march 30 field visit notes mill creekkg.docx

March 30, 2011 Field Visit Notes Mill Creek Fish Passage Assessment and Restoration Project, Phase 1

These notes give information that was shared on the field visit.

1) There is a Water Exchange Agreement between the Dept. of Water Resources, Department of Fish and Game, Los Molinos Mutual Water Company, and the Mill Creek Conservancy regarding water management. The MOU will be provided to the grantee once the project is initiated..

2) Lower Dam Site:

Issues at higher flows due to turbulence. Qualitative observations indicate fish are getting up the lower ladder but do not know if there are delays or injury to fish jumping at dam.

Sediment builds up in front of headgate and is routed into diversion ditch. Sediment is a recurring maintenance issue at fish screen.

Diversion season depends on water year; typically March 15 – October 15, however have irrigated as early as January in some years.

The toe of the dam structure is not being undercut; there is a pool at the bottom. A deep cutoff wall is constructed at the toe.

A preliminary screen assessment was conducted by CDFG in May 2010. With 24.38 ft/sec flowing thorough the fish screen the highest measured approach velocity was 0.43 ft/sec, sweeping velocity was negative at upper end of the screen, and ranged from .99 to 1.11 ft/sec range elsewhere.

Bypass is a 15” gate, opening of 1.1 ft., at 0.6 of a percent, does not extend all the way to water’s edge.

Chemistry of Mill Creek corrodes metal.

3) Cemetery Ditch Siphon The siphon became exposed in 1997. May be passage issue.

4) Upper Dam Site Screen placed approximately 1700’ down the ditch. Based upon the CDFG assessment in October 2010 the fish screen is adequately sized for diversion flows. The bypass discharges to the stream channel where there is insufficient channel depth. The drop is ~4 ft. into less than one foot of water at time of field trip.