Conceptual Ecological Model of San Acacia Reach of Middle Rio Grande River – 2/13/07 1 st DraftIbis Ecosystem Associates, Inc.

Diversion & Regulationof Stream Water

Structural Alteration &Development of Floodplain

Discharge of ContaminantsInto Stream System

Degraded Water Quality

Introduction and Spread ofNon-native Vegetation

River Channel Fragmentation

FloodplainLoss &

Fragmentation

High Temperature,High pH, Low DO

Barrier toUpstream

Movement ofSilveryMinnow

Severe FlowReductions

Loss of Natural VariabilityIn Annual & Seasonal

Discharge Pattern& Hydrograph

Hydrologic Degradation of River Channel Habitat:•Reduced Magnitude & Duration of Spring Peak Flows•Reduced Flowing Water With Low-Moderate Currents•Narrowing of River Channel•Reduced Over-bank Flooding in Spring•Dewatering of River Channel & Formation of Isolated Pools•Reduced Sand and Silt Substrates•Reduced Eddies From Debris Piles, Pools, & Backwaters

Saltcedar

Proliferation

Loss of PersistentMoisture Levels &Wetland HabitatsIn Riparian Areas

Increased FireFrequency &Intensity In

Riparian Areas

Loss of Dynamic CyclesOf

Riparian Habitat Succession

Loss ofConnectivity

BetweenFloodplain &Native Desert

Habitat

River Channel Habitat Quality:•Perennially Flowing River With Peak Spring Flows and Over-bank Flooding•Aggrading River With Shifting Sand Substrate•Sinuous, Braided River That Freely Migrates Across Floodplain, Producing Eddies From Debris Piles, Pools, & Backwaters

Floodplain Habitat Quality:•Persistent Moisture Levels & Wetland Habitats in Riparian Areas•Highly Variable Mosaic of Ephemeral Wetland Habitats, Supporting Willow & Cottonwood Stands Adjacent to Wetland Areas•Unfragmented Landscape of Wide Lateral Extent, With Riparian Habitat Connected to Native Desert Habitat

Rio GrandeSilveryMinnow

SouthwesternWillow

Flycatcher*

FloodplainLowered

Water Table

Drivers

Stressors

Effects

Attributes * Impact of cowbird on flycatcher nesting to be covered in text.

Conceptual Ecological Model of San Acacia Reach of Middle Rio Grande River – 10/07 Draft

Diversion & Regulationof Stream Water

Structural Alteration &Development of Floodplain

Introduction & Spread Non-Native Vegetation

RiverChannel

Fragmentation

FloodplainLoss &

Fragmentation

Barrier toUpstream

Movement ofSilveryMinnow

SevereFlow

Reductions

Loss of Natural VariabilityIn Annual & Seasonal

Discharge Pattern& Hydrograph

Hydrologic Degradation of River Channel:•Reduced Magnitude & Duration of Spring Peak Flows•Reduced Channel Avulsion During Spring Peak Flows•Reduced Over-bank Flooding During Spring Peak Flows•Reduced Flowing Water With Low-Moderate Currents•Narrowing of River Channel•Dewatering of River Channel & Formation of Isolated Pools•Reduced Sand and Silt Substrates•Reduced Eddies From Debris Piles, Pools, & Backwaters

Loss of PersistentMoisture Levels

& WetlandsIn Riparian Areas

Increased FireFrequency &Intensity In

Riparian Areas

Loss of Dynamic Cycles OfRiparian Plant Succession,

Producing Dense Even-agedStands, & Resulting In Loss

Of Habitat Mosaic

Loss ofConnectivity

BetweenFloodplain &Native Desert

River Channel Quality:•Natural Variability In River Flow Dynamics, With Peak Spring Flows, Avulsion, & Over-bank Flooding•Aggrading River With Shifting Sand Substrate•Sinuous, Braided River That Freely Migrates Across Floodplain, Producing Eddies From Debris Piles, Pools, & Backwaters

Floodplain Quality:•Persistent Moisture Levels in Wetlands & Riparian Areas•Highly Variable Mosaic of Ephemeral Floodplain Communities, Supporting Willow & Cottonwood Stands Adjacent to Wetland Areas•Non-fragmented Landscape of Wide Lateral Extent, With Floodplain Connected to Native Desert

