FISH PASSAGE CENTER 847 NE 19 th Avenue, #250, Portland, OR Phone: (503) Fax: (503) us at

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FISH PASSAGE CENTER 847 NE 19 th Avenue, #250, Portland, OR 97232 Phone: (503) 833-3900 Fax: (503) 232-1259 www.fpc.org/ e-mail us at fpcstaff@fpc.org MEMORANDUM TO: FROM: FPAC David A.

1 FISH PASSAGE CENTER 847 NE 19 th Avenue, #250, Portland, OR Phone: (503) Fax: (503) us at MEMORANDUM TO: FROM: FPAC David A. Benner DATE: October 8, 2014 RE: Rock Island Fishway Update On September 24, 2014, the Fish Passage Center inspected the Rock Island Dam Adult fishways. The drawdown of the Wanapum reservoir coupled with very low September river flows have created a difficult situation for adult fish passage at Rock Island Dam. This memorandum will provide an update of the effort that fishway personnel at Chelan County PUD have been conducting over the last several weeks to pass adult fish beyond Rock Island Dam. Over the month of September, river flows have decreased dramatically at Rock Island relative to flows recorded in August. Over August, the average outflow from Grand Coulee was approximately 127 Kcfs as Grand Coulee was drafting for summer flow augmentation and as part of the Lake Roosevelt Incremental Storage Release Program. In September, drafts from Grand Coulee ended. The project began to refill to an elevation near 1283 feet by the end of September for the Kokanee spawning operation. Outflows from Grand Coulee averaged approximately 63 Kcfs over the month of September. Under the current tailrace elevations, due to the Wanapum drawdown and at river flows roughly less than 75 Kcfs at Rock Island, Chelan PUD cannot operate their powerhouses. Because daily average river flows have been below 75 Kcfs, Chelan has been forced to spill for some period of the day (typically 45 Kcfs), and operate the powerhouse for another portion of the day. There have been several days over the last month when flows have been too low to operate the Rock Island powerhouse at any point during the day (see the highlighted yellow in the flow table below). Under spill only conditions, most attraction is to the middle (spillway) fishway, which is not outfitted with a denil; and the tailrace water level is generally below the sill of the fishway, creating a small waterfall condition. Under spill only conditions throughout an entire day, adult passage at Rock Island Dam has generally been poor (see table below). g:\staff\document\2014 documents\2014 files\ docx

2 The following table displays Rock Island Dam information over the month of September and during early October. The table displays daily average powerhouse and spillway flows along with total salmonid and lamprey passage over each day. Power Generation Flow (Kcfs) Rock Island Project Data Total Spill Salmonid (Kcfs) passage Lamprey Passage 9/1/ /2/ /3/ /4/ /5/ /6/ /7/ /8/ /9/ /10/ /11/ /12/ /13/ /14/ /15/ /16/ /17/ /18/ /19/ /20/ /21/ /22/ /23/ /24/ /25/ /26/ /27/ /28/ /29/ /30/ /1/ /2/ /3/ /4/ /5/ /6/

3 From the above table, it is clear that during days when flows are predominantly passed via the spillway (days that are shaded yellow), salmonid passage numbers have decreased sometimes quite dramatically relative to days with higher powerhouse operation. Over the dates of September 12, 13, 14 and 18, adult salmonid passage was minimal at Rock Island. During these dates the project was either spilling all day or operating with a very high proportion of spill, with little or no powerhouse operation. It should be pointed out that on September 30, 2014, Rock Island was forced to spill all day with no powerhouse operation however total salmonid counts did not drop as much as the dates in mid- September. From mid-september, the counts of coho salmon have been increasing at Rock Island and were outnumbering Chinook on September 30, On September 30, 2014 (a day with all spill), counts of Chinook decreased over 80% relative to the previous day; whereas, coho counts on September 30, 2014, dropped about 50% relative to the previous day. It is possible that coho are better able to find and pass the denils when there is no powerhouse operation as compared to Chinook. It is difficult to determine the impact of all spill days on the passage of lamprey as daily counts have generally been low (between zero and sixteen per day). During the four days that the powerhouse did not operate over September and early October, there were no counts of lamprey. However, over this period there were multiple other days with no counts of lamprey. Additionally on September 12, 2014, the powerhouse operated only minimally with predominantly spill, a condition that cause salmonid counts to decrease drastically from the previous day. However lamprey counts were the second highest of the September and early October period. The following picture displays the main spillway entrance. Under the current low tailwater conditions and during spill operations, fishway attraction water drops several feet into the tailrace. 3

