Water Resources Planning Lesson Topic: Environmental Effects of Dams Instructors: David Rosenberg and Steve Burian

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

 Student suggestions… Environmental Effects of Dams

Bed Degradation What depth of degradation is possible…over how long of a time period?

Sediment Trapping Facts: storage capacity in reservoirs is reduced each year by sediment accumulation: –Average of 0.2% annual reduction in U.S. –Average of 0.5% annual reduction in Pacific states of U.S. –Average of 2.3% annual reduction in China Activity: –Work in pairs –Use Internet or other source to find value of annual reservoir capacity reduction from sediment trapping –Use value you find (or an assumed reasonable value) and calculate the time (in years) it will take to reduce reservoir storage capacity to 75% of its original capacity –Insert values into GoogleSheet (

Sediment Trapping - References Table 3.3 in: reports/200102Sedimentation%20in%20storage%20reservoirs.pdfhttp:// reports/200102Sedimentation%20in%20storage%20reservoirs.pdf Annandale, G. W. (2006). "Reservoir Sedimentation." Encyclopedia of Hydrological Sciences, John Wiley & Sons, Ltd. Crowder, B. M. (1987). "Economic costs of reservoir sedimentation: A regional approach to estimating cropland erosion damage." Journal of Soil and Water Conservation, 42(3), HDR. (2010). "South Fork Rivanna Reservoir Dredging Feasibility Study: Dredging Alternatives Study." Rivanna Water and Sewer Authority, Charlottesville, VA. Hotchkiss, R. H., and Huang, X. (1994). "Reservoir sediment removal: hydrosuction dredging." Hydraulic Engineering, 2, Palmieri, A., Shah, F., and Dinar, A. (2001). "Economics of reservoir sedimentation and sustainable management of dams." Journal of Environmental Management, 61(2),

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

Blocking Fish Migration

Key Indicator Species Typically describe environmental impacts on key indicator species (typically 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 to mitigate for species of concern – improve habitat Avoid focus on ecosystem function

Key Indicator Species Salmon Spawning and Ocean Counts, CA

GHG Emissions Methane emitted from altered biogeochemistry in reservoirs and downstream waterways compared to free- flowing river Approximately equal to amount from global aviation (4% of global emissions) (internationalrivers.org)

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 (March 22)

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

Changing Reservoir Releases (A) Pre- and (B) Post-Dam Sediment Fluxes Location Dist. below Dam (km) Sediment Reduction (mmt) Marble Canyon 2557 to 0.3 Upper Grand Canyon to 14

Changing Reservoir Releases 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

Changing Reservoir Releases General Pattern of Sand Bar Change (Badger Creek Rapids) Sand eroded from eddies Sand eroded by wind; not replaced by flood deposition

Changing Reservoir Releases Glen Canyon Dam Release Experiments 1.Reduce range of daily fluctuations (erosion control) 2.Spiked “floods” (rebuild high elevation sand bars) 3.Sustain low flows (trap fine sediment)

Changing Reservoir Releases November 2004 Sediment Mobilization Flows lost hydropower revenue ~ $1 million

Changing Reservoir Releases Release Regime Cost (lost hydro revenue) [$ Millions] Interim low fluctuating flows (per year) $36 Modified low fluctuating flows (per year) $ 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

Changing Reservoir Releases Glen Canyon Dam Postscript 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

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

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

Comparing Temperature Control Methods (Burgi, 1995)

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

Chinook (King) Salmon on the American River, CA at the Nimbus Hatchery Fish Ladder Fish Ladders

How Effective Are Fish Ladders? Fish Ladders

Task: calculate percent passage across 1-8 fish ladders (fishways) on the Columbia and Snake Rivers (GoogleSheet: Fish Ladders Fishway 8: XX% passage Fishway 7: XX% passage Fishway 6: XX% passage Fishway 5: XX% passage Fishway 4: XX% passage Fishway 3: XX% passage Fishway 2: XX% passage Fishway 1: XX% passage

Fish Screens

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

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

References Burgi, P.H. (1995). "The Evolving Role of Hydraulic Structures - From Development to Management of Water." Issues and Directions in Hydraulics - An Iowa Hydraulics Colloquium, Iowa City, Iowa, Hollinshead, S.P., and Lund, J.R. (2006). "Optimization of environmental water purchases with uncertainty." Water Resources Research, 42, W08403, Mostafa, M.G. (1957). "River-bed degradation below large capacity reservoirs." American Society of Civil Engineers Transactions, 122, 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, 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.