Friday, December 14, 2012

Taking the Pulse of Our Watershed

By Tom Greco

Why is steam-flow monitoring important?

Pepperwood Steward Dennis Fujita, pictured above, has
been instrumental in the installation and development of
protocols for our steam-flow monitoring project

Water is the blood of life. Monitoring watersheds is extremely important because shifts in water availability and flow patterns can have drastic effects on our ability to produce food, support residential water usage and maintain fisheries. Some native species like the Coho Salmon are anadromous, meaning they dwell as adults in the ocean then ascend upstream into fresh water to lay eggs. 

Our seasonal streams serve as vital habitat for these and other threatened aquatic and riparian species.

Pepperwood is an excellent location for stream-flow research

Staff gauges being installed using a laser level earlier this year.
During the last storm event (early December), the water
reached up to the bottom of the gauge on the left, about
one meter above the bottom of the stream bed
Pepperwood’s undeveloped and protected 3,200 acres of wildlands represent a pristine slice of Bay Area ecosystem. The preserve is the headwaters of 3 different watersheds of the lower Russian River (Mark West Creek, Brooks Creek, and Franz Creek). This provides the ideal setting for a wide range of ecological research projects, including the investigation of natural water flow over and through different types of terrain. Rain falls on our section of the Mayacamas mountain range, refreshing springs and feeding our seasonal creeks before continuing down into the greater Laguna de Santa Rosa watershed, then on to the Pacific Ocean itself.

We monitor this water flow as it moves across the preserve to determine how water interacts with a natural, unaltered landscape. Our findings can help government and conservation organizations compare a pristine watershed with those under the influence of human imposed land alterations such as agricultural or residential development. Pepperwood’s Executive Director Lisa Micheli emphasizes that “by monitoring stream flow, we are taking the pulse of the watershed. The data we gather supports community water security efforts like the local Basin Advisory Panel." With this data providing a baseline, the impact of current and future development can be measured and weighed against the environmental costs.

Stream-flow monitoring methods at Pepperwood

Pressure transducer being placed in the stream bed
Pepperwood Steward Dennis Fujita spearheaded our monitoring project at Roger’s Creek, down in a canyon on the west side of the preserve. Equipment installed there includes a “pressure transducer”, which is placed at the bottom of the stream bed and measures pressure in pounds per square inch (this indicates water depth) and temperature. As the level of water increases in the stream, the pressure read by the transducer increases accordingly. Readings of stream depth are also taken manually from installed “staff gauges  which are located at two different points in the stream. These are fixed measuring sticks that provide staff and volunteers a quick and accurate way to record variations in stream depth and cross-reference with readings from the pressure transducer.

This pygmy flow meter is lowered into the stream at
different depths to measure water velocity
The third piece of equipment used is a “pygmy flow meter” on loan to Pepperwood from the Sonoma County Water Agency. This device is attached to a pole and lowered to different depths at chosen points across the stream. It has a component much like a water wheel that spins horizontally in the moving current and measures water velocity. Combined, the pressure transducer and pygmy flow meter produce enough data for us to determine the volume of water, or “discharge” passing through the Roger’s Creek stream during different seasonal events.

What is a watershed?

When rain falls on terrain, gravity dictates the path water takes from high points down to lower elevations. As it descends, it concentrates to form streams which in turn feed larger bodies of water. The Environmental Protection Agency (EPA) defines a watershed as “the area that drains to a common waterway, such as a stream, lake, estuary, wetland, aquifer, or even the ocean.” Watersheds can be defined in any range of scale, from a few acres of hills draining into a single creek to miles of landscape that supports water flow into a particular bay or ocean.

Pepperwood comprises the headwaters (the highest elevation lands in the watershed) of the Lower Russian River.

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