Management to Mitigate Environmental Effects of Dams David Rosenberg CEE 6490 – Integrated River Basin / Watershed Planning & Management

Learning Objectives Quantify effects of dams on river channels and indicator species Describe major approaches to mitigate effects Determine effects of mitigation approaches on key indicators CEE 6490

Environmental Effects Altered flow regimes Flood frequency and duration Mean annual flow Base (minimum) flows Temperature Channel degradation Sediment trapping Watershed fragmentation Key indicator species CEE 6490

Historical Longitudinal Bed Profile Glen Canyon Dam, 1956 (Schmidt) CEE 6490

Bed Degradation Glen Canyon Dam, 1956 to 2000 (Schmidt) CEE 6490

Maximum Bed Degradation below some Large Dams (Williams and Wolman, 1984) Colorado Glen Canyon: 7.3 m/9 years Hoover: 7.5 m/13 years Davis: 5.8 m/26 years Parker: 4.6 m/27 years Jemez Jemez Canyon: 2.8 m/12 years Arkansas John Martin: 0.9 m/30 years Missouri Fort Peck: 1.8 m/36 years Garrison: 1.7 m/23 years Fort Randall: 2.6 m/23 years Gavin’s Point: 2.5 m/19 years CEE 6490

Key Indicator Species Typically describe environmental impacts on key indicator species (often a fish!) – NEPA and ESA driven June sucker, Provo River, Utah Azraq killfish, Azraq, Jordan Bonneville cutthroat trout, Bear River Delta smelt, Sacramento & San Joaquin Delta, CA Coho and chinook salmon, Klamath River, CA And many, many, many others Environmental management typically mitigates for species of concern – improve habitat Avoid focus on ecosystem function CEE 6490

Key Indicator Species Salmon Spawning and Ocean Counts, CA CEE 6490

Mitigation Approaches Operational Change timing and duration of releases Structural Multi-stage elevation releases Temperature control structures Thermal curtains Fish screens Fish ladders Management Environmental water accounts Remove dams (possibly in April) CEE 6490

Changing Reservoir Releases Glen Canyon Dam, Colorado River (J Changing Reservoir Releases Glen Canyon Dam, Colorado River (J. Schmidt)

Sediment Reduction (mmt) (A) Pre- and (B) Post-Dam Sediment Fluxes Location Dist. below Dam (km) Sediment Reduction (mmt) Marble Canyon 25 57 to 0.3 Upper Grand Canyon 170 83 to 14 CEE 6490

Significance of Fine-Sediment Deposits Distinctive attribute of the pre-dam riverscape Campsites Creates stagnant flow and backwater habitat at some discharges Riparian ecosystem substrate Deposits contain archaeological resources or stabilize those resources Transport creates turbidity CEE 6490

General Pattern of Sand Bar Change (Badger Creek Rapids) 1956 1999 Sand eroded from eddies Sand eroded by wind; not replaced by flood deposition In the case of Grand Canyon, matched photography and field surveys have allowed us to develop a time series of sand bar elevation that has been pushed back to the 1880s.

Glen Canyon Dam Release Experiments Reduce range of daily fluctuations (erosion control) Spiked “floods” (rebuild high elevation sand bars) Sustain low flows (trap fine sediment)

lost hydropower revenue ~ $1 million November 2004 Sediment Mobilization Flows lost hydropower revenue ~ $1 million CEE 6490

Costs of Modified Releases Release Regime Cost (lost hydro revenue) [$ Millions] Interim low fluctuating flows (per year) $36 Modified low fluctuating flows (per year) $44 1996 controlled flood $4 2003/2004 experimental releases $2.85 (autumn) $1.6 (winter) Restoration budget (FY 2004) $11.1 Annual revenue in 2003/2004 ~ $140 million/yr CEE 6490

Glen Canyon Dam Postscript But … Newly built sand bars were immediately eroded by the large flow fluctuations, designed to disadvantage spawning trout Cutbank 1 day after resumption of large fluctuations CEE 6490

Temperature-Controlled Release Tower Shasta Dam, Sacramento River, CA 4.5 MAF storage Dam height 602 ft. Max. tower depth 350 ft. CEE 6490

Thermal Curtain (Burgi, 1995; Vermeyan, 1995) Lewiston Lake, Clear Creak, California CEE 6490

Comparing Temperature Control Methods (Burgi, 1995) CEE 6490

What did the fish say when it ran into the wall? CEE 6490

Fish Ladders Oroville Dam (right) John Day Dam (bottom right) Bonneville (below) CEE 6490

Fish Ladder at Coleman Fish Hatchery Sacramento River, CA CEE 6490

Fish Screens CEE 6490

Environmental Water Accounts (Hollingshead, 2006) Sac. & San Joaquin Delta 500 plants & animals Supplies 2/3 residential and commercial users 7 million ac farmland 21 Federal & State agencies (i.e, CALFED) Major water exports CVP: 8,000 af/day SWP: 15,000 af/day Endangered species Chinook salman, delta smelt, steelhead rainbow trout CEE 6490

CALFED Operations Purchase assets (year round) Long-term, spot market, and options to water on CA market Storage in reservoirs South of Delta 500 cfs capacity to move purchased assets South of Delta (July to August) Curtail export pumping (critical times to fish) Reimburse projects (SWP and CVP) for cutbacks Deploy purchased assets which are stored South of Delta Real-time operations that respond to ecological and fish events CEE 6490

CALFED Actions $19 – 65 million/year in purchases 155 – 230 TAF/year CEE 6490

Conclusions Can quantify environmental impacts of dams and reservoirs with numerous indicators Site-specific factors determine type and extent of impacts Regulation-imposed mitigation often required Structural, operational, and management approaches to mitigate impacts Often pose significant costs CEE 6490

References Burgi, P. H. "The Evolving Role of Hydraulic Structures - From Development to Management of Water." Issues and Directions in Hydraulics - An Iowa Hydraulics Colloquium, Iowa City, Iowa, http://www.usbr.gov/pmts/hydraulics_lab/history/transition/trans1.html. Hollinshead, S. P., and Lund, J. R. (2006). "Optimization of environmental water purchases with uncertainty." Water Resources Research, 42, W08403, http://dx.doi.org/10.1029/2005WR004228. Mostafa, M. G. (1957). "River-bed degradation below large capacity reservoirs." American Society of Civil Engineers Transactions, 122, 688-704. Vermeyen, T. B. "Use of Temperature Control Curtains to Modify Reservoir Release Temperatures." ASCE's First International Conference on Water Resources Engineering, San Antonio, Texas, http://www.usbr.gov/pmts/hydraulics_lab/tvermeyen/asce95m/index.html. Williams, G. P., and Wolman, M. G. (1984). "Downstream effects of dams on alluvial rivers." Professional Paper 1286, U.S. Geological Survey, Washington, D.C. CEE 6490