HomeMy WebLinkAboutCOUNCIL - AGENDA ITEM - 03/27/2012 - POUDRE RIVER ECOSYSTEM RESPONSE MODEL (STAFF: STOKDATE: March 27, 2012
STAFF: John Stokes
Jennifer Shanahan
Pre-taped staff presentation: available
at fcgov.com/clerk/agendas.php
WORK SESSION ITEM
FORT COLLINS CITY COUNCIL
SUBJECT FOR DISCUSSION
Poudre River Ecosystem Response Model.
EXECUTIVE SUMMARY
There are five bottom-line elements described in this Agenda Item Summary (AIS).
1. The Poudre River Ecosystem Response Model (ERM) is approximately 75% completed. It
will be finished by summer. This AIS provides a status report on progress to date and should
not be regarded as a definitive description of the model.
2. The model is a decision support tool that can help compare different scenarios and potential
outcomes for the river ecosystem. It is a probability based model; it does not predict precise
outcomes but provides decision makers with coarse level estimates of future ecological
conditions.
3. An initial model “run” has been completed for so-called Scenario I, which is a representation
of the current operating and environmental conditions of the Poudre River projected forward
for 50 years. This particular model run indicates that the state of the five model indicators
used in the model (riparian vegetation, native fish, brown trout, aquatic invertebrates, algae)
is likely to change in a way that represents a decline from current conditions.
4. While there has been much focus on instream flows as a key driver of ecological health and
resilience; the intentional channelization and hardening of the river’s banks also play a major
role.
5. The model will provide insights as to how desirable river attributes could be supported.
The purpose of this work session is twofold: (1) to provide Council with an early overview of the
ERM; and, (2) to respond to any Council questions or concerns.
Council and the community have expressed support for, and interest in, a healthy Poudre River. The
purpose of the Ecosystem Response Model is to inform that desire with a scientific understanding.
The model represents one element of a series of endeavors that are based on Council direction and
designed to help achieve the community’s goals. Other elements include direction to the Natural
Areas Department Director to allocate at least half of his time to the Poudre River, as well as a
variety of restoration and rehabilitation projects.
While the Poudre River provides many services, such as drinking water, local food production, and
support for the City’s valued commercial enterprises, the project described herein focuses
March 27, 2012 Page 2
specifically on the river ecosystem. The ERM described in this AIS is an attempt to provide an
understanding of the Poudre River that is informed by both data analysis and expert judgment. This
understanding, in turn, should help the community make informed decisions that are more likely to
achieve the aspirations described in Plan Fort Collins for a healthy, resilient Poudre River.
The ERM will yield a decision-guidance tool and help us deepen our understanding of how the river
works as an integrated ecological system. At a practical level, the model will provide a coarse-scale
evaluation of the potential consequences of specific proposals, including proposed water supply and
storage projects. It also should help us understand what mitigation measures would be most
effective if those projects are implemented.
The initial version of the ERM will be complete by summer. While the initial version of the model
will provide indications of how the river may respond under certain flow and channel
configurations, it has the potential to be a more powerful application tool. Staff believes that
refining the ERM over time is desirable and we will include an offer for that purpose in the 2013/14
budget cycle.
GENERAL DIRECTION SOUGHT AND SPECIFIC QUESTIONS TO BE ANSWERED
1. Does Council have any questions about the model?
2. Does Council have any suggestions or concerns regarding the model or how it will be used?
BACKGROUND / DISCUSSION
1. Introduction
City staff has been collaborating with a team of scientists from Colorado State University, The
Nature Conservancy, and the United States Forest Service to develop an ecological model of the
Poudre River. The model integrates multiple interacting factors which are intended to represent the
interdependent and complex nature of the river. This approach distinguishes the model from more
common methods that use one or two causal factors in evaluating a biological outcome in response
to some environmental driver. The model incorporates available scientific data and expert
judgment, allowing for a multi-factor analysis despite limited data for some indicators.
The model was developed with the intent to be broad and comprehensive with regard to the potential
factors that may affect river ecology, and to provide coarse level probability-based projections of
future ecological states of the river, given long-term changes in the Poudre River flow regime. The
model cannot be used to project outcomes that are highly detailed. Rather, the ERM is intended to
provide insight into probable trajectories of how the river might change in the future. It also should
be able to highlight elements within the ecosystem that are most important in causing future change
and those that are most at risk from change.
