Cumulative impact assessments for Shoreline Management

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Cumulative impact assessments for Shoreline
Management
Pacific Northwest RGIS Center for Spatial
Information Central Washington University
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Objectives

• Review the regulatory requirements for cumulative
  impact analysis relevant to shoreline management
  under WA rules and laws
• Step through an approach for analyzing cumulative
  effects
• Summarize some case studies

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WA State requires cumulative impact analyses for

• Local government Shoreline Master Programs (SMPs)
  
• State Environmental Policy Act (SEPA)
• Shoreline Conditional Use Permits (CUPs)

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Shoreline Master Program

• SMP Guidelines WAC 173-26-186(8)
• SMP should evaluate and consider cumulative
  impacts of reasonably foreseeable future
  development on shoreline ecological functions
• Evaluation of such cumulative impacts should
  consider
• current circumstances affecting the shorelines
  and relevant natural processes
• reasonably foreseeable future development and use
  of the shoreline and
• beneficial effects of any established regulatory
  programs under other local, state, and federal
  laws.

..consider the effect on the ecological
functions of the shoreline that are caused by
unregulated activities, development exempt from
permitting, effects such as the incremental
impact of residential bulkheads, residential
piers, or runoff from newly developed properties.
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Develop a plan to monitor cumulative impacts
SMP Guidelines WAC 173-26-191 (2)(a)iii (D)
Documentation of project review actions and
changing conditions in shoreline areas. Master
programs or other local permit review ordinances
addressing shoreline project review shall include
a mechanism for documenting all project review
actions in shoreline areas. Local governments
shall also identify a process for periodically
evaluating the cumulative effects of authorized
development on shoreline conditions.
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Shoreline Conditional Use Permit
Local governments can require a CUP even if a
proposed use is otherwise exempt from permit
requirements (e.g. bulkheads for single family
residences). Local planners must consider the
cumulative effects of approving conditional uses.
The State Dept. of Ecology has final approval
authority on all CUPs.
must consider the cumulative impact over time of
granting additional permits for like actions in
the area. If comparable development proposals are
likely and were permitted by CUP in the area
where similar circumstances exist, the total of
the developments must not produce substantial
adverse effects to the shoreline environment WA
State Supreme Court Hayes v. Yount, 87 Wn.2d
280, 287-88, 552 P.2d 1038 (1976).
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Cumulative impacts SEPA

• SEPA review required for new Shoreline Master
  Program AND individual project review
• Must assess cumulative effects for determination
  of non-significance or apply mitigation sequence
  where appropriate

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Three Case Studies

• McLane Creek Basin, Thurston County Cumulative
  effects of zoning on impervious surface. Provide
  a comprehensivegt step by step presentation
• Moses Lake, Grant County Cumulative effects of
  pier and dock development on shorelinegt brief
  review
• Jackson Beach, San Juan County Cumulative
  effects of shoreline activities on sediment
  transport processesgt brief review

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McLane Creek Basin StudySan Juan County, WA

• Janet Rhodes
• Cinde Donoghue
• Central Washington University, Center for Spatial
  Information (CSI)

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Step through approach with example McLane Creek,
Thurston County WA
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Describe geographic boundaries
McLane Creek Basin, Eld Inlet drainage of
Deschutes watershed in Thurston County, WA
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Describe scope of analysis

• Zoned long term forestry, resource reserve and
  residential
• Nature trail state owned land (DNR)as well as
  residential (privately owned parcels)
• Assess impacts of
• Expanded timber harvest
• expanded preserve area- recreational use
• residential down-zoning
• Implement low impact development

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Zoning and land use - McLane Creek Study Area
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Characterize the regional landscape

• Apply findings from analysis of ecosystem wide
  processes required for SMP update.
• Steep slopes, hydric and highly erodable soils,
  poor drainage.
• Consider historical and planned uses and the
  existing constraints of zoning and regulations.
• Long Term Forestry- past and future timber
  harvest
• Portion of Rural Reserve in nature preserve-
  primarily passive recreational use
• Residential development RR 1/1 and RR 1/2
• Long term agriculture- previously active crop and
  livestock currently mostly tree farm and hobby
  farms

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Describe what actions/projects will be assessed
in the analysis

• Potential actions for McLane Creek area
• Expanded timber harvest
• expanded preserve area- recreational use
• residential down-zoning lower residential
  density, potentially increase non-regulated
  agriculture
• low impact development (cluster, engineered BMPs,
  green architecture, pre-devlopment permit
  stormwater facilities)