Rio GrandeSilveryMinnow

SouthwesternWillow

Flycatcher

FloodplainLowered

Water Table

Drivers

Stressors

Effects

Attributes

Altered Physical &Chemical CharacteristicsOf River Water:•Reduced Sediment Load•Reduced Temperature•Increased Ammonia

Aquatic Communities:•Viable Populations of Key Indicator Groups of Aquatic Fauna•Aquatic Fauna Community Diversity

Marsh Communities:•Creation of New Marshes•Persistence of Established Marshes

Cottonwood – WillowCommunities:•Seedling Recruitment•Persistence of Established Communities

Conceptual Ecological Model of Working HypothesesAquatic Communities

San Acacia Reach of Middle Rio Grande River10/07 Draft

Recruitment-Level Flow Events•April-June3,000 – 4,000 cfs2-Week Duration3-Year Frequency

Hydrologic Connectivity•River Channel to Floodplain•Surface Water to Groundwater

Episodic Flow Events

Channel Avulsion & Scouring

BackwaterNursery Habitat

Viable Populations of Key IndicatorGroups of Aquatic Fauna

(Including Rio Grande Silvery Minnow)

Aquatic FaunaCommunity Diversity

Over-bankFlow

River & FloodplainManagement

Hydrologic &Geomorphic Effects

PerformanceMeasures

AquaticCommunityAttributes

Persistent PoolsAs Aquatic RefugiaDuring Dry Periods

Bank-full Flow&

Dynamic In-Channel Morphology

Recruitment To Adult StageSurvivorship By Age Class

Population Geometric Growth Curves

Diverse Sediment SizeDistribution &

Shifting Sand Substrate

Prevention of StrandingWith

Water Level Recession

Aquatic Habitat Heterogeneity:•Multi-Threaded Channel•Dynamic/Avulsive Channel•Channel Width/Depth Ratio•Backwaters•Woody Debris

Conceptual Ecological Model of Working HypothesesMarsh Communities

San Acacia Reach of Middle Rio Grande River10/07 Draft

Maintenance-Level Flow Events3-Year Frequency

Hydrologic Connectivity•River Channel to Floodplain•Surface Water to Groundwater

Episodic Flow Events•7,000 – 10,000 cfs•1-week Duration•10-Year Frequency

Channel Avulsion & Scouring

Bank-full Flow&

Dynamic In-Channel Morphology

Water Level Fluctuation•Minimum 3-Foot Fluctuation•< 3-Year Frequency

Marsh Community Maintenance:•Marshes Sustained by Surface Water & Groundwater•Marshes Sustained Entirely By Groundwater

Marsh Community Creation:•Active Channel Marsh Communities•Marshes Sustained by Surface Water & Groundwater•Marshes Sustained Entirely By Groundwater

Over-bankFlow

River & FloodplainManagement

Hydrologic &Geomorphic Effects

PerformanceMeasures

Marsh CommunityAttributes

Site Preparation & Management•Removal of Non-Native Vegetation•Fire Management•Other

GroundwaterLevel

Longevity and SuccessionOf Established Marshes

Marsh Community Maintenance:•Active Channel Marshes

Frequency, Location, & Spatial Coverageof Newly Created Marshes

Spatial Coverage ofEach Marsh Community Type

Conceptual Ecological Model of Working HypothesesCottonwood - Willow Communities

San Acacia Reach of Middle Rio Grande River10/07 Draft

Recruitment-Level Flow Events< 5-Year Frequency

Hydrologic Connectivity•River Channel to Floodplain•Surface Water to Groundwater

Episodic Flow Events

Channel Avulsion & Scouring

Water Level Fluctuation•Soil Wetting May-June•Maximum Groundwater Recession Rate of 2 – 4 cm/day

Persistence of EstablishedCottonwood & Willow

Communities

Successful RecruitmentOf Cottonwood &Willow Seedlings

Over-bankFlow

River & FloodplainManagement

Hydrologic &Geomorphic Effects

PerformanceMeasures

Cottonwood/WillowCommunityAttributes

Site Preparation & Management•Removal of Non-Native Vegetation•Fire Management•Other

Groundwater Level:Depth To Groundwater

Of 3 – 6 Feet

Frequency, Location, & Spatial CoverageOf Seedling Recruitment Of

Cottonwood and Willow

Location, Spatial Coverage, & LongevityOf Established Cottonwood & Willow

Communities

Creation of Scoured HabitatFor Seedling Recruitment,

Formation of Bars and IslandsFor Willow Establishment