March 27, 2012 Page 3
This project is 75% complete and thus only preliminary findings and themes are available. Results
and associated documentation will be available this summer after model testing (verification and
validation), refinement and a fully developed set of model runs have been completed.
The input of the model is a specific flow scenario (a pattern of river flows over many years) and
management actions that ultimately generates outputs of channel structure and the conditions of five
biological indicators:
• riparian vegetation,
• native fish,
• coldwater sport fish (as measured by brown trout),
• aquatic invertebrates, and
•algae
These five biological indicators were selected as desired model output because collectively they can
provide an indication of overall river health. Each of the five biological indicators represents the
summation and interaction of a number of physical and biological system functions that are known
to be sensitive to river flows. Given the model is still undergoing development and validation it is
premature to show comprehensive or detailed results. There are, however, trends emerging about
the overall system and its components.
2. Discussion Points and Preliminary Results
• What is a healthy and resilient Poudre River?
In the discipline of ecological science, the native condition usually represents the healthiest and most
resilient set of conditions. However, returning the Poudre River to the native condition is not
possible given encroaching urbanization and the existing system of water administration and
ownership. Therefore, a common challenge to contemporary natural resource managers is to clearly
define core elements of a desirable, realistic, achievable condition and the environmental processes
that sustain them, while also identifying thresholds of degradation that are unacceptable to the
community. Another task is to identify new innovative solutions and unique landscape management
opportunities.
• The model reflects the importance of dynamic interactions
The model supports the fundamental premise that the character of the Poudre primarily is dependent
on flow patterns and secondarily dependent on its physical structure, i.e., the degree of confinement
(channelization, armoring, and encroachment) that limits the river’s ability to maintain diverse
habitats. The dynamic interaction between flow patterns and the level of confinement determines
habitat potential in the river corridor.
• What we see may not be what we’ve got
The impact of the current pattern of operations, diversions, and flows (Scenario 1) has likely not yet
completely manifested itself on the Poudre River ecosystem. For example, the existing off-channel
flats of mature cottonwood forests are relicts of previous conditions when the river was still
connected with its floodplain. While the forests respond over long time spans (50-100 years),
March 27, 2012 Page 4
aquatic wildlife is expected to respond to recent vegetation encroachment and the increasingly
armored riverbed over a much shorter timeframe.
• Cause for concern
Similar to the situation in many urban rivers, several ecological indicators in the urban reach of the
Poudre River have substantially changed from pre-development condition due to flow reductions,
channelization, and hardening of the river’s banks. The ERM suggests that even under the current
flow regime:
• The corridor of riparian vegetation and forest along the river is likely to be
narrower. If no further mechanical restoration of the river bank topography
occurs, then opportunities and available habitat for wetland and native
riverside vegetation to regenerate are minimal in the upper reaches and
moderate in some of the less developed downstream reaches.
• Further reductions in abundance and diversity of aquatic invertebrates
(insects) are possible, and more tolerant species such as worms and midges
may predominate in the future.
• Both trout and native fish populations could decline, and both populations
could become more vulnerable and in danger of collapse.
While these results are preliminary, it is possible that ongoing changes to the river ecosystem (based
on current operations) could make it difficult to meet the community’s goals for the Poudre River
as set forth in Plan Fort Collins and other policies. This makes it all the more important to develop
a common understanding of the factors driving change and how the community can implement
actions to drive change in a more positive direction with respect to ecological values.
• The nature of the problem - there is no silver bullet
Because different pieces of the system are inextricably linked, preliminary results from the ERM
suggest that no one action alone is likely to impact the degree or pace of potential change in the
biological indicators. Each indicator is impacted by multiple factors; increasing the function in one
factor often exposes the negative impact of another factor. For example, adequate flow in winter
is crucial for a healthy trout fishery, but increased winter flow only does so much if the quality of
the habitat in the river is poor (e.g., clogged with algae or silt) due to lack of scouring by high flows.
As a result, actions to move toward a healthy and resilient river will need to be multi-faceted and
integrated.
