# Presentation: 166724

## Columbia River Basin Dams

-  FCRPS--29 federal dams (USACE and BOR)
- Hydropower (50-65% of the region’s needs)
- Flood control
- Irrigation
- Recreation
- Navigation
- Non federal
- Mid Columbia PUD (Chelan, Grant, Douglas)
- Hells Canyon Complex (Idaho Power)
- Other
- Hundreds of push-up irrigation and recreational dams

**Notes:**
The Columbia River Basin, which drains some 259,000 sq miles and defines the PNW is, along with the Mississippi, is among the world’s most dammed and regulated rivers

There are  29 federally owned and operated dams that produce hydropower, and provide for flood control, irrigation, recreation, and navigation

There are in addition 5 major dams on the mid-Columbia owned and operated by the PUDs of Chelan, Douglas, and Grant counties, and another 3 in Hell Canyon on the Snake owned and operated by Idaho Power.

Fortunately, many of these do have provisions for fish passage.

## Columbia River at The Dalles (1970-1999)

-   Virgin flow: observed flow corrected for reservoir manipulation and irrigation depletion and return
-   Adjusted flow: river flow adjusted for irrigation water withdrawal and return
-   Observed flow: Empirically measured flow at a gauge

**Notes:**
Virgin flows:  the estimate of river flow as it would be without human alteration (I.e., the observed flow corrected for reservoir manipulation and irrigation depletion and return flows

Adjusted flow:  the estimate of river flow adjusted for irrigation water withdrawal and return 

Observed flow:  the empirically measured flow at a gauge

Characteristics of the spring freshet:  peak flow reduced ca. 40%; duration compressed by 30%; increased fall and winter flows.  These changes can have profound effects on the estuary and the plume 

## Estuary

- recoveries

**Notes:**
Currently, PIT tag detectors are operational at all Snake River dams save Ice Harbor, and all lower Columbia River dams save The Dalles; we also have an experimental trawl operating in the CRE that allows detections.

A computer model (SURPH) developed by John Skalski and Steven Smith (based on the early mark/recapture techniques developed by Jolly Seber Cormack) is used to estimate reach survivals...with a reach defined as the tailrace of one dam to the tailrace of the next dam downstream.

Relationship between flow and survival, flow and travel time, and other biophysical relationships can be analyze by statistical regression.  R2 is the % of variability in the dependent variable (survival or travel time) explained by variation in the independent variable (flow, turbidity, temperature).  The next several overhead show examples of these kinds of analyses 

## Smolt Survival Studies 1995-1997

*Fall chinook salmon:  flow vs. survival*

**Notes:**
Fall Chinook salmon:  Survival probability regressed on flow; R2 = 48.3%

This means that almost half the variation in survival is explained by flow (turbidity or temperature)

So...Taking into account all the empirical information from 1993 to present, we can characterize the relationships as follows 

## Columbia River Plume:  June 1999 vs. June 2001

**Notes:**
The Columbia River plume, once a major oceanographic feature of the Pacific coast (detectable as far south as San Francisco) is markedly reduced even on average year such as 1999 (average flow = 360 kcfs), let alone a drought year such as 2001 (average June flow = 160 kcfs).

We are just now beginning to understand the importance of the plume system as a dynamic habitat that is rich in nutrients and affords sage harbor as the emerging smolts adapt to seawater and grow before moving offshore for blue water. 

Average flow in June 1999 = 344 kcfs
Average flow in June 2001 = 137 kcfs

Ongoing research demonstrating the importance of the plume as a habitat...chum and pink salmon hangout on the outside margins of the front, coho in the front, and Chinook on the inside of the front.  Volume of discharge directly influences the amount of this habitat.

## Ocean Transition and Riverine Plume Dynamics

-  Physical dynamics
- - temporal and spatial distribution of fronts and eddies; mixing and convergent zones
-  Trophic dynamics
- - primary and secondary production
- - predator-prey interactions
-   Distribution, growth, and survival of salmon

*A critical habitat transition*

## Conclusions

- Water is more than the medium in which salmon live...it is a dynamic force in shaping habitats and influencing survival throughout the complex life cycle
- The flow-travel time-survival relationship for selected species of migrating juvenile salmon is an example of such an ecological service.
- Significant progress is being made in understanding such ecological services in spawning and rearing and in estuarine and nearshore ocean habitats.