Feasibility of Fish Passage at Alameda Creek Diversion Dam

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Feasibility of Fish Passage at Alameda Creek Diversion DamAlameda Creek Watershed has been modified extensively for purposes of flood control and watersupply, and contains three major reservoirs (Calaveras, San Antonio, and Del Valle). The Lowerreaches of Alameda Creek near Fremont have been modified extensively for flood control and watersupply. Roughly 3,000,000 residents of the Bay Area rely on Alameda Creek for clean drinkingwater (SFEI, 2009). In addition to being managed for the growing urban area of Livermore, Dublin,Pleasanton, and Fremont, the watershed is managed for grazing, equestrian facilities, nurseries, and,more recently, vineyards.Alameda Creek Watershed is composed of three sub-watersheds (Figure 1-1; Table 2-1). The largestsub-watershed is the Arroyo de la Laguna Sub-Watershed, which at approximately 270,000 acresdrains more than 60 percent of the total watershed and contains the major reservoir, Lake Del Valle.The Arroyo de la Laguna Sub-Watershed would not be directly influenced by fish passage at ACDD.The Upper Alameda Creek Sub-Watershed is the second largest of the three sub-watersheds, which atapproximately 130,000 acres drains just less than 30 percent of Alameda Creek Watershed. TheUpper Alameda Creek Sub-Watershed contains the ACDD and ACDT, the subject of this fish passagetechnical memorandum, and it also contains Calaveras and San Antonio reservoirs (Figure 1-1).The Lower Alameda Creek Sub-Watershed is the smallest sub-watershed; it drains the lower area ofapproximately 40,000 acres, or 10 percent of the area of the entire Alameda Creek Watershed.2.2 UPPER ALAMEDA CREEK SUB-WATERSHEDThe ACDD and ACDT are located in the approximately 26,000-acre Upper Alameda Creek Basin,which is the second largest of five basins in the Upper Alameda Creek Sub-Watershed (Figure 1-1;Table 2-1). Alameda Creek is the main stream draining the Upper Alameda Creek Basin. Despitebeing the namesake of the entire Alameda Creek Watershed, this portion of Alameda Creek typicallydoes not have perennial flow, but rather is an intermittent stream that dries to a series of isolated poolsand sections of wetted channel during the dry season (Hagar and Paine, 2008).Wet season flows from the Upper Alameda Creek Basin are diverted via the ACDT to CalaverasReservoir, located at the confluence of Calaveras Creek and Arroyo Hondo basins. Calaveras Creek,an intermittent stream, drains the Calaveras Basin. It is the smallest basin in the sub-watershed,consisting of approximately 13,000 acres. Arroyo Hondo, a perennial stream, drains theapproximately 51,000-acre Arroyo Hondo Basin, the largest basin in the sub-watershed.The Upper Alameda Creek Sub-Watershed also contains the approximately 25,000-acre San AntonioBasin, which drains into San Antonio Reservoir, and the approximately 15,000-acre Mid-AlamedaCreek Basin, which is below both the Calaveras and San Antonio reservoirs (Figure 1-1; Table 2-1).2.3 STUDY AREAThe focus of this technical memorandum is to evaluate the feasibility and benefit of providing fishpassage at the ACDD (specifically steelhead, see Section 2.5). Though completion of habitat surveyson SFPUC and non-SFPUC properties above ACDD were not within this scope of work, of directrelevance to this technical memorandum are the streams and facilities that could be directlyinfluenced by fish passage at ACDD, all of which lie upstream of Alameda Creek’s confluence withCalaveras Creek, within the Upper Alameda Creek Basin.ACDD Passage June 2009 Page 2-2
2.0 SettingDuring the wet season, flows from the Upper Alameda Creek Basin are diverted to CalaverasReservoir from the ACDD via the ACDT (Figure 2-1), with peak flows passing over ACDD(Section 2.3.2).Calaveras Reservoir would not be directly affected by fish passage at ACDD, and is therefore notconsidered part of the study area for this technical memorandum. Features that could potentially bedirectly influenced by fish passage at ACDD are described in the following sections. These featuresare Alameda Creek upstream of the Calaveras Creek confluence (Section 2.3.1), a stream reach thatcontains potential barriers to future steelhead immigration (Little Yosemite) (Section 2.3.1.1), theACDT (Section 2.3.2.1), and the ACDD and its appurtenant works (Section 2.3.2.2).2.3.1 ALAMEDA CREEK UPSTREAM OF CALAVERAS CREEKThe portion of Alameda Creek above the confluence with Calaveras Creek is of direct relevance tothis technical memorandum, as this is the reach of the creek that could potentially be directlyinfluenced by fish passage at ACDD.Flows above ACDD are not impeded by major dams, and are best characterized as flashy, risingrapidly following precipitation events and then quickly subsiding once precipitation ceases(Figure 2-2). The portion of Alameda Creek above the confluence with Calaveras Creek typicallydoes not have perennial flow (SFPUC, 2007; Hagar and Paine, 2008), and conditions in the creek canvary dramatically depending on recent precipitation (Figure 2-3). Flows recorded at theU.S. Geological Survey (USGS) upper Alameda Creek gage (Gage Station 11172945; Figure 2-1)range from zero (periods when there is no measurable flow occur during most years) up to3,390 cubic feet per second (cfs), recorded on January 9, 1995 (USGS, 2009) 2 . Summertemperatures are higher and annual rainfall is somewhat lower than coastal streams draining directlyto the Pacific Ocean (Gunther et al., 2000).2.3.1.1 LITTLE YOSEMITEBetween ACDD and the confluence with Calaveras Creek, Alameda Creek flows through a reachknown as Little Yosemite, located approximately 2.6 miles downstream of ACDD and 0.2 mileupstream of Calaveras Creek (Figure 2-1). The Little Yosemite reach of Alameda Creek is a highgradient, approximately 0.2-mile-long section of stream channel with exposed bedrock and largeboulders that present potential impediments to fish immigration. These features consist of bouldercascades, turbulent cascades, and falls. The large boulders resting in the creek channel at LittleYosemite are likely the remains of a landslide mass that moved down the north canyon wall fromabout 600 feet above the creek (URS, 2009).In a separate study using a methodology modified from Powers and Orsborn (1985) (URS and HDR,2009b), two of these features, one 7.9-foot and one 9.5-foot waterfall, are identified as impassible toadult steelhead immigration in low to moderate flows (flows less than 100 cfs). However, in highflow conditions, which is when immigration would be expected, Little Yosemite may be passable.The ability of steelhead to pass Little Yosemite could be determined through surveys of futuresteelhead immigration. Little Yosemite and future steelhead immigration are further addressed inSection 6.1.2 The period of record for this gage is from October 1994 to the present (USGS, 2009).ACDD Passage June 2009 Page 2-3
Page 1: T E C H N I C A L M E M O R A N D U
Page 4 and 5: Feasibility of Fish Passage at Alam
Page 11 and 12: 1.0 Introduction1 INTRODUCTION1.1 B
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Page 20 and 21: (a)(b)Alameda Creek Diversion Dam (
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Feasibility of Fish Passage at Alam
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6.0 Additional Considerations and A
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9.0 Report Preparation9 REPORT PREP
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10.0 References10 REFERENCESAACE (A
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10.0 ReferencesHayes, Darrel, 2001.
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10.0 ReferencesSak, B., San Francis
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Feasibility of Fish Passage at Alameda Creek Diversion Dam

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