What we know about toxic chemicals reaching Puget Sound from rivers and stormwater

By Mindy Roberts, Environmental Engineer, Environmental Assessment Program

A lot of attention has focused on the amount of toxic chemicals reaching Puget Sound from surface runoff from stormwater and rivers that drain to the Sound.

So how much goes in?

Simple question, but not a simple answer

It’s a simple question with a surprisingly complex answer because the information available evolves over time.

Crime data analogy

Think of it like this: “How much crime is there in Washington?” A simple question – but how readily available is that information, and how will the answer be used?

• The first step is to find all available information on crime statistics at the state level to look at overall patterns and figure out what’s missing. You learn things from this initial pass. The information may answer some questions while raising even more. Inevitably, some parts of the state or particular crimes are underrepresented or not specific enough.
  
• The next step is to seek out the missing information by compiling new information from additional sources. You wouldn’t know what those gaps are until you finish the first phase. You focus your effort on the biggest gaps and the biggest areas of uncertainty. This leads to better information, but now you find out that some counties track crimes differently or more thoroughly than others.

Step by step, patterns do emerge

Where do you focus your resources? Each stage shapes your understanding of a complex topic like crime patterns based on the best available information. The first phase might indicate whether overall crime in the state is up or down, but those patterns don’t hold for all crimes or for all areas of the state.

A single value like “up 10 percent” may be accurate but doesn’t help if your job is to reduce violent crime in one county or report on car thefts in a particular city. We need information at all of these levels to decide where to put our collective resources to reduce the biggest risks.

Understanding toxic pollutants to Puget Sound crucial

We need to know the levels of toxic chemicals entering Puget Sound for many reasons. For instance:

• Are the levels a problem for humans or for fish?
  
• If so, what are the major sources to target with finite resources?
  
• What regions?
  
• What land uses?
  
• How much to reduce?

The first step is determining how much reaches Puget Sound or streams or lakes, but an even larger question we still must ask involves risk. What are the most important pollutants or crimes to control first and where should we focus our efforts? We could just reduce crime as a general statistic, but we need to prioritize -- what crime causes the most harm? First we need to know how much and what type of crimes are occurring.

Stepping stones for identifying toxic risks to Puget Sound

When Ecology, the Puget Sound Partnership, and others began asking the initial question “how much” several years ago, we did not have a readily available answer. In 2006, we began a project that includes not just toxic pollutants in surface runoff but also in fish and sediment, as well as human health concerns. The region could not wait five years for a final assessment, so we approached the toxics project in phases:

Phase 1: Initial estimates

Phase 1 provided us with initial toxics load estimates. We learned that when we add up the contributions from all chemicals and across all sources to Puget Sound, surface runoff (both river inputs and stormwater) is the dominant overall toxics source compared with other pathways (like wastewater and atmospheric deposition) and contributes millions of pounds per year. These other pathways may still be important for particular chemicals or areas. Phase 1 also identified areas where we needed more information.

Phase 2: Digging deeper into land-use contributions

Once we knew the importance of surface runoff, Phase 2 delved deeper and focused on what different land uses contribute. We learned that while surface runoff from forested lands represents the bulk of water reaching Puget Sound, residential land contributes disproportionately higher levels of pollutants including:

• Heavy metals like copper, lead and zinc
  
• Polychlorinated biphenyls (PCBs)
  
• Polycyclic aromatic hydrocarbon (PAHs)
  
• Plasticizers
  
• Herbicides
  
• Oil and grease

That’s a significant finding because it helps us focus our management resources on residential land-use activities. Surface runoff from commercial-industrial and agricultural lands also carries disproportionately high levels of some toxic chemicals. While the specific numbers evolved, Phase 2 still found that millions of pounds of toxic chemicals reach Puget Sound each year.

Phase 3: Finding out what’s in that surface water runoff

We designed Phase 3 to collect new water samples from surface runoff from these land use types to improve the data available. We selected representative areas of the Puyallup and Snohomish River basins and will finish monitoring in summer 2010. The findings will be released this fall – don’t be surprised when the load numbers change.

Dynamic studies equal changing numbers

So why do these numbers change? It’s because the information that becomes available improves over time. We don’t know what gaps to fill until we compile the known information. And sometimes the underlying patterns change as well. Will the information ever be perfect? No.

Take crime reporting. It, too, changes over time – as do underlying crime patterns. Crime-fighting tools are evolving right now to capture new patterns like the rise in identity theft and cyber crime so they can be managed effectively. It doesn’t mean that other crime-fighting tactics should cease.

Ecology and its partners develop tools to understand overall toxics patterns as the initial step in determining whether the levels of toxic chemicals are problematic. “The answer” could vary by chemical and by area within the Puget Sound region. And “the answer” will depend if you are a spawning salmon, a subsistence fisherman, or any of the millions of residents, human or other, in the Puget Sound region. The best available information evolves over time. It’s a necessary part of the transparent scientific process.

The numbers lead us toward a better strategy

Gathering good information on the amount of toxics pollutants entering our Puget Sound waterways is a great step in finding new and better ways to reduce toxics. We are taking the next steps right now to identify the biggest sources of these toxics and what harm they are doing to the things we care about. For some toxics, we already had enough information to take action, such as mercury and some flame retardants that build up in our bodies and environment, or copper from brake pads that harm salmon. With this additional information, we can continue to focus our efforts on controlling the sources of those toxics that contribute the most harm.

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