Category Archives: Northern California

Another Salmon Hit for 2017

Posted on by

Shasta Dam releases were cut by a third during the first week of November, dropping water levels in the Redding salmon spawning reach by one to two feet (Figures 1 and 2). Delta CVP export demands declined, water temperatures dropped, and rain contributed modest flows from lower Sacramento tributaries, thus minimizing need for Shasta releases. Fall X2 flows are no longer are needed in the Delta. Might as well cut Shasta flows to save water for next year!

But somebody forgot that tens of thousands of spring-run and fall-run salmon that just finished spawning in the 50 miles of river below Shasta around Redding, Anderson, and Red Bluff! Will the water level drop hurt the fresh spawning redds? Yes, most certainly!

Figures 3 and 4 show depth use and optimum suitability for fall run Sacramento River spawners. The most used depth and optimum suitability for salmon spawning is between one and two feet. A one to two foot drop in water levels after spawning is not likely to create a good outcome. It would dewater many redds. It would lower flows and provide less oxygen, and more siltation in the redds that remained in the water, causing significant egg/embryo mortality of the eggs that survive the initial drop in the water level. These conditions could lead to a major loss of wild salmon production.

There is no valid reason for cutting the flows. Shasta storage is 3.15 million acre-ft, 120% of normal, near the all-time record of 3.25 maf for November. Who is guarding the henhouse? Where is that wonderful adaptive management federal and state agencies brag about?

Figure 1. River stage below Keswick Dam, Oct-Nov 2017.

Figure 2. River stage at Bend Bridge near Red Bluff, Oct-Nov 2017.

Figure 3. Habitat suitability and use of fall run salmon by water depth for spawning. (USFWS)

Figure 4. Habitat suitability and use of fall run salmon for spawning. (USFWS)

Enhancing Oroville Hatchery Salmon Contribution

Posted on by

In a recent post, I discussed ways to increase returns/survival of the Coleman (Battle Creek) Hatchery produced smolts released to the Sacramento River and the Bay. In this post I focus on ways to improve returns/survival of young salmon produced at the Oroville (Feather River) Hatchery. Trucking smolts to the Bay in drier water years and releasing spring flow pulses in wetter years remain the key management actions for increasing the contribution of hatchery salmon to coastal and river fisheries. Timing of releases is also critical. While overall returns are highly influenced by ocean conditions, active management by hatchery managers (trucking, barging, and timing of releases) and water managers (flow pulses) are important tools in maximizing the contribution of hatchery smolts to salmon populations.

In a prior post, I discussed general means of increasing hatchery contributions. In that post, I presented a summary of Oroville (Feather River) Hatchery returns for brood years 2008-2012 (Figure 1). Return rates were highest for brood years 2009-2011, with winter-spring normal-wet year designations (water years 2010-2012). Brood year 2008 and 2012 smolts were released in winter-spring of drought years.

In this post I provide information from earlier brood years. This information supports a more specific strategy to increase the Feather River hatchery program’s contribution to California fisheries. Below, I add a summary of returns from selected brood years (2002-2007).

Figure 1. Feather River hatchery fall-run salmon return rates by release method for brood years 2008-2012 (release years 2009-2013). Source of data: http://www.rmpc.org/

Brood Year 2002

Hatchery smolt returns for brood year 2002 were good, with hatchery releases in the above-normal water year 2003. The good adult return performance is generally attributed to good river and ocean conditions in 2003. A closer look at release return rates (Figure 2) shows generally good returns (>1%) reflecting the good river and Delta conditions in 2003 and good ocean conditions, at least in 2003. Some return rates were very good (>2%), including late April to mid-May returns for Delta and Bay (non-pen) releases. The higher return rates occurred coincident with a late-April through mid-May flow pulse (Figure 3). During the flow pulse, releases to the Delta had return rates in the same high range as Bay releases. Most of the river releases had low rates of return (<1.0%) before the flow pulse; while during the pulse, most rates were 1.0-1.7%.

