) and Flash Floods (click here)

For Preparedness Guide published by NOAA, please click here

Washoe County Emergency Management also has important preparedness information which can be found here

Photos and Videos of Recent Flash Flooding Events

Please view our 2013 presentation on Flash Flooding in Washoe County (1.8 MB PDF). This presentation was provided as part of a report to the Board of County Commissioners on September 24, 2013.

On June 10, 2013, a Washoe County employee caught a flash flood in Spanish Springs on video.

Property Owners Can Minimize Flood Risks

As a property owner and a resident of Washoe County, you can help ensure that drainage systems are clean and functional. If you observe a plugged drainage facility, notify the responsible entity in accordance with the guidance above. Plugged drainage facilities cause stormwater to overflow and may result in rerouting of stormwater and minor flooding. 

Things you can do include:

  • Visually inspect drainage facilities in your area and follow the drainage maintenance steps listed above to initiate cleaning of plugged drainage facilities. It is advisable to do this in the spring, fall and after any significant storm event.

  • Install properly designed improvements such as ditches, pipes, etc. to protect your property from localized flooding.

  • Call the Engineering, Capital Projects & Utility Division at (775) 328-2040 for assistance to determine if a permit is required for proposed improvements.

  • See Washoe County Development Code Article 420 (Division Four) for storm drainage standards.

  • Visit our Floodplain Management webpage to learn more about flood insurance and Washoe County's participation in the National Flood Insurance Program. The page includes a flood awareness brochure and links to other websites.

Grading Permits Are Required

See Washoe County Development Code Article 438 (Division Four) for grading requirements: 

  • A grading permit is required for any grading within a drainage facility including but not limited to a paved or unpaved swale, a paved or unpaved graded ditch, a gutter, a culvert, a trench drain, a catch basin, a drop inlet, a bio retention swale, a detention/retention basin, an infiltration basin, a dam, a pond, a wetland or a natural drainage.
  • No grading permit is required for grading that is proposed outside of a drainage facility or a special flood hazard area for grading of 50 cubic yards or less and 10,000 square feet of disturbance or less.

Washoe County Stormwater Maintenance Responsibilities

Washoe County is committed to providing reasonable and cost effective stormwater management and maintenance for our citizens. We continually review and improve the operation of our drainage facilities and our maintenance practices. Washoe County’s responsibilities include:

  • Cleaning and repair of stormwater facilities within Washoe County right-of-way or Washoe County maintained drainage easements.  For questions:
    • Call Engineering and Capital Projects at 328-2040 to determine roadway and easement ownership.
    • Call Operations and Maintenance at 328-2180 to request County-owned stormwater facility maintenance.

Private Property/Home Owners Association Stormwater Maintenance Responsibilities

Proper maintenance of stormwater drainage facilities is essential to provide continued operation of the stormwater conveyance system.  Weeds, sediment, garbage, grass clippings and other debris can negatively impact conveyance capacity often leading to localized flooding.  Maintenance includes the routine inspection and cleaning of ditches, storm drain inlets and pipes, driveway culverts, stormwater detention/retention ponds, and other drainage features.

  • Maintenance of drainage facilities located outside of County owned Right-of-Ways/easements are the responsibility of the property owner or a home owners association (HOA).  To determine the maintenance responsibility for a private drainage facility:

    • If you are a member of an HOA, review your CC&R’s, to determine if maintenance of private drainage facilities is a required activity of the HOA.  Contact Washoe County Recorder’s Office or review your mortgage closing documents for copies of CC&R’s. 
    • If drainage maintenance is not provided by an HOA, it is the property owner’s responsibility to clean and maintain those facilities.

Note:  There may be other situations not identified that need to be addressed on an individual basis.

Frequently Asked Questions

Who is responsible to maintain the drainage system within the right-of-way?

Washoe County CSD, Operations & Maintenance Division maintains the drainage system within Washoe County right-of-way. Contact the Division at (775) 328-2180. Private property owners or an HOA is responsible for maintenance of drainage systems within private right-of way.

My driveway culvert is crushed or damaged.  Who do I call to get the pipe repaired?

If the street is within a public right-of-way located in un-incorporated Washoe County, you may contact Washoe County CSD Operations & Maintenance Division at (775) 328-2180.

I have a natural drainage or man-made ditch running through my property and it needs to be cleaned. Whose responsibility is it to maintain my drainage?

Washoe County CSD Operations & Maintenance Division maintains drainage systems within drainage easements that have been accepted by Washoe County. Contact the Division at (775) 328-2180. Private property owners or an HOA is responsible for maintenance of drainage systems within private drainage easements or on private property.

I live on a roadway with roadside ditches, and I want to add a driveway. What do I need to do?

Call Washoe County CSD Engineering, Capital Projects & Utility Division at (775) 328-2040 for assistance. If the roadway is owned by Washoe County, a Street Excavation Permit will need to be obtained by your contractor who must be a County approved, licensed, and bonded contractor. Approval from an HOA may also be required.

I have a natural drainage running through my property and I want to fill it in. Can I do this, and if so, what do I need to do?

Call Washoe County CSD, Engineering at 328-2040 for assistance.  If the work will be allowed, a grading permit for grading in excess of 50 cubic yards and a special use permit for major grading activities will be required (see Article 438 for major grading criteria).  Other permits from the State or Army Corps of Engineers may be required under certain circumstances.