• Opportunities for effective management actions
Preliminary work with the ERM shows that there may be combinations of management actions that
can slow or prevent further change in some or all of the biological indicators. Depending on the
desired state of the ecosystem, these actions could include provision of minimum flow in winter
and/or summer; periodic high flow events; restoration of habitat; and/or modification of stabilization
structures along the river banks in safe locations.
March 27, 2012 Page 5
• A new era in natural resource management
The combination of altered flows, urbanization, and anticipation of decreasing flows in the future,
has put this reach of the Poudre on a new trajectory. While challenging, this new trajectory is not
without opportunities. A good example of a new and positive process is the extensive establishment
of plains cottonwoods along restored gravel pond shorelines that we see today. Fluctuating water
levels as associated with spring rise in the river (or wet conditions due to spring rains) on gently
sloping shorelines mimic conditions required by cottonwoods for natural seedling establishment.
These populations of plains cottonwoods provide habitat and a future seed source that could enable
this keystone species to remain co-dominant within the floodplain (even if not directly along the
riverbanks) if such conditions were reestablished in strategic locations along the river corridor.
Contemporary natural resource managers and their communities have a uniquely challenging but
interesting task of examining urban ecosystems through an innovative lens to identify and support
processes that sustain ecosystem functions such as: clean water, abundant wildlife, and healthy
riparian forests while the resource is at the same time being used to provide dependable water
supplies to the community.
3. Additional Background
• Why develop this model?
Riverine scientists around the world have published numerous papers calling for collaborative
science-based processes to help resolve regional water demands while maintaining ecological
integrity of river ecosystems. The City of Fort Collins initiated this collaborative modeling project
to: (1) improve overall understanding of the river; and, (2) help estimate both a flow regime and
management actions necessary for maintaining a healthy river ecosystem as envisioned by the
community. While there is some specific ecological knowledge about particular aspects of the
Poudre River, a quantitative and integrated characterization is lacking. Furthermore, this is a
controversial and complicated subject and it is difficult to derive agreement among stakeholders as
to what the river needs from an ecological perspective. Thus, the ERM is intended to model the
interrelated factors pertaining to the river ecosystem and provide a coarse-level indicator basis from
which to engage in internal and external discussions.
• The team
The modeling team represents some of the best expertise in each sub-discipline of river science. The
team primarily consists of research scientists along with one consultant who has built the model for
us. Collectively this group has over 370 peer reviewed publications and many of these publications
have contributed to cross-disciplinary and applied river science.
• Mark Lorie: Independent consultant specializing in water resources planning
• Dr. Brian Bledsoe: Hydrologist, Department of Civil and Environmental
Engineering and Graduate Degree Program in Ecology, CSU
• Dr. LeRoy Poff: Aquatic Biologist, Department of Biology and Director of
the Graduate Degree Program in Ecology, CSU
• Dr. John Sanderson: Co-director for Colorado’s Center of Science and
Strategy, Freshwater Biologist, The Nature Conservancy
March 27, 2012 Page 6
• Dr. Boris Kondratieff: Entomologist in the Dept of Bioagricultural Sciences
and Pest Management, CSU
• Dr. Kevin Bestgen: Director and Research Scientist, Larval Fish Laboratory,
Department of Fishery and Wildlife Biology, CSU
• Dr. David Merritt: Riparian Ecologist for the Stream Team United States
Forest Service
Additionally, Dr. Gregor Auble, research ecologist with USGS, has provided technical assistance
to the group regarding riparian vegetation modeling.
• Scope of the project
This project focuses on the urban reach of the Poudre River, specifically from Overland Trail Road
to Interstate-25. The model was developed under a 30-50 year planning horizon.
• The natural history of the Poudre River
Prior to the agricultural and urban development of more than 160 years (referred to herein as
“native” conditions), Colorado’s rivers and the species within them evolved with high flows driven
by the spring snow melt. The extremely high water levels each spring caused widespread
disturbance, scour, deposition, flooding and consequent movement of the river channel back and
forth across the floodplain. Native wildlife and plants in the river ecosystem are uniquely adapted
to and dependent on these periodic patterns of disturbance while also surviving the extreme dry
conditions of fall and winter flows. Due to this disturbance the native Poudre River was highly
sinuous bordered by a ribbon of riparian forest that thinned out as it travelled east beyond Fort
Collins. The forest itself was highly variable in age, topography and width. The life history events
of the aquatic life, especially the fish and invertebrates closely followed these seasonal flows.