Figure 2. Feather River hatchery fall-run salmon return rates by release method for brood year 2002 (release year 2003). Source of data: http://www.rmpc.org/

Figure 3. Water temperature and mean daily river flow in the lower Sacramento River channel of the Delta at Freeport in spring 2003. (USGS chart)

Brood Year 2003

Hatchery smolt returns for brood year 2003 were mediocre. The juvenile salmon were released in the below-normal water year 2004. The poor performance is generally attributed to poor river conditions in 2004 and poor ocean conditions in 2004-2006. A closer look at release return rates (Figure 4) shows few good returns (>1%); this reflects the poor river and ocean conditions. Some Bay-release return rates were good (>1%). The higher Delta-release and Bay-release return rates occurred with higher early-to-mid April flows (Figure 5). May river releases had near-zero rates of return. Overall, Bay-release return rates (all with net pens) far outperformed Delta and river releases, reflecting the advantage of bypassing poor river and Delta conditions after mid-April in 2004.

Figure 4. Feather River hatchery fall-run salmon return rates by release method for brood year 2003 (release year 2004).

Figure 5. Water temperature and mean daily river flow in the lower Sacramento River channel of the Delta at Freeport in spring 2004. (USGS chart)

Brood Year 2004

Hatchery smolt returns for brood year 2004 were poor despite the fact that juvenile releases took place in the above-normal water year 2005. The poor performance is generally attributed to poor ocean conditions in 2005-06. A closer look at release return rates (Figure 6) shows poor returns (<1%) reflecting the poor ocean conditions. Some return rates were extremely poor (<0.01%). Compared to good return rates of 1-4% in other years (see Figure 1), these rates are extremely low. For example, a normal annual release of 4 million smolts from the Oroville Hatchery would return 40,000 adults at 1% and only 400 at 0.01%. A closer look at Figure 6 release rates and water conditions in spring 2005 (Figure 7) indicates higher survival of releases into the Feather River and Bay during the May flow pulse, although Bay release rates (all net pens) averaged twice those of river releases.

Figure 6. Feather River hatchery fall-run salmon return rates by release method for brood year 2004 (release year 2005).

Figure 7. Water temperature and mean daily river flow in the lower Sacramento River channel of the Delta at Freeport in spring 2005. (USGS chart)

Brood Year 2005

Brood Year 2005 releases in the very wet year 2006 had return rates that were very poor for both Delta and Bay releases, reflecting very poor ocean conditions (no chart shown). Delta releases averaged 0.1 % return, with Bay releases (no pens) only slightly higher at 0.2 %. These low rates, along with similar low rates from other Central Valley hatcheries, contributed to the salmon fishery collapse of 2008.

Brood Year 2006

Hatchery smolt returns for brood year 2006 were poor (Figure 8). The poor performance is generally attributed to poor river, Delta, and Bay conditions in the 2007-2009 drought, and mediocre ocean conditions. Many return rates were very poor (<0.1%). Some of the higher returns came from earlier releases (April), when Delta inflow was higher and water temperatures were lower (Figure 9).

Figure 8. Feather River hatchery fall-run salmon return rates by release method for brood year 2006 (release year 2007).

Figure 9. Water temperature and mean daily river flow in the lower Sacramento River channel of the Delta at Freeport in spring 2007. (USGS chart)

Brood Year 2007

Hatchery smolt returns for brood year 2007 were generally poor (Figure 10). The poor performance is generally attributed to poor river, Delta, and Bay conditions in the 2008-2009 drought, and relatively poor ocean conditions, except in 2010. Many return rates were very poor (<0.1%). Some Bay pen release return rates were good (>1.0%). Most of the lower return rates came from May river releases under poor conditions (Figure 11). Bay pen release return rates were generally substantially higher than non-pen Bay releases during May.

Figure 10. Feather River hatchery fall-run salmon return rates by release method for brood year 2007 (release year 2008).

