The Nutrification Study began in the year 2000. HCSEG hired Pat Trotter, a consultant, to help us design the study.  The Dewatto River was chosen for the study because there are few landowners on the river and the habitat is still quite good. 

For the last five years, summer interns have taken a habitat inventory and have gridded the entire system (walking every meter of stream). Using the initial data provided by the interns, helped us to choose eight tributaries to the Dewatto for the study.

The study consists of three test streams in the Dewatto System: Shoe Creek, Ralph Creek and Trib 8.  As in any study we must have streams to measure our success against. Therefore, there are also five control streams: White, Oak , Alder, Cutthroat and Huson.
 

Aerial view of the Dewatto River System.
 

Volunteers conduct a spawner survey on Shoe Creek.

When we initiated the study, we measured summer stream flow (pool & riffle surface area, etc.) to calculate the potential habitat available for juvenile coho.  Once we knew how many juvenile coho each stream could support, we calculated how many adult coho each stream would need to feed that number of juveniles.

With target numbers for each stream, we decided that the three test streams would receive 5x, 10x, or 30x the adult target numbers.  This decision was  based on what we understand about Wild Salmon ecosystems as a whole. 

We know that 137 species either directly or indirectly depend on Wild Salmon.  A direct relationship would be predatory.  For instance, an eagle eating a salmon.  Whereas an indirect relationship would be the rat eating the salmon carcass, and then the eagle eating the rat.   Since we know that other animals rely on carcasses,  we are trying  to determine what is necessary for balance in the ecosystem;  whereby the stream supports the ecosystem as a whole, as well as, produces healthy smolts.
 
In the Fall, we conduct spawner surveys.  We do this to determine how many adults escaped up the streams, and to keep track of where they were spawning.

When the Coho run has ended, we add carcasses to the 3 test streams.  Each stream receives its increases adult target number.  On average, we add about 1,500 -2000 Coho carcasses to our test streams.   We then survey these streams afterwards to see how many carcasses have disappeared each week due to water flow or scavengers.

Volunteers including Karen Lippy's students from North Mason High School help us to distribute salmon carcasses and spread them throughout the test streams.

As previously mentioned, we often see signs of nature at work, such as carcasses that have been  moved up onto the stream banks and other indicators of  bears, weasels, raccoons, hawks, eagles, etc. feeding on carcasses.  We also sample 6 fish from each stream for evidence of marine derived nutrients.

 In the Spring, we install smolt traps as part of our ongoing monitoring of the study.  We do this in partnership with technical assistance from Washington Department of Fish and Wildlife on all of our study streams.

 Matt Gillum, WDFW, helped us install smolt traps on our study streams.  This one is on Shoe Creek.

We are continuing to measure lengths & weights of coho smolts every year as well as measuring the cutthroat and steelhead we catch in the traps. This is a long term study that we hope will help answer the question:  How many Coho adults are needed to support a healthy ecosystem?

Check out our season smolt trap data.

We catch coho, cutthroat, & steelhead in the tribs of the Dewatto.

To find out more information on our smolt trap project, please click here.