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Stormwater FAQ

Stormwater FAQ: What is the Marine Stormwater Utility?

In 2014, the Port of Seattle formed the Marine Stormwater Utility (Utility) under the authority of several sections of the Washington State RCW and other statutes that authorize port districts to provide services, facilities, systems, and programs for surface water and stormwater management and pollution control. The Marine Stormwater Utility serves properties in the City of Seattle and King County, providing additional water quality protection for the Puget Sound.

The Utility is responsible for collecting and administering drainage fees related to the stormwater system on Port Maritime properties, including those managed by The Northwest Seaport Alliance (Alliance). The revenue collected from Port and Alliance managed properties, including from tenants, is directed to assessing, repairing, and upgrading the Port’s aging stormwater system. The system includes drain lines, catch-basins, manholes, and other structures that convey stormwater from Port properties into receiving waters such as Salmon and Elliott Bays, the Duwamish Waterway, and Puget Sound.

With the formation of the Port’s Utility, we are able to increase investments to maintain and manage the stormwater system on Port properties. This in turn will help the Port achieve its environmental goals and support property managers and tenants in compliance with stormwater permit conditions, including the Phase I Permit, Industrial Stormwater General Permit, Boatyard Permit, and other federal, state, and local stormwater regulations.

Stormwater FAQ: What is NPDES?

The National Pollutant Discharge Elimination System (NPDES) is a program that controls water pollution by regulating the discharge of pollutants through discharge permits. The federal law that defines it is the Clean Water Act, and Washington State implements the program consistent with Water Pollution Control Law Chapter 90.48 RCW.

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 prevent pollutants from being washed-off the land 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, Boatyard General Permit, and Construction Stormwater General Permit. For additional information on NPDES Permit requirements, please visit Washington Department of Ecology.

Stormwater FAQ: 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.”

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

Report illicit discharges on Maritime Port property to 24-hour dispatch: (206) 787-3350

Stormwater FAQ: What are controls for managing water pollution?

Prevent pollutants from entering stormwater by implementing best management practices (BMPs). Some examples of BMPs include:

  • Cover and contain pollutants that have the potential to be washed off the land
  • Wash vehicles in a manner that prevents soaps and grit from entering drains or streams; 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 the land by stormwater
  • Store hazardous materials inside
  • Pick up pet waste and dispose of it in a trash receptacles
  • 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

Within the City of Seattle, specific BMPs must be followed. These are outlined in the City's Stormwater Manual.

Stormwater FAQ: What are stormwater pollutants?

Any substance that is not naturally in rain can be considered a pollutant. Typical stormwater pollutants include:

Sediment in excess turns the water cloudy, making it less suitable for recreation, aquatic 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 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, 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 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 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 affect receiving waters, including phenols, glycol ethers, esters, nitrosamines, and other nitrogen compounds. Common sources of these compounds include wood preservatives, antifreeze, and cleaners.

Bacteria and other pathogens, such as fecal coliform bacteria, 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 lead to closures of shellfish harvesting areas and public swimming beaches.

pH is a measure of water and can be neutral, very high (basic), or very low (acidic). High or low pH in water can release metals or other contaminants into the environment and cause biological problems for aquatic organisms and fish. Several sources can contribute to change of pH in runoff, including acidic chemicals, cement used in concrete products and concrete pavement, and chemical cleaners.

Stormwater FAQ: What is stormwater runoff & why do I need to be concerned?

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 eventually Puget Sound.

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.

Pavement surrounding a stream is impervious and does not allow rainwater to infiltrate the soil, which increases the volume of stormwater runoff. As development occurs, more 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.

Stormwater FAQ: What do I need to know for construction stormwater?

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. The City of Seattle has additional requirements for construction activities: City of Seattle Stormwater Code

Operators of new or previously unpermitted construction activities shall submit a complete and accurate permit application form to Washington Department of Ecology called a Notice of Intent (NOI). 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.

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