Figure 11. Water temperature and mean daily river flow in the lower Sacramento River channel of the Delta at Freeport in spring 2008. (USGS chart)

Summary and Conclusions

In summary, return rates from Oroville Hatchery fall-run salmon smolt releases vary greatly with ocean, river, Delta, and Bay conditions, within and among years. With up to 6 to 8 million fall-run smolts released each year, highly variable return rates result in highly variable catches of adult fish in coastal and river fisheries and spawner escapement to rivers and hatcheries. Good years can yield 1 or 2 percent total returns – producing 60,000-160,000 adult salmon returns. Poor years may yield only 0.1% or less – just 6,000-16,000 adult returns. Factors affecting the return rate include:

  1. Ocean conditions.
  2. River, Delta, and Bay conditions.
  3. Release location – Feather River, lower Sacramento River below mouth of Feather, north Delta, San Pablo/North Bay, and coastal bays north and south of San Francisco.
  4. Release method – trucked to river, Delta, or Bay boat ramps for direct release, trucked to acclimation pens in Delta or Bay, or trucked to feeding pens in coastal bays.
  5. Age/size of released smolts – February through July: early spring smolts, normal spring smolts (mid-April to mid-May), and advanced late spring smolts (mid-May to mid-June). Late spring releases are limited to the Bay because the rivers and Delta are too warm.
  6. Date of release – winter release of hatchery fry and fingerlings, spring release of smolts, late spring and summer release of advanced smolts.

The following actions by hatchery and resource managers can enhance returns to a limited extent, depending on conditions.

  1. Trucking to lower Sacramento River, Delta, Bay, or coastal bays.
  2. Acclimating trucked fish in pens prior to release.
  3. Timing releases to best available release conditions.
  4. Enhancing release conditions (e.g., flow pulses).
  5. Barging smolts to the Bay from the lower Feather River.

The most problematic situation for managers is improving returns in years with very poor ocean conditions (e.g., 2006). Under such conditions, trucking to Bay pens appears to be the best option and is the present management scheme. Barging smolts to the Bay may provide an added benefit. Under good ocean, Bay-Delta, and river conditions, releases to river and Delta locations with a supplemental flow pulse may provide good returns. Releases to lower Feather River locations generally provide poor returns regardless of conditions.

A further enhancement option is rearing hatchery fry in floodplain rice fields adjacent to the lower Feather River. Besides the obvious benefit of “natural” rearing, high growth would allow smolt release at least a month earlier than hatchery smolts. Such natural smolts could be trucked or barged to the Bay from near the rearing sites. A return rate of 5-10% from such smolts is conceivable, with the potential of contributing substantially to coastal and inland salmon fisheries.

Webber Lake

Posted on by

Webber Lake is a natural Sierra lake at 6500’ elevation north of Truckee. Located in the Little Truckee River headwaters, it was recently purchased and opened to the public by Tahoe-Donner Land Trust.1

Webber Lake was once renowned for big trout (privately stocked), but it is now a put-and-take fishery with a few holdovers (standard trout fishing regulations). The lake so far has no milfoil (boats and float tubes must be “certified” by staff). It has nice pond weed beds with abundant red shiners. It is a relatively small but deep (> 40’). The lake and valley are very quiet and pristine. Eagles, osprey, terns, and cranes are common.

The lake is situated off Hwy 89 on the way to Portola in a serene mountain valley. The adjacent mountains still have late summer patches of snow. It has a nice campground ($30; 35 widely spaced sites in woods next to lake) and day-use parking area (no fee). An RV camp will open next year.

The fishery is now managed by CDFW with mostly small 8-inch planter rainbow trout and holdovers from prior years’ stocking. I have not heard of any recent catches of browns or brookies, though in the past both were commonly stocked. Natural spawning creeks that can support wild trout flow into the lake.

It is sad to see this natural gem managed as another put-and-take trout lake like most of its neighbors (Davis, Frenchman, Gold, Boca, and Stampede, etc.). It could be managed as a wild trout lake, on the model that the Nature Conservancy now manages nearby Independence Lake.2 DFW has recently started stocking Webber Lake with Lahontan cutthroat, the native trout of the Truckee watershed. This suggests that management of the lake for wild native trout might be considered in the future.

WaterFix NMFS Biological Opinion Conclusions on Salmon in the Delta

Posted on by

The National Marine Fisheries Service’s biological opinion (NMFS BO) on the proposed “California WaterFix” (Delta Twin-Tunnels Project) concludes there will be no significant effect on protected salmon, steelhead, and sturgeon in the Central Valley. In this post, I address the conclusions in the NMFS BO on the potential effects of WaterFix on salmon and steelhead in the Delta. This is one in a series of posts on the WaterFix. Within that series, it is the second post of the series on the NMFS BO.

