Friday, November 6, 2009

How SARSAS Will Return Salmon to the Auburn Ravine, Part 2

Analysis of AR, Part 2----- WHAT WE KNOW

A. There is one barrier between highway 65 and Fowler road. The barrier is the Hemphill Dam located approximately two miles east of Lincoln along the north edge of Turkey Creek golf course. The dam is a flashboard dam with a formidable concrete apron plunging into a deep pool. We know the flashboard dam is taken down on or before October 15th. We know the dam creates a lake about four to five feet deep. This lake is approximately 150 feet wide and backs up a considerable distance. We know this dam differs considerably from all other flashboard dams along the Auburn Ravine in that the flashboard dam is not level with the downstream. The result is a considerable amount of silt above the dam. Silt is from bank to bank and backs up the length of the lake (a considerable distance) This portion of the Ravine would not support spawning. We know NID is looking at several alternatives regarding the future of the Hemphill dam. There is one pump serving the Hemphill dam and it will require screening.

B. The lake formed behind the dam would make an excellent holding pond for smolt. PCWA water temperature data show favorable year round water temperatures in this location. Further, the water is deep and protected from many predators. Also, there is ample shading of the waters in this area. Additionally, we know based upon water quality testing by the Lincoln Waste Water Treatment plant that conditions are quite favorable for trout, salmon and steelhead in this stretch of the Ravine.

C. SARSAS members have walked considerable lengths of the Auburn Ravine between Highway 193 and the Fowler Bridge. We know that silt in this section is minimal, cut banks are limited and spawning gravel is superior in quality. We have researched gravel needs by study online and this study supports our observation of the gravel along this section of the Auburn Ravine. Previous writings have reported a lower quality and quantity of spawning gravel than what we have learned in our direct observations of the stream bed. We now know that the potential for successful spawning of salmonids in this section of the Auburn Ravine is favorable. Further, this section has exceptional resting ponds with very favorable stream depth even in observed low water conditions typical of October flows.

D. We know there are beavers along this section of the Ravine, but there is an absence of the dams that are characteristic of the areas west of Highway 193.

E. Overall we are encouraged by this section of the Auburn Ravine for its ability to support spawning and rearing. This is far more encouraging than our knowledge in the past as we have done the observations and research to support what we now know versus some of the reports we read in the past.
We know this may require further studies and observation.

F. We will consider this area for spawning observation this year.

G. We know four salmon were observed in this section of the Ravine last year. Three salmon were observed in the pool below the Hemphill dam on December 8, 2008 by three fishermen. One salmon was reported below the Fowler Bridge in March of 2009. We know the salmon spotted at the Fowler Bridge was a salmon as experts observed this fish. The fish observed below the Hemphill dam were described as between six to ten pounds. These fish could have been salmon or steelhead.

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