These patterns of disturbance regime varied among years in terms of the magnitude of high and low
flows. Thus, the river corridor was heterogeneous and the abundance and reproduction of aquatic
and riparian species varied from year to year. In wet years high flows accessed the floodplain re-
worked the channel and created complex off-channel habitats that supported aquatic and riparian
species. Reproduction among riparian species would vary from year to year, depending on the
intensity and spatial (lateral) extent of floodplain inundation. High flows could cause some
immediate mortality of aquatic species, but the complex channel structure created and maintained
by high flows (deep scour pools, off-channel habitats) provided refuges that ensured survival and
rapid recovery in the rejuvenated in-channel habitat (e.g., cleansed beds for insects and spawning
native fishes).
The stretch of the Poudre River running through the City is characterized as a transitional zone
because it is situated between the fast flowing, steep, cold montane river coming out of the
mountains, and the slow, winding, warm river of the eastern plains of Colorado. The composition
of the vegetation and wildlife communities was representative of this transitional zone. For example,
upper reaches of the river were nearly entirely dominated by narrowleaf cottonwood whereas
downstream reaches were dominated by plains cottonwood. A similar shift occurred in shrubs and
herbaceous plant communities; as well as in the aquatic species such as native fish and benthic
invertebrates, with montane species dominating the upper reaches and more warm adapted species
in the lower reaches. (See Attachment 1)
March 27, 2012 Page 7
• The contemporary urban Poudre River
A common local saying is that “the Poudre River is the hardest working river in Colorado.” In
addition to the numerous diversions from the river, the urbanization surrounding this reach of the
Poudre River has constrained the extent to which the river can move which, in turn, has limited the
available habitat for both plants and aquatic animals. Given these two fundamental limitations, goal
setting for a healthy, resilient river must combine inspiration with pragmatism. For example,
management actions could allow the river system to sustain values such as diverse native vegetation,
albeit within a narrower corridor.
4. The Model
The team elected to use a Bayesian Network (BN), also known as a belief network or probabilistic
network, to develop the Poudre River ERM. A BN is based on a simple influence diagram, in which
important variables in a given system are represented by nodes, and arrows connecting the nodes
indicate a causal relationship between those variables. (See Attachment II, figure 1) Several distinct
outcomes, or states, are defined for each variable. For example, for a variable representing the
health of the fishery, the states might represent ranges of population density of the fish species
within the water body (specific examples for the Poudre ERM are given in subsequent section). The
causal relationships are described by probabilities of each variable ending up in one of its potential
states given the states of the variables that impact it (shown by the arrows). The output of a BN
consists of probabilities of the outcome variables ending up in one of their states. Inputs to a BN
can be varied to model the impact of different scenarios on the probabilities of outcomes.
For purposes of this project, the BN approach has several advantages. First, it uses an established
methodology for integrating across various ecosystem functions that are typically modeled as
independent and non-interacting. It is intended to capture most or all of the important functions in
a system, which allows for a systematic, integrated evaluation, albeit at a coarse level, of cause and
effect among different elements of the ecosystem. Second, a BN can incorporate different and
distinct sources of data such as output from other models, databases, as well as expert judgment.
Third, a BN is explicit about uncertainty because causal relationships between variables are
described probabilistically and the outcomes are described in terms of their probabilities. Finally,
this kind of model is very flexible so it can be used to test various kinds of scenarios and the
sensitivity of outcomes to individual factors. For example, the model will allow us to test how
different kinds of restoration projects might function under different flow conditions.
This approach also has some disadvantages. As noted above, the model is built with a mixture of
hard data and expert judgment. Using expert judgment means that the model will provide results
in the absence of data specific to the Poudre, but those results will be partially based on scientific
literature and knowledge of comparable systems. This means the model must be rigorously tested
and the results interpreted with appropriate caution. As with any simplified representation of a
complex system, there is model uncertainty. Additionally, the ERM is a coarse level model that
provides probabilities of what might happen as opposed to a determined outcome.