The NMFS BO concludes that WaterFix operations would have significant adverse effects on salmon, steelhead, and sturgeon and their critical habitat in the Central Valley from changes brought about by the WaterFix Twin Tunnels Project. In contrast, the NMFS BO also states that the WaterFix is not likely to jeopardize the species or adversely modify their critical habitat. How such contradictory conclusions are possible, especially for the rather demonstrable Delta effects, is simply beyond reason. Previous drafts of the BO had not made that jump. There is no amount of adaptive management within reason, especially given past poor performance in operating the water projects and managing effects on fish, that can alleviate the potential great risks to Central Valley fishes from the adding the WaterFix Twin Tunnels to the state and federal water projects.

The “new” NMFS BO focuses on changes in flow patterns in the Delta below the three proposed diversion points in the North Delta. The diversions of up to 9,000 cubic feet per second (cfs) would change flow and flow splits downstream in Steamboat, Sutter, and Georgianna sloughs and the Delta Cross Channel, as well as in the main Sacramento River channel. As a consequence, freshwater flows entering the interior Delta from the north Delta would also change, as would Delta outflow to the Bay to the west. Young salmon, steelhead, and sturgeon from the Sacramento River and San Joaquin River basins would be affected by these changes upon entering the Delta on their way to the Bay and ocean.

The NMFS BO concludes that the up-to-9000 cfs diversion of the WaterFix would reduce channel velocities below the intakes in the north Delta. “Under the PA [Proposed Alternative] water velocities in the north Delta would be lower…. This would increase migratory travel time and potentially increase the risk of predation for juvenile salmonids.” (p. 602) In the past, based on my own assessments, survival of hatchery and wild salmon and steelhead to the Bay may have been reduced by 50-to-90 percent based on differential survival of marked hatchery smolts released above and below the Delta under differing flow regimes. The NMFS effects assessment is based on survival of radio tagged, large, late-fall hatchery smolts during the winter; this indicates just a small differential in survival. The real effect is likely somewhere in between and highly variable depending on a wide range of circumstances. No doubt a serious concern remains for the future of the various listed species and success potential of future commercial and recreational fisheries.

The greatest risks are to pre-smolt winter-run salmon in the fall season and to juvenile spring-run and fall-run salmon and steelhead in the spring.

“In the South Delta, median velocities generally increase under the PA…. The positive change in velocity would decrease migratory travel time and reduce predation risk for juvenile salmonids.” (p. 602) The conclusion is that exports from the south Delta will decline from November through June because of WaterFix. That simply is not true, because south Delta exports are already constrained during those months. WaterFix would not change those overall constraints; it would only add to the overall diversion capacity. Export restrictions based on net flows will remain the same; thus there will be no changes in rules governing the south Delta exports. Furthermore, the 9,000 cfs taken by WaterFix will reduce Sacramento River freshwater inflow into the central and south Delta, increasing any effects of south Delta diversions on the interior Delta’s hydrodynamics. The relative effects on San Joaquin River Delta inflows will remain the same or even increase.

“In the Central Delta, there is little difference in magnitude of channel velocities between the NAA [No Action Alternative] and PA.” (p. 602) While it is true there is little difference for channel velocities in this highly tidally driven region, it is not true for freshwater inflow, salinity gradients, and water temperatures, or for relative flow signature differences for the San Joaquin and Sacramento Rivers within the central Delta. The loss of Sacramento River freshwater inflow into the central Delta via Georgianna Slough and the Delta Cross Channel (when open) is significant. Tidal inflows from the west Delta into the central and south Delta in the San Joaquin and False River channels will increase, potentially reducing survival of San Joaquin salmon and steelhead. Sacramento River salmon and steelhead survival, already reduced by lower flows below the tunnel intakes, would be further reduced by lower survival of fish that passed through Georgianna Slough or the Delta Cross Channel, or through cross-Delta movement through Three-Mile Slough.

