Watersheds are basins where rainwater collects after storms, forming streams and river that exit into the sea. The San Juan Islands do not have rivers, but we do have many small watersheds that collect into seasonal streams and exit into ecologically sensitive bays and estuaries.

Restoring False Bay Watershed (PDF)


Rain that falls on the Islands flows to the Sea guided by the hills and valleys. These boundaries define watersheds, areas where all the rain drains to the same body of water. The largest watershed in the Islands is the False Bay Watershed, which drains San Juan Valley and Beaverton Valley into False Bay.  Along the way, this water picks up nutrients and chemicals from the watershed landscape and carries them to the shore.


Thinking in terms of watersheds transcends jurisdictional boundaries. The San Juan Islands are part of the Salish Sea which extends far up into Canada. The way we use our land on both sides of the border determines the health of this Sea.


Watersheds are not just about drainage. They also define ecological communities. The hills and mountains that border watersheds are also a barrier to creatures of all sizes, including birds. Over time, these communities change from their neighboring watersheds. The Salish Sea really is unique! Humans prefer to collect in watersheds, too. Look at the bigger map and compare with the locations of nearby cities.


All species depend on the flow of nutrients through their habitat. Watersheds collect nutrients from the soil, allowing stream life to grow and thrive. These nutrients then wash into the nearshore where they support the fantastic marine life that our Islands are famous for. However, extra nutrients from homes and farms can wash down watersheds and can harm wildlife by reducing the amount of oxygen in the water.


The San Juan Islands Conservation District takes the lead to study in great detail the levels of nutrients and many other chemicals in watersheds on each Island. Previous studies indicated some watersheds had high levels of nutrients, such as False Bay and Eastsound. We are currently monitoring these watersheds to develop trend data.


© San Juan Islands Conservation District 2016