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Stormwater FAQ

What is stormwater runoff?
Rain water that flows across the land is called stormwater runoff.  In vegetated areas such as forests, fields and wetlands, rain water seeps into the ground. However, when rain falls on paved and other hard surfaces it runs off and is conveyed by pipes and ditches directly to wetlands, streams, rivers, and Puget Sound.
Why is stormwater runoff a problem and why should I be concerned about it?
Stormwater runoff collects pollutants when it hits the ground, comes into contact with pollutants, and transports the pollutants to a waterbody. Many of our water pollution problems are due in large part to pollutants that are washed off the land by storms. When small amounts of pollutants from many sources are combined, they can cause big water quality problems.
Stormwater runoff increases the volume of water in streams because pavement surrounding the stream is impervious and does not allow rainwater to infiltrate into the soil.  As development occurs, an increase in stormwater runoff volume is generated.  Increased stormwater causes flooding, scours stream and river substrates, and impacts habitat.  Since less water infiltrates into the ground, there is less water available for stream base flows.
What are the types of pollutants commonly found in stormwater runoff?
Any substance that is not naturally in rain can be considered a pollutant; typical stormwater pollutants include:

Sediment: Excess sediment turns the water cloudy, making it less suitable for recreation, fish life, and plant growth.  When the sediment settles in the receiving water, it can smother trout and salmon eggs, destroy insect habitat (a food source for fish), and cover prime spawning areas.  Many other pollutants (oils, metals, toxic chemicals, bacteria) attach to the sediment.  This pollutant-laden sediment can settle and contaminate the receiving water body.  Exposed earth, construction, and dirt from equipment, vehicles and parking lots are sources for sediment.

Nutrients:  Nutrients such as phosphorus and nitrogen are needed by plants to grow, but high levels can be harmful to water quality. Excess nutrient levels can over-stimulate the growth of algae and other aquatic plants, resulting in unpleasant odors, unsightly surface scums, and lowered dissolved oxygen levels from plant decay. Lower dissolved oxygen levels kill fish.  Some forms of algae are also toxic to fish and other aquatic organisms, pets, and humans.  Fertilizers, animal wastes, detergents, road deicing salts, automobile emissions, and organic matter are all contributors to excessive nutrient levels in stormwater runoff.

Metals:  Many metals, including lead, copper, zinc and cadmium, are commonly found in urban runoff. Dissolved metals, in very low concentrations, can be toxic to aquatic organisms, interfere with their ability to respond to predators, and interfere with reproduction.  Metals can adhere to and contaminate sediments in water bodies.  Sources of metals in stormwater include vehicle use (copper from brakes and zinc from tires), galvanized metal (zinc from roofs, fences), pesticides, and paints. 

Oils and Greases:  Oil and grease are known to be toxic to aquatic organisms at relatively low concentrations; they can coat fish gills and prevent oxygen from entering the water.  Sources of oils and grease include vehicle use, streets and highways, parking lots, fueling areas, and equipment and machinery storage areas.

Chemical and Hazardous Substances:  Toxic compounds such as pesticides, cleaners, and paints are particularly dangerous in the aquatic environment and can be lethal to aquatic organisms. Excessive application of insecticides, herbicides, fungicides, and rodenticides, shortly before a storm, or application on impervious surfaces can result in the pesticide being carried to receiving waters. Cleaners, even those marked non-toxic and biodegradable, are toxic to aquatic organisms in very small quantities.  Many other toxic organic compounds can also affect receiving waters, including phenols, glycol ethers, esters, nitrosamines, and other nitrogen compounds. Common sources of these compounds include wood preservatives, antifreeze, and cleansers. 