“In the North Delta, reverse flows would increase in most water years and months…. In the North Delta, the PA had a higher proportion of each day with negative velocities (reverse flow) particularly in Steamboat Slough and Sacramento River downstream of Georgiana Slough”. (p. 602) The loss of freshwater inflow to the WaterFix Twin-Tunnel diversion would decrease the extent in location and timing of unidirectional flow in the tidal Sacramento River (Figure 1). Diversions during times when Freeport flows were in the range of 15,000-35,000 cfs would change the river from virtually non-tidal to tidal.

Figure 1. Example period: flows at Freeport March-July 2017. Red arrow denotes 9,000 cfs WaterFix tunnel diversions above the 35,000 cfs inflow. WaterFix diversions would be minimal below 15,000 cfs inflow. Green line denotes point at which flow would become tidally influenced with WaterFix as seen after June 15 when hourly flows varied from 5000 to 15,000 cfs during a tidal cycle. Note: for location of gages, see Figure 4 map.

The effect downstream at the flow splits of the Sacramento River at Georgianna Slough and Steamboat Slough is even more pronounced (Figures 2 and 3). In the Sacramento River below the Georgianna Slough split, flood tides would turn negative earlier in the season with upstream WaterFix diversions (Figure 2). Likewise, Steamboat Slough flood tides would turn negative with WaterFix when Freeport flows fall to 25,000 cfs. In 2017, that would have meant negative flows nearly a month earlier with WaterFix (Figure 3). Not only do WaterFix diversions reduce flows in the northern Delta channels, they would turn migration period conditions poorer (reverse flows and higher water temperatures) nearly a month earlier than under present conditions. “In order to more thoroughly evaluate the impact of reverse flows on migrating salmon, NMFS undertook an additional analysis. The likelihood of juvenile fish entering migratory routes with reduced survival increases with the daily probability of flow reversal, or with increases in the proportion of each day with flow reversals. The probability of juvenile Chinook salmon getting entrained into migratory routes of lower survival like Georgiana Slough and the Delta Cross Channel is highest during reverse-flow flood tides (Perry et al. 2015). In addition, the proportion of fish entrained into Georgiana Slough on a daily basis increases with the proportion of a day that the Sacramento River downstream of Georgiana Slough flows in reverse (Perry et al. 2010). Consequently, diverting water from the Sacramento River could increase the frequency and duration of reverse-flow conditions, thereby increasing travel time as well as the proportion of fish entrained into the interior Delta where survival probabilities are lower than in the Sacramento River (Perry et al., 2010 and 2015)…. In the north Delta, increase in flow reversals downstream of Georgiana Slough are of concern for migrating salmonids…. Increases in flow reversals would likely reduce the survival probability of outmigrating smolts by moving them back upstream, increasing their exposure to junctions that lead to migratory routes of lower survival, such as in Georgiana Slough.” (p. 603)

Figure 2. Example period: flows at Georgianna Slough flow split March-July 2017. Red line notes when condition in Sacramento River below Georgianna Sough at which flood tides reverse river flow – when Freeport flow is below 25,000 cfs. In contrast, flows in Georgianna Slough would not become negative.

Figure 3. Example period: flow in Steamboat Slough below split March-July 2017. Flow in Steamboat Slough becomes negative when Freeport Sacramento River flow falls below 25,000 cfs. Under WaterFix, Steamboat Slough flows could become negative at Freeport flows below 34,000 cfs.

“The proposed NDD bypass rules include a commitment to an operational constraint that the amount of flow withdrawn at the NDD cannot exacerbate reverse flows (i.e., increase the frequency, magnitude, or duration of negative velocities) at the Georgiana Slough junction from December through June beyond what would occur in NAA. However, the BA does not describe the methods or the modeling that would show how this would be achieved. Specifically, the BA does not describe: 1. The extent that the proposed NDD bypass rules may affect the frequency, magnitude and duration of reverse flows in the lower Sacramento River; 2. The description of how real-time monitoring could be implemented to meet the criteria of not increasing reverse flows; 3. The modeling simulations that would show how this criteria is being met and therefore provide reasonably accurate bypass flow levels.” (p. 603).

In the example shown in Figures 2 and 3 above, WaterFix diversions would exacerbate reverse flows unless no diversion was allowed below a 35,000 cfs Freeport flow, a commitment not made in WaterFix proposal.