March 27, 2012 Page 8
5. Model Input and Model Output
• Flow scenarios (model input)
Most of the primary inputs to the model are derived from river flow scenarios. A flow scenario is
a dataset that describes patterns of flow over time at various points on the river. For this initial
phase of the work the scenarios reflect two or more possible water management scenarios and some
plausible climate change scenarios. The scenarios are based on data from Fort Collins Utilities, the
Northern Colorado Water Conservancy District and a Federal consortium of climate research.
The flow scenarios used for this work are meant to provide a plausible range of possible future
hydrologic conditions on the river in order to (1) test how well the model describes potential changes
in the ecosystem; and, (2) begin to investigate risks and vulnerabilities to the ecosystem. The model
can incorporate new scenarios as new data and information become available (e.g., data that will
become available when the Army Corps finishes its environmental analyses of the Northern
Integrated Supply Project and the Halligan Seaman projects).
One key scenario is defined below and from this scenario we have preliminary results and have
observed emerging themes. The team plans to run additional scenarios once model testing has been
completed, including future diversions and proposed reservoirs, several plausible climate change
scenarios, reconstructed native flows, and historic flows.
Scenario 1: Status Quo Operations Continued – this scenario takes the diversions and reservoir
operations that are in place today and applies those diversions and operations to the available
historic record of hydrology. It is as though today’s water use and management actions were held
static for many years. When applied in the Poudre ERM, this scenario provides an indication of how
the river might change if the status quo were held constant several decades into the future.
Biological indicators (model output)
As previously stated the model is structured to provide output for five biological indicators this team
has identified as important; riparian vegetation, native fish, sport fishery (as measured by brown
trout) aquatic insects, and algae. These five biological indicators were selected as desired model
output because collectively they can provide us with an indication of overall river health. While
terrestrial (land-based) wildlife in the river corridor is clearly important it is only indirectly linked
to flow and therefore it was not included in this phase of the project.
For each indicator, the team defined several possible states of health representing a range of
conditions. The categorical sets of conditions represent current conditions and improvements or
degradation from the current condition. An example is given in the table below.
March 27, 2012 Page 9
Table 1: ERM States for Native Fish Population
State Definition
- -
Low diversity (4 or fewer taxa in warmwater streams) and
abundance (<100 individuals total) in standard sampling effort,
single life stages for most species
-
Low diversity (6 or fewer taxa in warmwater streams) or
abundance (<100 indivduals total) in a standard sampling effort,
single life stage for many species
0
Moderate diversity (7-12 taxa in warmwater streams) and
abundance (100-1000 individuals total in standard sampling
effort), 2 or more life stages per species
+ High diversity (>12 taxa in warmwater streams) and high
abundance (>1000 individuals total), multiple life stages
As described above, the output of the ERM is the probability of ending up in the various states for
each biological indicator. These probabilities will vary across different scenarios. A sample output
for Native Fish in the reach between Shields and College is shown in Attachment II figure 2.
This output of probabilities is then read similar to a weather report. Under Status Quo Operations
Continued, there is a 21% chance that the native fish populations will be in the same condition as
they are today.
6. Model Completion
The goal for completion of the modeling includes the following steps:
1. Model testing (verification and validation), refinement, model runs, and
interpretation
2. Run additional flow scenarios through additional reaches within the city
3. Share the model with the public, potentially thru an open house format in fall
of 2012
ATTACHMENTS
1. Aerial photos of Poudre River
2. Figure 1: Simple example of BN, based on some elements of the Poudre River ERM
Figure 2: Example of ERM Output for Native Fish populations
3. Powerpoint presentation
ATTACHMENT I
These two aerial photos of the Poudre River demonstrate how urbanization has arrested natural processes
associated with channel movement. The photo below was taken in 1937 includes the area between
Overland and Taft. In this image cottonwood forests of various ages have establish along the former paths
of the river and along the point bars (the inside of each curve).
The image on the left shows the Poudre River from College
Avenue through downtown as it travels under Linden and Lincoln.
The river is not able to move back and forth due to multiple
bridges, buildings, rip rap, and levees. In response to this
confinement, the riparian forest has narrowed so that the
cottonwoods are limited to the zone immediate adjacent to the
channel. On the right side one can see the old path of the river
where a remnant oxbow, still populated with cottonwoods tells the
story of the river’s meandering past.
