Let me make some observations about Hood CanalJuly 14th, 2008 by cdunagan
I had fun writing a piece for Sunday’s paper about the crazy and not-so-crazy ideas for fixing Hood Canal’s dissolved oxygen problem.
If you subscribe to the printed newspaper or buy it on the newsstand, you were able to see a giant graphic drawn by Jon Williams of our staff. I’m hoping that Jon can link his artwork to the online text in the next day or so. Meanwhile, you can view the text by itself on the Web site.
You may have heard some of these ideas before: digging a trench to North Bay, dredging out the raised “sill” that blocks flow, removing the Hood Canal bridge to increase mixing, skimming off algae with a boat, increasing natural algae-eaters such as clams and oysters, and pumping large amounts of air or oxygen into the water.
I also wrote a more serious story, pointing out unfinished work for the Hood Canal Dissolved Oxygen Program and questioning what kind of actions may be made and who will make them.
That story gathered a lot of comments, as Hood Canal stories generally do. I’d like to respond with several points of my own on issues that have been raised since the first story from June 30:
- Septic systems are listed high among the sources of nitrogen because they are not designed to remove nitrogen. It seems likely that some nitrogen will flow beyond a drainfield, but the percentage depends on things like type of soil, encounters with vegetation, uptake by organisms in surface water and denitrification of groundwater at the seawater interface.
- Other upland sources of nitrogen in developed areas, such as fertilizers and animal wastes, don’t seem to add up to the amount of loading measured for Hood Canal. Researchers admit, however, that they don’t have hard data to separate septic systems from the other sources.
- Septic systems tested for the HCDOP, as well as in other areas of the country, have led researchers to estimate an overall nitrogen loading of 50 percent of the original source material. That’s a broad average and could be significantly different for different systems and locations, since actual tests showed a range from 10 percent to 90 percent.
- It may be that older septic systems release more nitrogen than newer ones, but that assumption is based on the idea that older drainfields are smaller, more worn out and contain less area for denitrification. It’s also believed that brand new drainfields take a period of time to develop the right kind of bacteria to handle nitrogen at all. As far as I know, nobody can say whether proper maintenance will have any effect on nitrogen releases.
- The idea of requiring new systems to include mechanical equipment to remove nitrogen has some merit. Using that approach, all systems would eventually be able to remove nitrogen, but it would take many years. Maybe the focus should be on making sure waterfront homes are brought up to modern standards or else retrofitting waterfront homes with nitrogen-removal equipment, especially in Lower Hood Canal. Upland homes in North Kitsap and Jefferson County would seem to be the lowest priority, since they are farther from Hood Canal and the dead zone is at the south end.
- I’m puzzled by references to “leaking” septic systems, which is a term I’ve never heard in reference to nitrogen. Also, neither I nor the Kitsap Sun (corrected from previous version) editorial department has ever advocated the extensive use of nitrogen-removal equipment. I have written stories in which experts have called into question their use throughout the entire Hood Canal watershed. Check out a related editorial.
- None of the sewage treatment plants proposed in Lower Hood Canal would discharge their effluent back into the canal. Even if they did, the effluent would be very low in nitrogen, according to those who operate plants with biological membrane technology. Effluent from all four systems are proposed for upland disposal, thus returning relatively clean water to the aquifers or used to enhance low summer flows in the streams.
- A lot of the nitrogen is coming from the groundwater, but this was measured by the U.S. Geological Survey below the surface. Some researchers believe that a significant amount may be denitrified by bacteria at the interface where the groundwater flows into saltwater. Some point out that if the nitrogen were going deep into the ground, we would see higher levels of nitrogen in drinking water wells. Only a few places on the Kitsap Peninsula have been identified with nitrogen problems, and they don’t seem to be related septic systems.
- Hood Canal has more frequent low-oxygen events today than it did historically, according to the Hood Canal computer model. One can actually run the model using “pristine inputs,” meaning that the entire Hood Canal watershed is modeled like the least-developed and least-logged watersheds you can find today. Even in pristine conditions, Hood Canal will occasionally experience low-oxygen events — but nothing like we see today. The logical goal would be to remove as many sources of nitrogen as practical to reduce the frequency of low-oxygen events. Not everyone agrees what that means.
- Alders, another major source of nitrogen, can be removed, although I don’t think the idea is as simple as it sounds. Timber companies often spray special herbicides on newly planted areas where they want conifers to grow. This spraying has been criticized for its potential effects on the aquatic system and overall food web. An army of volunteers might be able to hand-cut alders to encourage conifer species. Meanwhile, logging operations also can cause damage to stream systems, as skidders dislodge soil and so on.
- Adding a bunch of artificial reefs in Hood Canal may have some merit, but it probably would not reduce the low-oxygen problem. In fact, one low-oxygen event apparently killed off a large percentage of the rockfish in lower Hood Canal. Sund Rock, a rocky outcropping, has never recovered.
- Mother Nature may not have designed Hood Canal very well, but the waterway does have some good qualities. Freshwater inputs are extensive, which creates a layering effect with freshwater floating on heavier seawater. Hood Canal has the right conditions for a natural set of Pacific oysters. The flavor of Hood Canal’s oysters — and their worldwide reputation — may be attributed to the kind of plankton grown in the waterway. There’s also the famous shrimp, crab and so on.
- Mother nature allows alders to grow first after a natural fire – or human logging. Alders produce nitrogen that feed the conifers that follow in succession. The problem is not alders but the extensive change in the landscape in a relatively short period of time. Natural events – including fire – cannot change the landscape the way humans do.
- The question about seals in Hood Canal has not been fully answered, but the population is probably not much greater today than in prehistoric times. Other wildlife has probably declined but may have been replaced with pets and livestock. I think it’s an interesting issue.
- Someone asked about the old dump for septic waste on the hill above Union. I have not written about this, but I probably should. Studies have shown that the groundwater and surface water drains away from Hood Canal.