Dam Passage Survival - CRiSP.1.5 Theory, Calibration & Validation Manual

II.9.5 - Dam Passage Survival

Fish passing through the dams can take several routes (depicted in Fig. 47). Equations describing the number of fish that pass through each route in terms of the number that enter the dam from the forebay on a particular dam time slice are given below. In each case the mortality and passage efficiencies have deterministic and stochastic parts.

For mortalities and fge, the random elements are represented by additive deterministic and stochastic parts in

(153)

where

x = deterministic part of the random parameter fixed for each species and dam
x' = stochastic part of the parameter taken from a broken-stick distribution (see Stochastic Parameter Probability Density section II.11.1) over each dam time slice.

For spill efficiency, each equation contains a random term. A typical equation is

(154)

where

y = spill efficiency
x = percent flow
a and b = deterministic parameters
e = stochastic parameter selected from a normal distribution.

Turbine Survival

The equation for turbine survival can be expressed

(155)

where

N_tu = number of fish passing in a time increment (2 hrs)
N_fo = number of fish in forebay ready to pass in the increment
p = probability of passing during the increment from eq (136)
m_fo = mortality in forebay (see eq (143))
m_tu = mortality in turbine passage
fge = fish guidance efficiency for a day or night period
y = spill efficiency coefficient (see eq (146))
S = fraction of total flow diverted to spill in the increment
F = flow in increment.

Bypass Survival

The equation for bypass survival without spill is

(156)

where

m_by = mortality in the bypass.

Transport Survival

The equation for transport survival with fixed transport mortality is

(157)

where

m_tr = mortality in the transport.

Users may also choose to relate transport mortality to river flow, via the surrogate of water particle travel time (WPTT). This model, proposed by modelers for the States and Tribes (ANCOOR 1994), relates transport survival to flow/travel time as follows:

For flows equal to or greater than those in 1986, transport mortality is determined assuming a transport-benefit ratio (TBR) of 1.01 to 1 for fish released at Little Goose tailrace. This means that the ratio of returning adults from transported groups to non-transported groups will be 1.01 to 1.
For flows equal to or lesser than those in 1977 (a very low-flow year), the TBR for Little Goose is assumed to be 3 to 1.
For flows intermediate between 1977 and 1986 conditions, transport mortality is obtained by linear interpolation between those two end points.

The motivation for this model is that fish condition deteriorates with increasing residence time in the system, which could have a negative impact on survival through the presumably stressful process of being collected for transport. The results are illustrated as transport mortality as a function of system WPTT, remembering that as flows decrease, travel times increase. This is shown in Fig. 62 below.

The transport mortalities derived will depend on how the model in question calculates WPTT and also how it calculates the in-river survivals used to back-calculate transport survivals from TBR data; the figure below uses CRiSP calibrated values.

Fig. 62 Transport survival as a function of flow.

Spill Survival

The equation for spill survival is

(158)

where m_sp = mortality in the spill passage.

Calibrating Passage Mortality

Turbine mortalities used in CRiSP.1.5 are generally 30% lower than values used in other salmon passage models including CRiSP.1 version 3. The lower values reflect the fact that CRiSP.1 accounts for additional delayed turbine passage mortality in the tailrace through an increased predation activity coefficient that reflects the vulnerability of fish immediately after dam passage.

Direct measure estimates are from

Oligher, R. C. and I. J. Donaldson. 1966

Weber, K. G. 1954.

Indirect measure estimates are from

Holmes, H. 1952.

Schoeneman, et al. 1961.

Long, C. W. 1968.

Long, C. W., F J. Ossiander, T. E. Ruehle and G. Mathews.

Raymond (1979)

Raymond and Sims (1980)

Ledgerwood, R.D. et al. 1990.

The recent measurements of turbine survival with inflated tags and PIT tags are given in Table 53.

Table 53 Recent turbine mortality estimates
Dam Species	Mortality estimate	Technique	Reference
Rocky Reach yearling fall chinook	5.6%	inflated tags	RMS Environmental Service, Inc. and J.R. Skalski. (1993)
Lower Granite spring yearling chinook	6.6%	inflated tags	RMS Environmental Service, Inc. and J.R. Skalski. (1994)
Lower Granite spring yearling chinook	17.3%	PIT tags	Iwamoto et al (1994)
Little Goose spring yearling chinook	8.0%	PIT tags	Iwamoto et al (1994)
Lower Monumental spring yearling chinook	13.5%	PIT tags	Muir et al (1995)
Lower Granite spring yearling chinook	7.3%	PIT tags	Muir et al (1996)
average	9.7%	-	-

Bypass and spill mortalities are based on the following studies. Full citations are given in the reference chapter.

Ceballos, J., S. Pettit, and J. McKern. 1991.

Ledgerwood, R. et al. 1990.

Ledgerwood, R. et al. 1991.

Muir et al (1996)

Passage mortalities used in calibration, including mean, low and high values, are given in Table 54. The mortalities are used for all species but most of the data was from studies involving spring chinook. The estimates are weighted towards the more recent studies. High estimates of dam passage mortality in 1972-1973 are used to represent documented problems in Snake River dam passage in these years. The high mortalities were assigned to both turbine and bypass routes.

Table 54 Percent mortality at dams: m = mean, l = low, h = high. These mortality estimates are applied to spring chinook in analysis up through 1995.
Dam	Spillway			Bypass			Turbine			Comments
Dam	m	l	h	m	l	h	m	l	h	Comments
All dams except where noted	2	0	7	2	0	8	7	1	10	-
Monumental ^a 1972	2	0	7	2	0	8	7 50	1	10	- slotted bulkheads
Little Goose ^b 1972 1973 1974	2	0	7	2 40 50 11	0	8	7 40 50 11	1	10	- slotted bulkheads bad fish condition -
Lower Granite 1979 ^c	2	0	7	2 27	0	8	7 27	1	10	- trash problem

^aRaymond 1979
^bRaymond 1979
^cRaymond and Sims 1980

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