ATTACHMENT 2
Figure 2: Example of ERM Output for Native Fish populations; definitions of the states
are provided in the table included in the Agenda Item Summary.
1
Poudre Poudre River River
Ecological Ecological Response Response Model Model
John Stokes, Poudre River Sustainability Guru
Dr. Brian Bledsoe, Dept. of Civil and Environmental
Engineering, Colorado State University
Council Work Session March 27th, 2012
2
Overview Overview
Last July staff shared with
Council a plan to initiate a
science-based process to
develop an ecological model of
the Poudre River thru town.
The project, called the Poudre
River Ecological Response
Model (ERM), is 75% complete.
The goals for today are to
update you on the ERM and to
respond to questions/concerns.
3
General General Direction Direction Sought/Sought/Specific Specific
Questions Questions
1. Does Council have any questions about the
model?
2. Does Council have any suggestions or concerns
regarding the model or how it will be used?
3. Would Council like staff to return and present
results of the final model (which we anticipate will
be complete by summer) or would Council prefer
to receive a copy of the report?
4
The The team team
• Dr. Brian Bledsoe, CSU, Environmental Engineer
• Dr. LeRoy Poff, CSU, Aquatic Ecologist
• Dr. Kevin Betsgen, CSU, Fisheries Biologist
• Dr. Boris Kondratieff, CSU, Entomologist
• Dr. David Merritt, USFS, Stream Team - Riparian Ecologist
• Dr. John Sanderson, The Nature Conservancy, Freshwater Ecologist
• Also Dr. Gregor Auble, research ecologist with USGS, has provided
technical assistance to the group regarding riparian vegetation modeling.
• Mark Lorie, consultant in water resource planning
• Staff: John Stokes, Natural Areas Department Director
Jen Shanahan, Environmental Planner
5
Why Why Create Create an an ERM? ERM?
• To create an integrated science-based understanding of
Poudre River ecology and to improve our overall
understanding of the Poudre River as system
• To provide decision makers and the community with a
decision and planning tool intended to help inform/guide
management efforts to achieve the community’s aspirations
for a healthy and resilient Poudre River
• The ERM is one effort among many to achieve the
community’s aspirations for a healthy, resilient Poudre
6
Scope Scope of of the the Project Project
• The project examines the urban reach of the
Poudre from Overland Trail Road to I-25
7
Key Key Points Points
• The Ecosystem Response Model (ERM) is approximately
75% complete. It will be finished by summer. This
presntation is a status report on progress to date and
should not be regarded as a definitive description of the
model.
• The model is a decision support tool that can help compare
different scenarios and potential outcomes the river
ecosytem. It is a probability based model; it does not
predict precise outcomes but provides decision makers
with coarse level estimates of future ecological conditions.
8
Key Key Points Points
• An initial model “run” has been completed for so-called
Scenario I, which is a representation of the current operating
and environmental conditions of the Poudre River projected
forward for 50 years. This particular model run indicates
that the state of the five model indicators (riparian
vegetation, native fish, brown trout, aquatic invertebrates,
algae) is likely to change in a way that represents a decline
from current conditions.
9
ERM ERM –– A A Bayesian Bayesian Network Network
Input: Flow scenarios (for now)
Later: Climate change, management approaches
Allows us to combine data and multiple sub-models
with expert judgment
Output: Condition of five Biological Indicators
Provides us with probabilities of outcomes. Like a
weather report: “There is a 20% chance of having
an excellent trout population”
10
Why Why a a Bayesian Bayesian Network Network model? model?
• Provides an established methodology for modeling the
river as a whole, integrated system
• Brings together different types of sub-models into a
unified framework
• Explicit about uncertainty – describes potential outcomes
in terms of probabilities
• Flexibility – can test many kinds of scenarios and
examine sensitivity to individual factors
11
Where Where
in in the the
watershed watershed
does does the the
model model
focus? focus?
Overland Road to I-25
An ecological transition zone, an urban reach
To build a model we define relatively
homogeneous river reaches by considering
flow diversions, channel form and floodplain
connectivity, armoring and encroachment…
12
What What is is a a healthy healthy and and resilient resilient
Poudre Poudre River? River?
