An important update regarding COVID19:

Storm Water Pollution Prevention

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Storm Drains Are Only For Rain!

The storm drain system is comprised of gutters and storm drains which are designed to prevent flooding by moving rain water away from City streets and directly into local rivers (which flow to the ocean). Storm water pollution is occurring because rainwater and urban runoff (such as irrigation) picks up pollutants as it flows across paved surfaces and then carries them into the storm drain system. The water that enters this system is not ever treated or filtered and therefore any pollutants washed into the system flow with the water directly into the rivers and to the ocean. 

These pollutants contaminate our waterways, making them unsafe for people and wildlife. Toxic chemicals, polluted rivers and beaches, and trash accumulation in the ocean kills plants and animals, cost millions of dollars each year in clean up, and hurts the ability of our community to safely enjoy our environment by creating serious health risks. 

The City of Walnut is committed to the protection of our environment and water resources by reducing the impact of pollutants from urban runoff through implementation of its Storm Water Pollution Prevention Program as required by the National Pollutant Discharge Elimination System (NPDES) permit program. The NPDES permit program, as authorized by the Federal Clean Water Act, controls water pollution by regulating what is discharged into waters of the United States. 

Common sources of storm water pollution include litter, trash, pet waste, paint residue, organic material (yard waste), fertilizers, pesticides, sediments, construction debris, cooking grease, and illegally dumped motor oil and other harmful fluids. Many of these pollutants come from every day activities and can be easily reduced by using common sense and good housekeeping practices. Good housekeeping measures used to reduce storm water pollution are commonly referred to as Best Management Practices, or BMPs.

Certain activities, such as construction and renovation, may require a permit from the City of Walnut. Aspects of such permits may include BMP requirements to minimize water run-off and reduce the potential for storm water pollution.

For more information on which activities may require a permit, please contact:

Walnut City Hall
Building and Safety Department
21201 La Puente Rd.
Walnut, CA 91789
Ph: (909) 595-7543
Fax: (909) 595-6095

Even when a permit is not required for a particular activity, residents and businesses in Walnut are asked to follow BMP’s to reduce the potential for storm water pollution. This cooperation will help ensure the safety and enjoyment of our environment by keeping our storm drain systems clean and free from pollutants

Click on the activities listed below for storm water pollution prevention BMPS and other valuable information.

Auto Maintenance
Home Garden
Home Repair 
Kitchen (Fats, Oil & Grease)
Pet Waste
Used Motor Oil Recycling


Food and Restaurant
Used Motor Oil Recycling

Frequently Asked Questions

1. Are sewers and storm drains the same thing?

Sewers and storm drains are not the same thing. Sewers collect wastewater from indoor plumbing, such as toilets, sinks, washing machines, and floor drains. A municipal sewer system includes the collection, treatment, and disposal of sewage water. A municipal storm water system only transports water for flood control purposes; no treatment of storm water occurs before it is discharged to local water bodies.

2. How do I drain my swimming pool?

There two LA County Codes which define the legal method by which swimming pool or spa water may be disposed: Ord. 2007-0110 § 7 (part), 2007 & Ord. 99-0042 § 38 (part), 1999. Due to pollution and run-off concerns, the discharge any such water (including water from filter and pool equipment cleaning) into the street or storm drain system is generally prohibited.
The best way to drain swimming pool water is to drain pool water into the municipal sewer system (see question #1 for an explanation of this system). In-ground pools typically have a sanitary sewer drainage inlet near the pool equipment. Pools and spas that not plumbed with a sanitary sewer drainage inlet can be drained to a sanitary sewer line plumbed to the home. This applies to rinsing your pool filter as well. This may only be done if the water drains to a sewer system. Some people rinse the filter in their bathtub. Consult a licensed plumber or pool professional if you are unsure how to go about properly draining your pool. For further information, contact the City’s Building and Safety Department in City Hall at 909-595-7543.

3. How do I report a storm water pollution concern?

Concerns regarding possible pollutants being discharged to a street gutter, storm drain, or storm channel should be directed to the Building and Safety Department in City Hall at 909-595-7543. Additionally, the County of Los Angeles maintains a 24-hour toll free water pollution reporting hotline at 1-888-CLEANLA. To report serious spill emergencies (chemical, gas, etc), call 911.

4. If yard clippings and leaves are natural, why are they considered pollutants?

As yard clippings and leaves decompose, they deplete water of dissolved oxygen that aquatic species, including fish and turtles, need to survive. Excessive plant material also encourages algae growth. 
Additionally, contaminants such as dog waste, fertilizers, and oil from road dirt can adhere to these types of organic material. Therefore, when they wash into the storm drains, so do the contaminants.

For general storm water education information, please contact:
City of Walnut
Environmental Department
Ph: (909) 598-5605
Fax: (909) 598-2160




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