What Water Quality Parameters Does EarthViews Measure?

Water Quality Data Collection

Often when we are setting up to go map an area people will pass buy and ask about the different sensors being used. When we bring up the fact that we are collecting water quality measurements in concert with each geolocated 360-degree panoramic image the next question is always, what are you measuring in the water? So here is an answer as it relates to the nearshore mapping we are doing in Puget Sound. 

Puget Sound Water Quality

Puget Sound is a fjord with a diverse bottom bathymetry. It also has a diverse nearshore, encompassing urbanized, sub-urban and more natural shorelines. This diversity is the result of the size of the waterway, making up nearly 1300 miles of shoreline. Because of its shape and size many areas create bottlenecks to seawater exchange from tidal influences. This can result in long long times for seawater to remain in certain areas exacerbating any negative impacts to water quality by people. Marne life in the Sound has evolved to be very specific with regards to habitat and water conditions. Degradation of these water quality parameters therefore can have lasting impacts.

  • One of the major concerns right now is acidification. pH of the water can decrease as a result of large amounts of carbon dioxide in the water. These levels have been decreasing because of climate change, destroying the calcium shells of baby oysters, clams and other shellfish, making it hard for them to reproduce. 
  • An equally problematic human induced water quality problem in Puget Sound is wastewater contamination from sewer overflows and leaky septic systems. The extra nutrient inputs from this contamination can cause harmful algal blooms which make shellfish poisonous. These blooms can also create eutrophication depleting certain areas of oxygenated water, creating “dead zones” where nothing can live. These zones have been seen at certain times of year in Hood Canal where tidal seawater exchange is slow. 
  • Toxic heavy metals are another source of severe impacts to water quality. These metals were, and still are introduced in urban industrial settings. Some of these areas have become SuperFund sites where hundreds of millions of dollars are spent to eliminate legacy pollution impacts.

Water Quality Fundamentals 

When measuring water quality scientists test three major categories: physical parameters like temperature, pH, and dissolved oxygen, biological parameters like bacteria levels and chemical levels like PCB’s. We focus on the following physical parameters: Temperature, pH, Dissolved Oxygen, and Salinity. Below is a table describing the specifications of the measurements collected by the instrument we use.  

Hana Water Quality Measurement Specifications

pH range0.00 to 14.00 pH
pH accuracy+ or – 0.02 pH
pH/mV input range+ or – 600.00mV
pH/mV input accuracy+ or – 0.5mV
ORP range+ or – 2,000.0mV
ORP accuracy+ or – 1.0mV
Dissolved oxygen range0.0 to 500.0% / 0.00 to 50.00mg/L
Dissolved oxygen accuracy0.0 to 300.0%, + or – 1.5% of reading or + or – 1.0% (whichever is greater)300.0 to 500.0%, + or – 3% of reading0.00 to 30.00mg/L, + or – 1.5% of reading or 0.10mg/L (whichever is greater)30.00mg/L to 50.00mg/L, + or – 3% of reading
Conductivity range0 to 200.0mS/cm (absolute EC up to 400mS/cm)
Conductivity accuracy+ or – 1% of reading or + or – μ/cm, whichever is greater
Resistivity range0 to 999,999Ωcm; 0 to 1,000.0kΩcm; 0 to 1.0000MΩcm
Resistivity resolutionDependent on resistivity reading
TDS range0 to 40,000mg/L or ppm (maximum value depends on TDS factor)
TDS accuracy+ or – 1% or + or – mg/L (ppm), whichever is greater
Salinity range0.00 to 70.00 PSU (Extended Practical Salinity Scale)
Salinity accuracy+ or – 2% of reading or 0.01 PSU, whichever is greater
Temperature range-5.00 to 55 degrees C/23 to 131 degrees F/268.15 to 328.15 degrees K
Battery type(4) 1.5V alkaline C cells, or (4) 1.2V rechargeable C cells
WeightMeter 750g/26.5oz.; Probe 750g/26.5oz.
Dimensions221 x 115 x 55mm/8.7 x 4.5 x 2.2 inches (H x W x D)

EarthViews Methods

We take surface level measurements which means they are taken at a meter or less depth. Most of the time surveying the nearshore we are in water that is shallow. Before each survey we calibrate the instrument to make sure the measurements are accurate. These measurements provide a good baseline of conditions and provide information that can be used to find areas that one would want to explore in more detail and with greater scientific rigor. 

Understanding Nearshore Matters

Water quality is directly related to the land water interface and improving Puget Sound water quality will require having the best possible understanding of what those nearshore conditions are like. This understanding is at the heart of our mission. 

Puget Sound Mapping Has Begun!

Mapping for the Puget Sound Nearshore project has begun. Click here to go to the Campaign. For the first leg of the journey we are mapping from West Point at the Discovery Park Lighthouse to Admiral Point in West Seattle. This is about a 10 mile stretch and encompasses a stretch of undeveloped shoreline at Discovery Park to the highly developed areas of the Seattle Waterfront and Port of Seattle. 

Why Start at West Point?

West point marks the northern extent of Elliott Bay, the bay adjacent to downtown Seattle. This area is also historically significant. West Point Lighthouse is an active aid to navigation to this day after being constructed in 1881. Fifteen years later what is now Discovery Park which includes the shoreline to the north and south of the lighthouse became Fort Lawton.

As we make our way along the Nearshore of Puget Sound also known as the Salish Sea we must remain aware that we are visitors to this place that has been home to the Salish Tribes of this region since the last ice age. For example, West Point has not always been called “West Point” – this is a name that has only been used for the past ~175 years. The original name for this place is PKa’dz Eltue (phonically: pa-uq-dz-al-tsu) meaning “thrust far out.” For thousands of years prior the Duwamish, Suquamish, Tulalip and Muckleshoot nations were active in this place; meeting, trading, sharing stories, gathering and preparing food (City ofSeattle).

The Developed Landscape

Since colonization the landscape of the Puget Sound Nearshore has changed dramatically and there is no better example of the extremity of these changes then the Seattle shoreline. As I paddle along the shore south of Discovery Park and into Elliott Bay Marina I encounter many harbor seals feeding. These marinas can become choke points for juvenile fish and salmon rearing along the nearshore. Because of the way some marinas are designed they can trap food sources for small fish, which in turn attracts bigger fish which brings in the harbor seals. It becomes its own little ecosystem, however this type of confinement is not part of a properly functioning Nearshore.

Perhaps no City in the United States underwent more landscape modifications during its development than the City of Seattle and those modifications are ever present in the Seattle Shorescape. When the City was being planned the shoreline area was a giant bluff, much like the bluffs of Discovery Park. In order to create a space for building a city center as well as a place for trading ships to dock these bluffs were graded. Known as the Denny Regrade this grading and leveling project removed millions of tons of soil which were then distributed throughout the nearshore area of Seattle. What is now the Seattle waterfront, the Stadium District south of downtown as well as Harbor Island which separates the Port of Seattle and Duwamish East and West Channels was all created by fill dirt from the re-grade. The area that was filled in was a giant estuary formed by the Green/Duwamish river. This estuary is now a tiny fraction of its original size and function. 

Big Wind

As I make my way along the Seattle Waterfront I observe the new Sea Wall that has been constructed with textured sections and concrete obtrusions meant to provide habitat for juvenile salmon. I wonder how effective they are. The wind picked up fiercely in the afternoon blowing me up the Ports East channel and putting an end to my first day of mapping. But what an adventure it was and how incredible it is to still see Harbor Seals and Great Blue Herons feeding among this industrial landscape. It gives me hope that there are solutions to recovering and conserving the Puget Sound.