This is a major flaw in the NMFS BO assessment. Even NMFS acknowledges this fact: “The probability of a flow reversal in the Sacramento River downstream of Georgiana Slough occurring at some time during a 24-hour period is one hundred percent when Sacramento River flows at Freeport are less than 13,000 cfs (Figure 2-118 top panel). Likewise, when flows are greater than 23,000 cfs, flow reversals are not expected to occur at the Georgiana Slough junction.” (p. 606) A flow of 23,000 cfs would occur below the tunnel diversions when Freeport flow is 32,000 cfs.

“The following assumptions were used: 1) the NDD bypass rules are applied based on mean daily Sacramento River discharge at Freeport, and 2) water is diverted at a constant rate over an entire day such that the bypass flow is constant over the day. The analysis adheres to a strict interpretation of the NDD bypass rules and does not include flow variations at sub-daily timescales.” (p. 606) Note that diverting 9000 cfs on a flood tide with Freeport flow at 30,000 cfs would cause a flow reversal in Steamboat Slough and in the Sacramento River below the split at Georgiana Slough (Figures 2 and 3).

“October-November operations can greatly increase the probability of reverse flow; for example, when flows at Freeport are between 20,000 to 25,000 cfs there would be ~100% increase in flow reversals under the PA (Figure 2-124)… .(p. 606) The months with the largest increases in travel time for both the PA and L1 occur during the off-peak Chinook salmon migratory months of October, November, and June. During the peak Chinook salmon migratory window of December through April, February and March have the largest increases in travel time under the PA.” (p. 615) Such flows may occur in October-November from early storms, and a large influx of winter-run salmon pre-smolts would be expected to enter the north Delta under these circumstances. NMFS expects that restrictions on diversions during early pulses and changes to Delta Cross Channel operations would protect winter-run.

“However, if flow in November becomes sufficient through storm runoff events to trigger winter-run emigration towards the Delta, a pulse protection will apply that will limit diversions to low level pumping for a certain amount of days or until fish presence is not detected based on real-time management criteria. Without this protection, early emigrating winter-run would be subject to some of the more extreme diversion levels allowed, probability of reverse flows would increase, and winter-run Chinook salmon would face greater risk of entrainment into interior Delta and overall lowered survival.” (p. 625) WaterFix does not propose to protect all fall pulses, nor winter flow pulses. There would be no restrictions on south Delta diversions, which would be 11,400 cfs under these conditions. The WaterFix would thus exacerbate the existing level of impacts, which are quite serious in the fall of wetter years.

NMFS also notes potential serious consequence to spring-run and fall-run salmon: “May has a unique set of NDD bypass rules that is slightly less protective than the diversion rules in December through April because Level 2 or 3 could be enacted if bypass flow criteria have been met. 5% to 13% of spring run Chinook salmon smolts are expected to be in the Delta during this month (Table 2-171). They may experience slightly longer travel times than smolts traveling during earlier months given the same inflow at Freeport. This would be due to lower velocities that may result from less restrictive diversions as defined by the NDD bypass rules.” (p. 631) Most Sacramento Valley hatchery fall-run smolts are released into rivers or the Delta in late April and early May – they too are vulnerable to WaterFix-induced reverse flows in the Delta.

  • NMFS eventually concludes that reductions in survival in the north Delta are balanced by increased survival in the south Delta: “Interpretation of these analyses must also consider that small changes in absolute survival could translate to a large effect to a population, especially in years when overall Delta survival is low. The 2-7% increase in Delta survival that would occur if entrainment into the interior Delta were eliminated (Perry et al. 2012) resulted in a 10-35% relative change in survival for five of the six release groups in that study.” (p. 663) First, there is no basis to the assessment findings that Delta exports, already restricted in the December to June period, would be further restricted with WaterFix. Second, the assessment of the south Delta effects did not take into account the added stress of reduced inflow of Sacramento River water into the interior Delta because of WaterFix. NMFS qualifies its own conclusion: “The extent to which management actions such as reduced negative OMR reverse flows, ratio of San Joaquin River inflow to exports, and ratio of exports to Delta inflow affect through-Delta survival is uncertain.” “Uncertainty in the relationships between south Delta hydrodynamics and through-Delta survival may be caused by the concurrent and confounding influence of correlated variables, overall low survival, and low power to detect differences.” (p. 687)

