Anthropogenic fragmentation severely limits movement Very large dams globally (B. Lehner, WWF) "GWSP Digital Water Atlas (2008). Map 25: River Fragmentation by Dams (V1.0). Available online at http://atlas.gwsp.org." Global fragmentation of large river basins Snake River dams and decline of Chinook salmon Dams on the Columbia River >75,000 dams 2+m high in U.S.

Streamflow regime: a “master” variable Varies over time - Day to day, week to week, year to year - Inter-annual variation of wet and dry years Varies along a river’s length Varies regionally with climate (Poff et al., 1997)

Streams and rivers differ in natural flow regimes Key components that characterize a full flow regime and that have ecological importance: Magnitude of discharge – amount Frequency of events Duration Timing - regularity and seasonal predictability Rate of change

Streams and rivers differ in natural flow regimes

Hydrogeography of natural flow regimes in U.S. Offers context for considering regional variation in impacts of climate change on pattern of natural (background) variation Poff & Ward (1989, 1990), Poff (1996).

Key science challenges? Develop a better scientific understanding of geographically-distributed risk to FW species and ecosystems (research issue) Develop science-based conservation “priorities” based on regional risk and likelihood of successful interventions Develop models that capture fine scale hydro-geomorphic and ecological grain (river segment scale?) and in a river network context. Different from terrestrial systems in this regard! Develop better methods for “quantifying” ecosystem goods and services and the long-term ecological costs and benefits of different management options New paradigm for water management that proactively accommodates ecosystem needs at local to regional scales in order to build ecological resilience in the face of rapid climate change.

Natural flow regime and ecological processes Specifics of magnitude, frequency, duration, timing and rate-of-change dictate ecological processes and outcomes. Bunn & Arthington. 2002. Environmental Management

General philosophy of restoring flow-altered systems Quantify changes in disturbance/flow regime Before vs. After Indicators of Hydrologic Alteration (Richter et al. 1996; Mathews & Richter 2007) Many other metrics (Olden & Poff 2003) Natural Regulated Re-regulated Aim to restore (re-regulate) components of natural flow regime that provide key ecological functions Stanford et al., 1996, The normative river concept, Regulated Rivers.

International Concern and Consensus http://www.watercentre.org/news/brisdec

Freshwater biodiversity is at disproportionate risk of extinction Vulnerable and Imperiled Species Projected extinction rates Freshwaters: 3.7% per decade Terrestrial vertebrates: 0.8% per decade (Ricciardi & Rasmussen 1999) (L. Master, TNC)

Ecosystem Goods, Services, Amenities (Poff et al. 2002)

What are the major threats to FW Ecosystems? Many interacting factors contribute to global biodiversity crisis and FW ecosystem degradation. Over- Exploitation Water Pollution Habitat Degradation Species Invasions Flow Modification Fig. 1. The five major threat categories and their established or potential interactive impacts on freshwater biodiversity. Climate change will exacerbate these continuing threats. (Dudgeon et al. 2006)

Extensive wetland draining in United States since the 1800s. Current human management practices have altered ecosystem goods and services Extensive wetland draining in United States since the 1800s. Extensive fragmentation by >75,000 dams 2+ m high in U.S.

A key point: Is this possible during climate change? Functional, self-sustaining ecosystems are needed to provide ecosystem goods & services and to maintain native biodiversity. Is this possible during climate change? Need to know how FW ecosystems function and how sensitive function is to climate change

Pressing Conservation Issue Define the water needs of freshwater ecosystems to legitimize their protection and restoration. (Baron, Poff et al., 2002, Ecol. Appl.) (Poff et al., 2003, Frontiers Ecol. Environ.) Key Question: How do we develop guidelines for flow needs in unstudied streams?

Scientific approach of ELOHA - Classify streams in a region according to natural flow regimes (and subclassify according to major geomorphic setting). - Define natural range of hydrologic variation and ecological variation for each stream class. - Put flow-impaired streams into one of the natural flow regime classes. - Establish ecological responses to flow alteration for each class. - Test with existing field data or monitoring data. - Refine models. - Continue… Arthington et al., 2006, Ecol. Appl. Complete presentation available at: http://rydberg.biology.colostate.edu/~poff/fw400.pdf Poff publications referenced in lecture are at: http://rydberg.biology.colostate.edu/~poff/

A framework for developing regional environmental flow standards The Ecological Limits of Hydrologic Alteration (ELOHA) A framework for developing regional environmental flow standards LeRoy Poff, CSU Brian Richter, TNC Angela Arthington, ARI (Australia) Stuart Bunn, ARI (Australia) Robert Naiman, UW Eloise Kendy, TNC Mike Acreman, CEH (UK) Colin Apse, TNC Brian Bledsoe, CSU Mary Freeman, USGS James Henriksen, USGS Robert Jacobson, USGS Jonathan Kennen, USGS David Merritt, USFS Jay O’Keeffe, UNESCO-IHE (Netherlands) Julian Olden, UW Kevin Rogers, U. Witwatersrand (SA) Rebecca Tharme, IWMI (Sri Lanka) Andrew Warner, TNC

SCIENTIFIC PROCESS SOCIAL PROCESS Step 1. Hydrologic Foundation Monitoring Acceptable Ecological Conditions Societal Values and Management Needs Implementation SOCIAL PROCESS Adaptive Adjustments Flow Alteration-Ecological Response Relationships by River Type Stream Hydrologic Classification Degree of Hydrologic Alteration Hydrologic Alteration Baseline Hydrographs Developed Ecological Data and Indices Environmental Flow Standards Hydrologic Model and Stream Gauges Flow - Ecology Hypotheses Geomorphic Stratification Step 4. Flow-Ecology Relationships Step 3. Flow Alteration Step 2. Stream Classification

Pressing Conservation Issue Define the water needs of freshwater ecosystems to legitimize their protection and restoration. (Baron, Poff et al., 2002, Ecol. Appl.) (Poff et al., 2003, Frontiers Ecol. Environ.) Key Question: How do we develop guidelines for flow needs in unstudied streams?

Scientific approach of ELOHA - Classify streams in a region according to natural flow regimes (and subclassify according to major geomorphic setting). - Define natural range of hydrologic variation and ecological variation for each stream class. - Put flow-impaired streams into one of the natural flow regime classes. - Establish ecological responses to flow alteration for each class. - Test with existing field data or monitoring data. - Refine models. - Continue… Arthington et al., 2006, Ecol. Appl. Complete presentation available at: http://rydberg.biology.colostate.edu/~poff/fw400.pdf Poff publications referenced in lecture are at: http://rydberg.biology.colostate.edu/~poff/

http://www.nature.org/initiatives/freshwater/strategies/flows.html

http://water.epa.gov/polwaste/nps/watershed/index.cfm

http://conserveonline.org/workspaces/eloha/documents/template-kyle