Watershed

Watershed Definition: Precipitation that doesn’t sink into the ground or evaporate is surface water. This water becomes runoff, which flows into streams and eventually to the oceans to continue circulating in the hydrologic or water cycle. The entire land area that delivers water, sediment, and dissolved substances via small streams to a larger stream (or river), and ultimately to the sea is called a watershed, or a drainage basin. or … a watershed is: "that area of land, a bounded hydrologic system, within which all living things are inextricably linked by their common water course and where, as humans settled, simple logic demanded that they become part of a community." John Wesley Powell

 Divide marks the high point of land that separate one watershed from another.  Headwaters are the upper limits of the watershed.  Tributaries are smaller branches of watercourse that join together to make larger sections of the river.  Wetlands are permanently or seasonally inundated lands.  Channel is the normal area that the river occupies.  Floodplain is the area on either side of the watercourse that may be covered by water in times of high flow.  Confluence is where a branch of the watercourse joins the main channel.  Mouth marks the end of the watercourse at a body of water, usually a lake or the sea.  Groundwater exists in the spaces of bedrock or loose material, such as sand and gravel

All the water that enters a watershed always flows within that watershed. That means that what people put into the water, and how people use the water available to them, is very likely to affect the quality of the water—and its users—both locally and in other areas of the watershed. This is one of the reasons that there has been a movement to restructure land management and political jurisdictions to better reflect watersheds.

Some questions to ask when hiking in a watershed:  Where are the driest areas on the hillsides and in the canyons? Where are the wettest?  Are the trees and other plants different in these different areas?

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 Can you see examples of erosion – of water running off the surface and carrying dirt with it?  Why do we dig waterbars in our trails at ACR?  Are there any plants that indicate the presence of underground springs? Where on the preserve do you find these?  Can you see tributaries to the main streams (often dry) while you hike?  Where does the water at Martin Griffin Preserve flow? Where does this water come from?  How do people use streams? rivers? Ground water? (drinking water, other fresh-water needs, agriculture, industry, manufacturing, power, transportation, recreation)  How does wildlife use rivers? (food, habitat).

The Bolinas Lagoon Watershed includes MGP’s four creeks (Pike County Gulch, Garden Club Canyon Creek, Picher Canyon Creek (sometimes referred to as Audubon Canyon Creek), and Volunteer Canyon Creek (sometimes referred to as Weeks Gulch). Some highlights:  The largest creek entering Bolinas Lagoon is Pine Gulch Creek (watershed 7.8 square miles). It is ten time larger than the biggest creeks at ACR (Volunteer Canyon = 0.70 square miles, Pike County Gulch = 0.67 square miles).  Because of geological differences, Pine Gulch Creek carries about 10 times as much sediment into Bolinas Lagoon as all of the east shore creeks combined.  Tidal flow into and out of the lagoon is about eight times the total flow of all creeks combined (500 cfs vs. 4,000 cfs).

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 A full list of creeks that are part of the watershed are: Pine Gulch Creek, McCormick Creek, Copper Mine Gulch, Wilkins Gulch, Pike County Gulch, Garden Club Canyon Creek, Picher Canyon Creek, Volunteer Canyon Creek, Morse’s Gulch, McKinnan Gulch, Stinson Gulch

The Scrub Trail traverses Volunteer Canyon Creek at several places and provides an excellent opportunity to discuss watershed concepts with the kids. For a description of hike nuts and bolts, see the Watershed Hike Information excerpted from the School Program Overnight Docent Manual. There is a really good description of how to frame your hike, timing, etc.

It is clear from this old 1950s photograph that plate tectonics are intimately related to land forms and how water flows. Bolinas Lagoon is here because of the . Take a look at the Bolinas Lagoon, Olema Valley, and . You can clearly see the delineation of the Pacific Plate and the North American Plate. With Peninsula on the Pacific Plate moving northwest.

It is good to relate our little Volunteer Canyon Watershed to the Bolinas Lagoon Watershed to the larger California Watershed. An effective way to do this is to use California in the Palm of Your Hand.

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California in the Palm of Your Hand One can make a “map” of California’s watershed arena with only a pair of cupped hands, and thereby gain an understanding of the relationship of Sierra Mountain ranges and rivers to the San Francisco Bay.

With your hands together and slightly cupped, the fingers of the right hand form the San Joaquin Watershed with the tips of the fingers forming the mountains of Yosemite and Mount Whitney, and the rivers (Merced, Tuolumne, etc.) running between the fingers to the San Joaquin River where the fingers join.

The left hand forms the Sacramento River Watershed, with the Northern Sierra Mountains (Lassen, etc.) and the rivers (Pitt, Feather) flowing down to the Sacramento River. Mount Shasta (the left thumb) to the north, and the Condor Mountains at Bakersfield (right thumb) form the north-south boundaries of this handy map.

The Sacramento and the San Joaquin flow together where the hands meet, through the Central Valley (the palms) and out between the Coastal Range (heels of the hands) into San Francisco Bay and beyond.

(Adapted from Rasa Guistaitis, Reinhabiting a Separate Country: A Bioregional Anthology of Northern California, edited by Peter Berg and taken from Discovering on the Continent’s Edge, A Resource and Curriculum Guide to the , Point Bonita YMCA, 1986.)

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Map of California Water Resources

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Water Cycle: A Refresher (a picture is worth a thousand words!)

California Rain & Snow:  It rains and snows an average 193 million acre feet each year.  Of that, the sun drinks an average 121 million acre feet in evaporation & transpiration.  Of the 72 million acre feel left,  32% goes back into the ocean  31% goes into farming  29% goes to the environment  6% goes to cities & industry  2% runs off to Nevada

Or … on a planetary level … Water is 71-72% of Earth, Of that: Oceans 97.2% of total All Icecaps/Glaciers 2.0% Groundwater 0.62% Freshwater Lakes 0.009% Inland Seas / Salt Lakes 0.008% Atmosphere 0.001% All Rivers 0.0001%

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