Tag Archives: Hood Canal Dissolved Oxygen Program

You, too, can observe oxygen changes in Hood Canal

I’m becoming something of a nerd when it comes to oxygen levels in southern Hood Canal. I’m sure it stems from the realization that we now have the technology to predict when fish will react to low-oxygen conditions by swimming to the surface, acting sluggish and sometimes dying.

Wolf eels at Sund Rocks in Hood Canal are disturbed by low-oxygen conditions.
Photo courtesy of Pat Lynch

In a story published in Monday’s Kitsap Sun, I took a step back from the immediate low-oxygen conditions and discussed our knowledge of Hood Canal, along with plans being formulated to address the low-oxygen problem.

Low-oxygen conditions reared their ugly head during the last week in September (Water Ways, Sept. 27). No major fish kills were reported before things began to improve somewhat by Friday (Water Ways, Sept. 30).

I’m keeping my eye on the charts and graphs and noticed a couple things that we can talk about. Compare the two oxygen profiles below with an eye to the surface conditions at Hoodsport (blue line) and deeper waters there below 40 meters.

Oxygen profile from Sept. 30
Oxygen profile today (Oct. 5)

The first thing I noticed was that the top of the hypoxic layer moved up from about 17 to 10 meters. That means if fish are avoiding that low-oxygen water, they will also move up. As far as I know, divers have not reported any observations to confirm or deny that change. One explanation is that the heavy ocean layer at the bottom is pushing up the entire water column. It also could mean that the surface layer has grown thinner, such as when south winds blow or north winds stop.

Meanwhile, the bottom of that middle hypoxic layer has moved up from about 70 to 50 meters and the edge has smoothed. That is an indication that the heavy ocean water, which contains more oxygen, is mixing with the bottom of the hypoxic layer.

One may also notice that the deep water at Twanoh (turquoise line) has become more oxygenated all the way through and is sharply higher in oxygen at the bottom. Perhaps this is an indication that the heavy ocean water has reached Twanoh and is mixing at the bottom, while winds and tides mix the water at the top.

University of Washington oceanographer Jan Newton has noticed a decline in the oxygen concentration in the middle layer at Hoodsport. She raises the prospect that this could result, in part, from low-oxygen water being pushed back from Lower Hood Canal by the annual intrusion of heavy ocean water. It needs to be checked further, she said.

I hope we get some diver observations this weekend or sooner. In discussing the current conditions with Dan Hannifious of Hood Canal Salmon Enhancement Group, we both wondered when deep-water fish will move back to their normal depth. What would it take for them to break through the middle low-oxygen layer to reach deeper water that is higher in oxygen.

If you would like to become an armchair observer of these conditions in Hood Canal, check out the graphs on the website of the Hood Canal Dissolved Oxygen Program. You’ll have to save old graphs to compare them closely, although another graph on the Nanoos website shows you changes in oxygen levels and other parameters over time for selected depths. (Click on “Regions” then “Puget Sound” and locate the Hoodsport buoy to find the graphs.)

Will the conditions in Hood Canal get better or worse this year? I’ll let you know, but if you see something unusual, feel free to post a comment here.

Oxygen levels improve in Hood Canal past few days

Fish and other sea creatures are finding some room to breathe in southern Hood Canal as higher oxygen levels have returned to the upper portion of the waterway after things looked pretty bleak on Monday. See Water Ways post.

I reported yesterday that fish could safely go down to 60 feet in a story posted on the Kitsap Sun website, but conditions are changing all the time. Now it looks like the cutoff depth is closer to 50 feet, while waters closer to the surface appear to be more oxygenated than yesterday.

I discussed the situation with Dan Hannifious of the Hood Canal Salmon Enhancement Group and included some of Dan’s comments in the story. Rather than repeat those comments here, I’ll let you click on the story.

What I did want to share are a couple graphs that show current conditions as of 9:30 this morning. Most of the real-time analysis comes from monitoring buoys in Hood Canal.

This is a profile of the oxygen levels from the surface down to the bottom of Hood Canal, or close to it. The blue line is for the Hoodsport buoy, turquoise for Twanoh and green for Dabob Bay. The black line is for Carr Inlet in South Puget Sound and purple is Point Wells near Edmonds. Biological "stress" occurs at less than 5 milligrams per liter, while "hypoxia" is shown at 2 mg/l. At Hoodsport, if fish go below about 18 meters, they will be in hypoxic conditions. Earlier this week, these condition were seen at the surface.
Data from the Hood Canal Dissolved Oxygen Program.
This graph shows changes over time. While conditions have gotten better near the surface (blue line), it doesn't show much change at 66 feet (green line). As we can see in the previous graph, the changes are occurring in shallower water and will take time to reach this depth. The red line shows the intrusion of heavy seawater containing more oxygen. When comparing, remember one graph uses meters, the other feet.
Data compiled by the Integrated Ocean Observing System

Hood Canal report finds septic systems a problem

An investigation into the causes of low-oxygen conditions in Hood Canal is coming to a close with this week’s release of a final report by the Hood Canal Dissolved Oxygen Program.

The pattern of fall oxygen levels show severely depleted waters from Twanoh State Park to Hoodsport with much better conditions to the north. (Click to enlarge.)
Map courtesy of Hood Canal Dissolved Oxygen Program

I described the report in general terms in a story published in yesterday’s Kitsap Sun. You may read the report for yourself at the HCDOP website.

What the five-year study learned about Hood Canal seems quite impressive. The full report contains extensive discussions about what causes oxygen to decline, the triggering mechanism for fish kills, the inputs of nitrogen that drive the system and much more.

