There is no way around the simple and gut-wrenching truth about impacts on sealife from desalination plant intakes and outflows. Something is going to die. Actually, lots and lots of marine life are going to die.
If anyone has a realistic plan and one that mere financial mortals can afford, please put it on the table, quick. Many communities need to be in implementation phase like … now!
Santa Barbara is not alone. Coastal communities — everywhere this prolonged drought is drying out the land — are considering or already implementing the desal solution.
How big of a solution is this? Based upon my reading (one reference is, “Proposed Seawater Desalination Facilities in California” by Heather Cooley and Krinstina Donnelly of Pacific Institute in Oakland), if every single one of the proposed plants were built and operational, they may (no guarantees) be able to produce as much as 10% of our urban freshwater demand in California.
Is a 10 percent solution worth the cost, disruption of the seafloor and potential loss of marine life? The answer may depend upon how severe and prolonged the drought becomes.
When other sources dwindle, that 10 percent could become a bigger percentage without any extra gallons and then it does look more worth the price.
Besides the cost of the projects, people are considering some very serious and potentially deadly ecologic ramifications such as: How much sea life must die from the seawater intake and outflow systems? What does the intake pipeline look like and what options exist? What are we going to do with the salty brine?
My concern about the brine is that I want it massively diluted before it goes back in the ocean where it will affect sealife — both flora and fauna — which we care a great deal about.
That brine is harsh stuff and while marine life is able to adapt to chemical and salt content changes within natural and common fluctuations, a sudden powerful dose of desal brine may knock out marine life and create a dead zone near the release point.
The intake pipeline and terminus is something the designers can work with and try to design the best system possible in terms of achieving our water needs goals and our desire to have as small an impact on marine life as possible.
The pipeline itself can be a benefit to marine life in general and can add life to the sea by providing fabulous habitat where plants and critters can colonize and thrive.
My opinion is that the best way to maximize the benefits, to the point where they can, to some degree, outweigh the loss of marine life from the intake terminal, is to use manufactured “Sea Caves,” which can help us recolonize abalone and other desirable species.
Fish Reef Project is perfectly positioned to help make this happen, with funding from desal projects and donors.
The intake terminal itself is what sucks … literally. It sucks in great quantities of seawater and lots of life with it. That sucking impact is divided into two categories:
1. Entrainment, which means critters (like baby fish and other vitally-important low end of the food chain life forms) as well as plants and spores get sucked up against the intake filters and can’t escape. Survival prospects are grim.
2. Impingement, which means sealife gets sucked through the filters into the intake pipe and hence into the desal process, where survival prospects are far worse than grim. It is difficult to design and develop a filter that draws in sufficient quantities of water without creating entrainment and impingement problems.
Another option exists, called Sub-Surface Intake (SSI). The gist of the system is that the intakes are shallowly buried under the seafloor, and the natural sand or mud is used to filter the seawater. Thinking about it, it seems like it would indeed kill less overall sea life, although critters do live in the sand and mud.
I’ve heard of organizations like Santa Barbara Channelkeeper working to get municipalities to do studies to determine the effectiveness of SSIs in hopes we can develop desal plants and intakes that kill less marine life. I learned from Channelkeeper that some desal plant projects are already working on SSI concepts.
All-in-all, it strikes me that an SSI terminal at the end of a “Sea Cave” enhanced pipeline may be the best solution to mitigate the impacts of a desal intake and brine outflow on marine life. These would also make fabulous inshore fishing spots for kayakers and skiff fishers.
— Capt. David Bacon operates WaveWalker Charters and is president of SOFTIN Inc., a nonprofit organization providing seafaring opportunities for those in need. Visit softininc.blogspot.com to learn more about the organization and how you can help. Click here to read previous columns. The opinions expressed are his own.