Bacteria and other pathogens:  Fecal coliform bacteria in water may indicate the presence of pathogenic (disease-causing) bacteria and viruses. Pet wastes, wildlife wastes, leaking dumpsters, and improperly connected sanitation systems can all contribute fecal coliform bacteria.  Bacteria contamination can cause human illness, limit recreational use of a water body, and can lead to closures of shellfish harvesting areas and public swimming beaches.

pH:  Waters with very high (basic) or very low (acidic) pH are corrosive to metal surfaces and can cause biological problems for aquatic organisms and fish. There are several sources that can contribute to change of pH in runoff; these include acidic chemicals, cement used in concrete products and concrete pavement, and chemical cleaners.
What is the National Pollutant Discharge Elimination System (NPDES) Stormwater Program?
As required by the Clean Water Act, NPDES is a program that controls water pollution by regulating the discharge of pollutants through discharge permits.  The NPDES permitting program was expanded from the wastewater treatment and industrial process water discharges to include Stormwater discharges.  NPDES Stormwater Permits are issued to reduce pollutant discharges and require practices that will prevent pollutants from being washed-off by stormwater.  NPDES permits are issued by the Washington State Department of Ecology.  General Stormwater Permits include:  Municipal Stormwater General Permit, Industrial Stormwater General Permit, and Construction Stormwater General Permit.  Stormwater is also covered in the Boatyard General Permit.  For additional information on NPDES Permit requirements, please visit Tenant Information.

How do I know if I need a permit?
Federal regulations, 40 CFR Subpart 122.26(b)(14), lists types of industrial activities that must have a permit for the discharge of stormwater. The industries that are included are mostly identified by Standard Industrial Classifications, (SIC) or by a description of the industrial activity. The following links provide more information on facility categories needing permits and fact sheets associated with common industrial activities undertaken by seaport tenants.

Categories of Facilities that Need a Stormwater Permit
Sector P: Land Transportation and Warehousing Facilities (PDF)
Sector R: Ship and Boat Building and Repair Yards (PDF)
Sector Q: Water Transportation Facilities (PDF)
Sector U: Food and Kindred Products Facilities (PDF)
Additional information
What is an “illicit discharge?"
An illicit discharge is “…any discharge to the municipal separate stormwater system that is not comprised entirely of stormwater, except allowable discharges pursuant to an NPDES permit, including those resulting from fire fighting activities.” [40 CFR 122.26(b)(2)]. View the complete illicit discharge policy for the port.
What does the port consider an illicit stormwater discharge? 
Any non-stormwater discharge or dumping to the stormwater drainage system is considered an illicit discharge, including practices that allow pollutants to be washed off and carried by stormwater.  Examples include:
  • A measurable flow during dry weather that contains pollutants or pathogens
  • Disposal of vehicle maintenance fluids into a storm drain
  • Hosing or washing loading areas in the vicinity of storm drain inlets
  • Leaking dumpsters flowing into storm drain inlets
  • Old and damaged sanitary sewer line leaking fluids into a cracked storm sewer line.
How do I report an illicit discharge?
Observed spills or environmental hazards should be immediately reported to Port Management following the Seaport Environmental Incident Reporting guidelines. (89 KB, PDF)

Contact Ecology and the City of Seattle immediately if you observe a discharge that poses a severe threat to human health or the environment.
What are some control measures applicable in managing potential pollutants?
Prevent Erosion and Control Sediment by minimizing land disturbance and soil exposure, implementing erosion and sediment control plans, and sweeping sediments from impervious surfaces.
  • Cover and Contain pollutants that have the potential to be washed off. 
  • Wash Vehicles in a manner that prevents soaps and grit from washing off the pavement.  Even biodegradable and nontoxic soaps are toxic to aquatic organisms.
  • Reduce the use of pesticides and fertilizers.  Use sparingly, do not apply before or during rain, or to impervious surfaces.
  • Maintain vehicles to prevent oil drips and leaks.
  • Clean oil drips and spills before they are washed off by stormwater.
  • Store hazardous materials inside.
  • Pick up pet waste and dispose of it in a trash receptacle.
  • Keep dumpster covers closed.
  • Implement good housekeeping practices that help reduce and prevent hazardous wastes and chemicals from leaving the property.
  • Remember that any exposed pollutant has the potential to be washed away in stormwater.
What do I need to do for any construction activities on my property?
If your construction project disturbs more then 1 acre of land through clearing, grading, excavating, or stockpiling of fill material you are required to obtain a Construction Stormwater General Permit from the Department of Ecology.

Operators of new or previously unpermitted construction activities shall submit a complete and accurate permit application form called a Notice of Intent or NOI to the Department of Ecology. The NOI must be submitted 60 days prior to the time that any stormwater runoff discharges from a construction site.

For assistance in planning and designing your construction project, please contact the property manager for your site.