The hidden battle for our drinking water
Climate change is helping sea water invade land water
Buddy shares his research. He’s telling his half-brother, Teddy, this reservoir and embankment are in serious danger.
Sea level rise is attacking our water supplies - just as it’s attacking sewage and septic systems in many coastal counties [last week’s topic].
ABOVE AND BELOW THE EMBANKMENT
Storm surge Of course the most obvious threat is from storms. It seemed like a good idea at the time (the 19th century) to create a reservoir for Buddy’s and my hometown, Newport, by building an embankment around a seaside salt marsh. If the ocean had stayed where it’s been for centuries, that design would be okay. But in the 21st century, that ocean is rising, allowing a big storm to overtop or undermine the embankment more easily than in the past. When that happens, the reservoir will have to be drained, rebuilt, and refilled. Or abandoned.
That will be expensive; Newport can’t pay it from the current budget, so bond payments will stretch over several generations.
Newport Water already has the highest rates of any drinking water system in Rhode Island, and any further work requires permission from state regulators to raise them again. [Julia Forgue, director of utilities]
Not all towns will be able to find the money. (See our earlier letter.)
Intrusion The invisible way climate change is contaminating our reservoirs is by underground seepage from sea level rise. Engineers tell us:
Intrusion may gradually occur through groundwater pathways under the [reservoir’s] southern earthen embankment. [Newport Water Supply Report]
We’ll be able to watch the surge and waves sloshing salt water over the embankment during a storm, but we can’t watch that seawater slowly pushing its way underground into the reservoir during every high tide. The pressure of the ocean, just a few inches higher than in the past, can push salt water through the sand and soil which separates the ocean from a nearby pond or underground aquifer.
It’s not just Buddy’s and my city, of course. This invisible seepage is happening all up and down the coasts. In South Jersey, underground aquifers are becoming salty.
Saltwater intrusion will be exacerbated by both aquifer overpumping (reducing freshwater pressure from the land side) and sea-level advance (increasing saltwater pressure from the ocean side). Think of it as two pressure systems against each other, and the saltwater pressure is going to win since it is getting stronger while the freshwater pressure is getting weaker. [Ying Fan Reinfelder, Rutgers professor]
And it’s not just coastal reservoirs and aquifers that are threatened. Some cities pump their drinking water from a coastal river. Now that sea level rise is pushing more saltwater up that river, the point where salt and fresh meet is moving upstream. This means the riverbank locations where a city draws fresh water are becoming salty. Philadelphia is at risk from the ‘saltwater wedge’ moving up the Delaware River. Savannah is seeing the same thing in the Savanna River.
Salt water intrusion not only affects the water in our systems, it can rot the systems themselves.
Sea level rise can cause water level rises in coastal aquifers and even if the shallow groundwater remains fresh, the rising water would compromise subsurface infrastructure, such as pipes, cables, tunnels, foundations, and basements. If the rising water is brackish/salty, then corrosion problems could also be significant. [Michael Campana, American Water Resources Association]
Journalists can get good photos and stories from eroding dunes and collapsing coastal roads. Intrusion, however, isn’t something their readers can see, or maybe even imagine.
WHAT CAN WE DO?
As a community Education is likely the first need. A lot of municipalities are going to ask for a lot of money to keep their water supply safe from sea level rise, and more of us are going to vote for that big funding once we understand how the salt is getting there. If municipal leaders aren’t concerned or ready to take steps, their education should come first. We can lobby City Hall, form a Citizens Committee, and recruit knowledgeable residents to run for office. Buddy suggests we run for office ourselves! He’s a great door-to-door campaigner, and even if we don’t win, our campaign will have spotlighted this and other climate-change issues townwide.
What kinds of actions can a town take? Low cost ones involve a campaign to get residents and businesses to use less water. A higher water level in the reservoir pushes harder against intrusion.
The expensive solutions include new catchment areas for capturing and ponding rainwater, upgrading water filtration, treating and reusing wastewater, replacing leaky water mains, and acquiring distant water sources. Ocean desalination plants produce fresh water, yes, but they’re expensive and we need to have somewhere safe to put all the salt that’s filtered out.
As a family Much of our household activities, such as bathing, toilet flushing, showering with a friend, and some cooking can be done with slightly salty water.
To have more fresh water than our well or water utility provides, we can think about roof drainage into rain barrels (where legal), a replacement ground cover that doesn’t need much watering, or even a home desalination system ($700 - $5,000).
Buddy says saving water is just mental. He reminds me that, when we lived on a boat, we didn’t begrudge the need to use our water sources frugally.
Our readers certainly have additional ideas. Please send them to us, via Comments or by email.
READ, LEARN, ACT
Here’s a well-written story on Newport’s water supply in The Providence Journal.
A good overview of the problems.
And more than we want to know about storm surge.
The Delaware River’s salt front is pushing freshwater upstream.
Want to know which hometowns are endangered and which are more protected? Starting next week, Buddy and I will begin providing an array of measurements we can use to evaluate towns across America.
Buddy doesn't want us to claim credit, but today's 'Newport This Week' brings us the news that "Save the Bay has proposed creating protective dunes [below the ambankment mentioned above] in an effort to reduce coastal flooding spurred by rising sea levels."