4 When the powerhouse is operating at Rock Island, the tailwater is typically higher making the middle fishway entrance more useable. However, due to low tailwater conditions, the lower portion of the middle fishway does not have a suitable amount of water for adequate passage up the first weirs. To pass fish that enter the middle fishway, Chelan PUD s fishway attendants have been closing the main entrance hourly to allow the water level to rise to the point where passage conditions are more suitable over the first several weirs. The middle fishway at Rock Island also has a side entrance that on the date of inspection was inaccessible due to low tailwater elevations (see picture below). Chelan PUD has completed an operation to cut the concrete and basalt between the side entrance and a small channel on the right side of the picture (completed approximately October 3, 2014). The completion of this channel has provided an additional entrance at the middle fishway. However, the passage over the lower weirs remains an issue that will require entrance gates to be opened and closed to allow water levels in the lower fishway to rise to provide adequate passage. 4

5 The right bank fishway at Rock Island typically passes the majority of adult fish (70% 80%). Two denils are installed at the right bank fishway: one at the tailrace entrance (TRE) and another at the left powerhouse entrance (LPE). When the second powerhouse is operated, the right fishway is quite effective in passing adult salmonids. During the hours of the day that the second powerhouse is operating, not only are the denils at the TRE and LPE entrances operational, but Chelan PUD has been operating the two RPE entrances. The following pictures show the two right bank entrances with denils during their operation on September 24, The first picture shows the LPE entrance with denil operational and the second shows the TRE entrance with operational denil. Although both denils are operational at the right bank, Chelan PUD has been also utilizing the two RPE entrances. 5

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7 The use of the RPE entrances has required Chelan PUD to open/close the RPE entrances on an hourly basis. With the entrances open and with the tailrace low, there is not sufficient water below the first weir moving up the fish ladder, creating a several foot drop in water from the first weir. As such, Chelan closes the RPE entrances and allows the lower fishway water surface to increase, creating better passage over the first weir (see pictures). This operation seems very worthwhile. On September 24, 2014; during two cycles of opening/closing of RPE 1&2, at least five hundred salmonids entered the RPEs and moved through the lower ladder. When the powerhouse is operating, the denil entrances are functional (LPE and TRE) as well as the two RPE entrances that are opened hourly to allow fish in and are then closed to provide better passage conditions up the ladder. The first picture below shows the RPE entrances open. The second picture shows the first ladder weir when the RPE entrances are open. And the last picture shows the first ladder weir with RPEs closed. 7

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9 All in all, despite the low flows that Chelan PUD has been receiving along with the drawdown of the Wanapum pool and associated Rock Island tailrace, fishway attendants/biologists at Chelan PUD have been working very hard at creating favorable fish passage conditions at Rock island Dam. This has involved large daily changes in river conditions from all spill to powerhouse operations, each of which influences fishways in various ways. Chelan PUD has worked hard to provide a pulse of water daily in which the powerhouse can be operated which has provided the best possible conditions for migrating adult salmonids. Over most days of the week, Chelan PUD has been able to operate the powerhouse beginning at 8:00 9:00 AM; however over some weekend days, the powerhouse has not begun to operate until later in the afternoon (3:00 4:00 PM). To provide the best possible conditions for passage, it is recommended that the powerhouse attempt to operate similar to what has been occurring weekdays, with the powerhouse operating through much of the daylight hours. To increase passage during spill operations, Chelan has completed a small channel through concrete and basalt to open up a second entrance at the middle fishway. To further improve adult passage under powerhouse operations, Chelan PUD fishway attendants have been locking fish through the entrances and up the ladders at the middle (spillway) fishway and RPE 1&2 which requires manually opening and closing entrances hourly. Upon visiting Rock Island Dam on September 24, 2014, it was clear that passage of adults past the dam has been a complicated and difficult situation with the minimal river flows in September and early October. Over the last several days river flows at Rock Island have been suitable for Chelan PUD to operate their powerhouse beginning at 8:00 9:00 AM and continuing through most of the day. It is difficult to predict outflows from Grand Coulee Dam; however flows large enough to sustain powerhouse operations at Rock Island for at least the daylight hours (preferably all day) would be a benefit to fish passage. 9

FISH PASSAGE CENTER 847 NE 19 th Avenue, #250, Portland, OR Phone: (503) Fax: (503) us at

FISH PASSAGE CENTER 847 NE 19 th Avenue, #250, Portland, OR 97232 Phone: (503) 833-3900 Fax: (503) 232-1259 www.fpc.org/ e-mail us at fpcstaff@fpc.org MEMORANDUM TO: FROM: FPAC David A. Benner DATE: June