• Clean water, abundant wildlife, and flourishing
riparian forests
• Functioning ecological processes – e.g., dynamic
interactions between flow patterns and physical
habitat
• Self-sustaining – the river can maintain habitats
and riparian forest itself
• Supports biodiversity through habitat diversity
13
5 5 Biological Biological Indicators Indicators
Categorical conditions (--, -, 0, +)
– native fish
– brown trout
– riparian vegetation
– aquatic insects
– algae
14
15
16
17
18
Flow scenario
High flow functions Channel structure
Climate Local Management
Low flow functions
Algae
Aquatic insects
Native fish Trout
Riparian vegetation
19
ERM Linkages
Fine
Sediment
Flushing
Flow
Nutrient
loads
Air
Temp
Baseflo
w
Low Bench
Inundation
Flow Coarse
Substrate
Mobilization
Flow
Channel
Migration
Flow
Overbank
Flow
Longest
Drought
Sequence
Point
Discharge
Non‐Point
Discharge
Floodplain,
streambank,
and channel
management
Plant
Management
Water
Temp
Dissolved
Oxygen Algae
Channel
Substrate
Channel
Structure
Native
Fish
Streamside
Vegetation
Trout
Water
Management
Fish
Stocking
Invertebrates
20
ERM Linkages
Fine
Sediment
Flushing
Flow
Nutrient
loads
Air
Temp
Baseflo
w
Low Bench
Inundation
Flow Coarse
Substrate
Mobilization
Flow
Channel
Migration
Flow
Overbank
Flow
Longest
Drought
Sequence
Point
Discharge
Non‐Point
Discharge
Floodplain,
streambank,
and channel
management
Plant
Management
Water
Temp
Dissolved
Oxygen Algae
Channel
Substrate
Channel
Structure
Native
Fish
Streamside
Vegetation
Trout
Water
Management
Fish
Stocking
Invertebrates
21
22
Model Model input input and and output output
• Primary model inputs are river flow scenarios – a
flow scenario is a dataset that describes patterns
of flow over time at various points on the river
• Flow scenarios provide a plausible range of
possible future hydrologic conditions on the river
for investigating risks and vulnerabilities
• Example scenario – status quo operations
continued for the next several decades
23
State Definition
--
Low diversity (4 or fewer taxa in warmwater streams) and
abundance (<100 individuals total) in standard sampling
effort, single life stages for most species
-
Low diversity (6 or fewer taxa in warmwater streams) or
abundance (<100 indivduals total) in a standard sampling
effort, single life stage for many species
0
Moderate diversity (7-12 taxa in warmwater streams) and
abundance (100-1000 individuals total in standard
sampling effort), 2 or more life stages per species
+ High diversity (>12 taxa in warmwater streams) and high
abundance (>1000 individuals total), multiple life stages
Example of ERM Output for Native Fish populations; definitions of the
states are provided in the table above.
24
How How are are flow flow scenarios scenarios assessed assessed in in
the the model? model?
Flow is the ““ccoonndduuccttoorr”” or master variable of the
river ecosystem
5 key characteristics:
Magnitude
Frequency
Duration
Timing
Rate of Change
25
ERM ERM Preliminary Preliminary Results Results
What What might might we we be be concerned concerned about? about?
• Both trout and native fish populations could
decline, and both populations could become more
vulnerable and in danger of collapse.
• The corridor of riparian vegetation and forest
along the river is likely to be narrower, and lacking
regeneration of native species.
• Further reductions in abundance and diversity of
aquatic invertebrates (insects).
• Elevated nutrient levels
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Opportunities Opportunities for for effective effective
management management actions actions
• Preliminary work with the ERM shows that there may be
combinations of feasible management actions that can slow
or prevent declines in some or all of the biological indicators.
• These actions could include provision of minimum flows in
winter and summer, flushing flows, modification of armoring
in safe locations, and reestablishing diverse habitats.
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Next Next Steps Steps
• Model testing, verification and validation, refinement,
model runs, and interpretation
• Share the model with the public, potentially thru an open
house format in fall of 2012
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• Does Council have any questions about the
model?
• Does Council have any suggestions or concerns
regarding the model or how it will be used?
• Would Council like staff to return and present
results of the final model (which we anticipate will
be complete by summer) or would Council prefer
to receive a copy of the report?
General General Direction Direction Sought/Sought/Specific Specific
Questions Questions