Living in the San Juan Islands, we are surrounded by the abundant waters of the Salish Sea, but freshwater is harder to come by. Even though we live in a rainy climate, the Olympic mountains cause rain shadows in the Islands that reduce our total yearly rainfall below that received in nearby counties. With small Islands we have small watersheds, which don’t collect water into large rivers. Our growing population consumes more groundwater than in the past, and salt water is starting to slowly intrude into the groundwater on Lopez. Water is one of our most important local issues!


Prehistoric Arrival

Water arrived on our planet when it was young, as giant snowballs from space that crashed to the surface and sent trillions of gallons of steam boiling through the atmosphere. When it finally cooled it turned to rain and collected on the surface. Most of this seeped into rocky crevasses and disappeared beneath the surface. When the planet had its fill, the water pooled on top and formed the oceans as we know them today. Indeed, there is more water inside the Earth than there is on top of it!

The Water Cycle Begins

Over billions of years the water dissolved the rocks around it and turned very salty and unfit for most organisms to drink. Luckily, we live close enough to our local star the Sun for it to warm up the oceans until the water, but not the salt, evaporates, sending freshwater on a long adventure. Just as luckily, we don’t live too close to the Sun like Mercury, where it is so hot that water only exists as steam.  On our planet the water eventually cools, for example when clouds are forced by wind up the chilly slopes of a mountain.

Now the water condenses, turning from gas back into a liquid, and falls to Earth as rain and soaks into the soil. The water that does not soak too deep flows downhill, collecting in streams and lakes. Eventually, all this flowing water returns to the lowest spot, the Ocean, where it mixes with the salty water and goes through the cycle all over again.

Fresh Water for Everyone

The water that sticks around longer has a chance to nourish plants, animals, and humans. Thirsty roots under the Island’s forests of Fir and Cedar trees absorb this water and send it up the trunk, where it keeps the wood alive and the leaves bright green. The water evaporates from millions of little holes in the leaves called stomata, returning to the atmosphere. In this way, forests keep freshwater cycling nearby and more available for all the life that depends on them.


Water that escapes the thick roots but doesn’t flow too fast downhill collects in underground lakes. Here in the Islands we can access these sources if we dig a hole down a few hundred feet, and can then pump the water back up for drinking. As long as the rain soaks into the ground fast enough to recharge the water we take from this lake, the cycle continues as usual. If we take too much, the water falls deeper underground and we have to dig deeper to find it. Also, ocean water surrounding our Islands mixes with the fresh water below the surface, turning it saltier. But as long as we take only what we need, the planet will do the rest for us!


© San Juan Islands Conservation District 2016