Background

The Utica Canal is considered an outstanding example of early water conveyance architecture and engineering, with some of its flumes hanging from the Stanislaus River canyon walls overlooking the river hundreds of feet below. It is a major contributor to the theme of water development in Calaveras County and as the principle surviving and active example of the Union Water Company System is listed on the National Register of Historic Places (NRHP).  On September 5, 2001 a wildfire known as the Darby Fire started south of Forest Meadows in the Stanislaus River Canyon. The fire quickly spread north east.  Among the structures in its path were five wooden flumes associated with the Utica Canal, major features of the Utica Hydroelectric Project (FERC Project No. 2019) and integral components of the water conveyance system.

The Utica Canal Serves as the only source of water supply for about 10,000 residents in the communities of Angels Camp, Vallacito, Douglas Flat and Murphys. Five of the six flumes (Flumes 9, 10, 11,13 and 15) totaling approximately 600 lineal feet were restored within two weeks fallowing the fire, replacing the structures in-kind with primarily wood materials. Reconstruction of these five shorter flumes was completed on September 30th.

A fifth and significantly more substantial flume in terms of its length and location in steep terrain, known as Flume 14 or ¾ Mile Flume, was destroyed in the fire and required site-specific engineering to properly support the structure. Flume 14 was also replaced in-kind, with changes limited to replacing wooden mud block footings with concrete near and below ground level, also incorporating steel into the higher trestle sections for structural adequacy and safety during the construction. In addition, scaling of the steep, rocky slope above the flume grade was necessary to prevent rock fall, provide safe conditions for workers and operating reliability once finished.

Temporary Restoration of Water Supply

As flumes9,10,11,13 and 15 were being reconstructed, UPA designed and constructed a temporary bypass around flume 14 consisting of two 10-inch diameter pipelines routed over a hill for approximately 3,000 lineal feet supplied by pumps drawing water from the Utica Canal. The temporary bypass was designed to supply 10 CFS (cubic feet per second), a flow adequate to meet only the most immediate water supply needs. Although the temporary bypass system began operating on October 1, 2001, approximately two weeks were required to replenish water storage reservoirs before critical restrictions could be lifted from residents.

Emergency Declaration and Compliance with CEQA