NMFS concludes no adverse effects: “After reviewing and analyzing the current status of the listed species and critical habitat, the environmental baseline within the action area, the effects of the proposed action, any effects of interrelated and interdependent activities, and cumulative effects, it is NMFS’ biological opinion that the proposed action is not likely to jeopardize the continued existence of Sacramento River winter-run Chinook salmon, CV spring-run Chinook salmon, CCV steelhead, Southern DPS of North American green sturgeon or destroy or adversely modify designated critical habitat for these listed species.” (p. 1111) The basis for these conclusions appears to be balancing of north Delta negative effects with south Delta benefits, as well as the adaptive management capability offered by WaterFix.

In summary, then:

  • NMFS has understated the potential effect of the WaterFix on salmon migration survival through the Delta and the potential to minimize tidal effects based on WaterFix’s proposed rules and commitments. “(I)n the May 2016 Revised PA, DWR committed to Delta habitat restoration at a level that RMA Bay-Delta modeling indicates could prevent exacerbation of reverse flows in the north Delta due to the PA by changing the tidal prism in the Delta (see Section 2.5.1.2.7.1.2 NDD Bypass Flows and Smolt Entrainment Analysis).” (p. 623)
  • NMFS has overestimated the potential benefits of changes in the south Delta.
  • Based on past experience, NMFS’s assumption that real-time management of Delta operations by DWR and Reclamation (USBR) can overcome potentially damaging conditions is unfounded.

Figure 4. Map of key north Delta flow measurement locations.
“A” is Sacramento River at Freeport.
“B” is Sutter-Steamboat Slough.
“C” is Sacramento River below outlet to Georgiana Slough.
“D” is Georgianna Slough.

Sometimes it doesn’t take a lot of water.

Posted on by

In a May 29 post, I discussed how a small diversion of cold water from the West Branch of the Feather River sustains the Butte Creek spring-run Chinook salmon, the largest spring-run salmon population in the Central Valley. In a May 8 post, I described how the Shasta River, despite its relatively small size, produces up to half the wild fall-run Chinook salmon of the Klamath River. In both examples, it is not the amount of water, but the quality of the water and the river habitat that matters. In the former case, man brought water to the fish. In the latter, man returned water and habitat to the fish.

While both examples are remarkable given the relatively small amount of water involved, the relatively small restoration effort required on the Shasta River and the minimal effect on agricultural water supply make it almost unique.

Just take a look at the present late May 2017 hydrology of the Klamath River (Figure 1). There was only 140 cfs flowing in the lower Shasta River. At the same time, there was 25,000 cfs flowing in the lower Klamath, 2000 cfs in the upper Klamath below Irongate Dam, and 2000 cfs in the Scott River. What is different is that most of the Shasta flow is spring fed, some of which is sustained through the summer. Of the roughly 300 cfs base flow in the river in late May 2017, about 200 was from springs (Figure 2). By mid-summer, flow out of the Shasta River into the Klamath will drop to about 50 cfs, with agricultural diversions from the Shasta at about 150 cfs. October through April streamflow is generally sufficient to sustain the fall-run salmon population. Summer flows are no longer sufficient to sustain the once abundant Coho and spring-run Chinook salmon.

Figure 1. Lower Klamath River with late May 2017 streamflows in red. Note Shasta River streamflow was only 140 cfs near Yreka, California. Data source: CDEC.

Figure 2. Selected Shasta River hydrology in late May 2017. Roughly 150 cfs of the 300 cfs total basin inflow is being diverted for agriculture, with remainder reaching the Klamath River. Red numbers are larger diversions. The “X’s” denote major springs. Big Springs alone provides near 100 cfs. Of the roughly 100 cfs entering Lake Shastina (Dwinnell Reservoir) from Parks Creek and the upper Shasta River and its tributaries, only 16 cfs is released to the lower river below the dam. Red numbers and arrows indicate larger agricultural diversions. Up to 15 cfs is diverted to the upper Shasta River from the north fork of the Sacramento River, west of Mount Shasta.