One of the conclusions, which I focused on in my latest story, is that nitrogen from septic systems in Southern Hood Canal appears to be a pivotal factor in fish kills. When the natural decline in oxygen approaches a dangerous range, the added nitrogen from septic systems can tip the balance, causing excessive stress and sometimes death for marine creatures.

According to the report, one cannot easily separate the natural factors from the human factors that create problems in Hood Canal. The long, narrow fjord is flushed slowly compared to most marine systems. Organic carbon and nitrogen, which are the major players in oxygen decline, naturally come in from streams, groundwater and the Pacific Ocean. Numerous human sources, such as septic systems and fertilizers, must be taken into account.

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How do we address Hood Canal’s oxygen deficit?

Five years ago, a lot of people were wondering why fish were dying more often in southern Hood Canal during the fall.

Researchers knew that Hood Canal was sensitive to nitrogen. In other words, when nitrogen was introduced to the canal during summer months, nearly all of it was taken up by plankton, which grew into large blooms. When the plankton died, they sank to the bottom, where bacterial decay sucked up the available oxygen.

Beyond that, the questions were numerous: What were the most critical sources of nitrogen affecting the low-oxygen problem? What role does weather and water circulation play? And what can humans do to help the problem — or at least keep it from getting worse.

After a five-year, $4-million study, these questions can be answered with some certainty, as I point out in a story in Sunday’s Kitsap Sun. Now it is time for researchers to convey this information to political leaders and the public, as the Hood Canal Coordinating Council prepares a plan of action.

Scott Brewer, executive director of the HCCC, told me that the eventual plan is likely to include a suite of actions to address nitrogen inputs to the canal, particularly from human sources.
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Oxygen in Hood Canal reaches dangerous levels

I hate to be the voice of doom, but low-oxygen conditions in Hood Canal have never been worse — if you can believe the data gathered since the 1950s, alongside more intense monitoring the past several years.

In the southern portion of Hood Canal, you only need to go down about 30 feet to begin to see stressful oxygen levels in the range of 2 milligrams per liter. For current conditions at Hoodsport, go directly to the Hood Canal Dissolved Oxygen Program’s website, which lists data sent back from the Ocean Remote Chemical Analyzer (ORCA).

Sea creatures are beginning to show signs of stress, according to scuba diver Janna Nichols, who described her findings to me Wednesday after a dive in Hood Canal. She talked about fish “panting” as their gills moved in and out rapidly. Some fish, shrimp and other sealife had moved into shallower water. Watch Janna’s video of a wolf eel and other visuals she captured on the dive.

When low-oxygen conditions are that close to the surface, the danger is that a south wind will blow away the surface layer and bring low-oxygen water right to the surface, leaving fish with no place to go.

Of course, I have no desire to see a massive fish kill, but we already know that fish are probably dying in deep water due to the stressful conditions. I collect this information and offer these reports so that people can alert researchers when something happens. Being on the scene when fish are dying could provide important information about the nature of the low-oxygen problem. For details, please check out my stories in the Kitsap Sun Sept. 7 and Sept. 15 as well as the more technical report from Jan Newton on Sept. 7 (PDF 320 kb).

The phone number to report fish kills or oil spills is (800) 258-5990 or (800) OILS-911

If you haven’t heard, the worst low oxygen conditions normally occur in the fall after a summer of burgeoning numbers of plankton, encouraged by nitrogen and sunlight. By fall, much of the plankton has died and dropped to the bottom, where decay consumes the available of oxygen.

While there are plenty of natural sources of nitrogen in Hood Canal, computer models have demonstrated that human inputs from septic systems and stormwater can push things over the edge in the fall.

Officials are hoping that a new sewage-treatment plant in Belfair will begin to reduce the inputs of nitrogen into Lynch Cove. Another treatment plant is being planned in Potlatch. Stormwater upgrades also are being proposed for Belfair and other areas.

In addition to the low-oxygen problem, Hood Canal was closed to the harvest of oysters after people became sick from vibriosis, a natural bacteria that multiplies in warm conditions. See Kitsap Sun story Sept. 10 and Washington Department of Health maps.

The orange triangles represent this year's composite oxygen levels for the south half of Hood Canal. The latest reading, near the end of August, is the lowest ever seen.

Ocean conditions are playing tricks on Hood Canal

Hood Canal continues to baffle us humans with scenarios that we have never seen before, as I outline in a story in today’s Kitsap Sun. The canal’s latest failing is to forget that, by this time of year, there is supposed to be a layer of dense, oxygenated water lying on the bottom.

I’m being facetious, of course, about how the canal is “supposed to” behave. The fact that researchers are seeing something for the first time in Hood Canal does not mean it has never occurred before. And the fact that natural conditions can be highly variable does not mean that human inputs of nitrogen have no influence over the life or death of sea creatures.

As it has been explained to me, in years when natural conditions push Hood Canal close to the danger zone, human factors can push it over the edge. So limiting nitrogen flowing into the canal can make a real difference, especially in years when natural factors gang up to deplete the oxygen supply.

As I explained in some detail in today’s story, conditions in Hood Canal the past 18 months have been interesting to watch. Early in 2009, the average dissolved oxygen in the canal was near record highs, then the level dropped rapidly to measurements at or below what is normally seen in the fall. Over the winter, the levels never came back up — which is something never observed before. Now the levels are beginning to drop again, and we don’t know how low they will go.

What is encouraging about all the monitoring and studies conducted the past few years is that we can actually measure what is happening in real time, and we are in a better position to explain why the canal is responding as it does. Now if only we could predict the weather and ocean conditions, which seem to have a mind of their own …