Stormwater and Lake Protection

Understanding the Stormwater Pathway to Seabreeze Lake

Discussions about Seabreeze Lake often focus on algae blooms, fish die-offs, phosphorus treatments, and water quality. Yet one of the most important questions may be much simpler:

How does stormwater move through the watershed, and what does it carry with it?

Understanding that pathway is essential when evaluating potential sources of nutrients and pollutants entering Seabreeze Lake.

This article focuses exclusively on stormwater movement, organic material storage, rainfall infiltration, leachate generation, and nutrient transport.

Stormwater Always Follows Gravity

Stormwater is simply rainwater that falls on the landscape and moves downhill.

Along the way it can pick up:

• Sediment

• Organic matter

• Nutrients

• Fertilizers

• Animal waste

• Decaying vegetation

• Other pollutants

The amount transported depends on:

• Rainfall intensity

• Duration of rainfall

• Soil conditions

• Slope

• Vegetation cover

• Distance to waterways

The greater the rainfall event, the greater the potential for transport.

The Chipper Site and Organic Material Storage

For many years, Surfside has maintained a location near Seabreeze Lake where tree debris is collected, chipped, stored, and later distributed.

Organic materials commonly stored at such sites include:

• Branches

• Limbs

• Leaves

• Needles

• Bark

• Wood chips

• Other vegetative debris

Organic material naturally decomposes over time.

As decomposition occurs, nutrients contained within the material begin to break down and become mobile.

What Is Leachate?

When rainfall or irrigation water moves through a pile of decomposing organic material, it can dissolve nutrients and organic compounds.

The resulting liquid is commonly referred to as leachate.

Leachate can contain:

• Phosphorus

• Nitrogen

• Dissolved organic carbon

• Organic acids

• Suspended solids

• Other decomposition byproducts

The concentration depends on the age of the material, moisture content, storage duration, and rainfall intensity.

The important point is that water moving through organic debris does not necessarily emerge with the same chemistry it had when it entered.

Rainfall Infiltration and Water Movement

Under normal conditions, some rainfall infiltrates into the soil.

Vegetation and tree roots increase infiltration and slow runoff.

However, during prolonged rainfall events, soils may become saturated.

When this occurs:

• More water flows across the surface.

• More water moves through organic piles.

• More nutrients can be mobilized.

• More runoff reaches nearby waterways.

The closer a storage area is to a lake or canal, the shorter the pathway stormwater must travel before entering the waterbody.

Atmospheric Rivers Change the Equation

The Pacific Northwest is increasingly experiencing powerful Atmospheric River events.

These storms can deliver large amounts of rainfall over short periods.

Atmospheric River events classified as AR4 and AR5 are often associated with:

• Intense rainfall

• Flooding

• Elevated runoff

• Increased nutrient transport

Under these conditions, stormwater pathways become far more active.

Areas that may generate little runoff during ordinary weather can become significant sources of water movement during major storms.

Nutrient Transport During Major Storms

Nutrients do not move by themselves.

They move with water.

During Atmospheric River events, stormwater can transport nutrients from many sources simultaneously, including:

• Residential properties

• Fertilized landscapes

• Septic-system influenced areas

• Roadside surfaces

• Organic debris piles

• Shoreline areas

• Exposed soils

As runoff volumes increase, so does the potential for nutrient transport.

The larger the storm, the greater the volume of water moving through the watershed.

Seabreeze Lake as a Collection Point

Seabreeze Lake functions as a receiving waterbody.

Stormwater entering the surrounding watershed eventually converges toward the lake.

This means nutrients and organic matter from multiple sources can accumulate within the system.

The lake effectively becomes a collection point where watershed inputs are concentrated.

For this reason, watershed management is often considered just as important as lake management.

The Outfall Connection to the Pacific Ocean

Seabreeze Lake is not isolated.

Water leaves the lake through an outlet and ultimately reaches the Pacific Ocean.

This creates a direct hydrologic connection between the watershed and coastal waters.

During major storms:

• Lake levels rise.

• Outflows increase.

• Water moves more rapidly through the system.

• Nutrients and suspended materials can be transported downstream.

Residents have observed substantial flows moving through the outlet channel during major Atmospheric River events.

The pathway is straightforward:

Rainfall → Watershed → Seabreeze Lake → Outfall → Pacific Ocean

Why Riparian Vegetation Matters

Riparian vegetation serves as a natural treatment system.

Trees and vegetation along shorelines:

• Slow runoff.

• Increase infiltration.

• Absorb nutrients.

• Stabilize soils.

• Filter sediment.

• Reduce erosion.

Healthy buffers reduce the amount of material reaching waterways in the first place.

When buffers are reduced or vegetation is removed, more stormwater can move directly into lakes and canals.

Looking at the Entire Watershed

When evaluating water quality, it is important to focus not only on what is happening inside the lake, but also on what is happening throughout the watershed.

Questions worth considering include:

• Where does stormwater originate?

• What materials does it encounter?

• How much runoff is generated during major storms?

• What natural filters exist between runoff sources and the lake?

• Are those filters being maintained, reduced, or expanded?

These questions are particularly important as Pacific County experiences increasing rainfall intensity associated with climate change and Atmospheric River events.

Protecting the Watershed Protects the Lake

The most effective lake-protection strategies often begin outside the lake itself.

Reducing nutrient transport at the source is generally easier and less expensive than treating nutrients after they have entered a waterbody.

Whether the source is stormwater runoff, organic material storage, shoreline disturbance, or other nutrient pathways, understanding how water moves through the watershed is essential.

Seabreeze Lake, its outlet, and the Pacific Ocean are connected by that movement of water.

Protecting the watershed helps protect the lake.

Protecting the lake helps protect the ocean.

And protecting both begins with understanding the path that stormwater takes from the landscape to the water.