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Identify Timeframe for the Analysis

• Temporal boundaries for the affected resources
  will include a comparison of baseline conditions
  to historic trends, and estimate of impacts over
  next twenty-five years

1943
1973
1991
1996
2001
2006
2031
1986
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Affected Resources

• Listed fish and wildlife species
• Salmonid breeding, rearing, migrating.
• Beaver
• Pileated woodpecker breeding
• Rough skinned newt breeding, rearing, migrating
• Important habitat
• Old growth,
• Forest edge,
• beaver pond,
• wetland,
• riparian

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Methods

• Create matrix or systems diagram linking each
  activity to affected resources.
• 2. Geospatial analysis of baseline conditions
  (using remotely sensed imagery and field data).
  Use historic data (aerial photos and maps) to
  estimate build-out based on development trends
  and population growth for 25 years.
• 3. Scenario modeling of different zoning,
  development, and regulatory regimes.

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Classes of impacts
Class
Action
Impact
Direct- action and impact occur at same time
place
logging
Indirect- secondary effects resulting after or at
some distance from action
Transport of logs from harvest site
Cumulative- single or multiple source effects
that may be additive, interactive or synergistic
Reduction in tree canopy, tree root mass
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Impacts Matrix
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McLane Creek Basin-Trend in impervious surface
presence
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McLane Creek Basin- Trends in total forest cover
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McLane Creek Basin- Trends in forest
fragmentation
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Shoreline structures
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McLane Creek Basin-Future trend in impervious
surface presence
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McLane Creek Basin- Future trends in total
forest cover
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Consider indicators relative to specifics of the
site

• Is the resource especially vulnerable to these
  incremental effects?
• Is the proposed action one of several similar
  actions in the same geographic area?
• Have these effects have been identified on this
  resource from historic activities?
• What regulatory schemes can be applied to avoid
  or mitigate impacts

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Effects Specific to McLane Creek

• Listed species especially vulnerable to
  degraded water quality and disturbed riparian
  area.
• Preserve area provides opportunity for passive
  recreation in functioning natural area short
  distance from urban center. Significant
  shoreline structure and compaction of riparian
  trails
• Rapidly developing adjacent lands nearby areas
  are zoned for relatively small parcel residential
  development (opportunities for clustering or
  expensive engineered BMPs are limited)

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Scenarios modeling

• Runoff
• Runoff Curve Number (CN)
• Time of Concentration (Tc)
• Retention
• Detention

Steps
Determine Percentage of Each potential Land
Use/Cover
Calculate runoff based on the specific BMPs
applied (e.g. pervious surfaces, grading, swales
etc.)
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Scenario modeling

• Forest Fragmentation

Develop scenarios with zoning and regulations
based on biophysical characteristics- e.g.
delineate resource reserve zoning along flow
paths and wildlife corridors. Input land cover
type that reflects vegetation conservation
regulations for required by each zone (percentage
native vegetation removal, replanting of riparian
zones)
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McLane Creek decision points
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McLane Creek focus scenarios

• Evaluate the impervious surface within the basin
  if the area is
• Down-zoned to lower densities (1/5 to 1/10 or
  1/20)
• Rezoned to Low Impact Development (LID 2/5 and
  LID 4/5)
• Cluster Development (parcels of minimum 10 acres
  can have maximum 10 impervious)

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McLane Creek- prioritize regions
Prioritize based on geospatial habitat
characteristics McLane1 This region contains
highest density of shoreline (wetlands and
streams) and is connected to parcels zoned
Long-Term Forestry (providing habitat
connectivity from the stream/wetlands to the
upland forests). This region is highest priority
for rezoning. McLane2 This region contains
second highest density of shoreline and had a
small number of parcels/landowners. It would
also provide connectivity to the LTF area if
McLane1 is also intact. McLane3 This region
contains third highest density of shoreline and
had a small number of parcels/landowners. It is
also connected to the LTF area. McLane4 This
is the smallest area and is wedged between two
developed residential areas. There is a small
amount of stream and wetland shoreline. McLane5
This includes all the remaining area in McLane
Basin that is zoned at higher density than 1/5
and and essentially at full build out.
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McLane Creek scenario results
Scenario 1 Zone all regions lowest (traditional)
density
Scenario 2 Zone regions mixed (traditional).
Lowest density for priority protection areas 12.
Scenario 2 Zone priority protection regions to
allow only cluster and other regions highest
(traditional) density.
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McLane Creek scenario results cont.
Scenario 4 Zone highest priority protection
regions low densities. Zone other areas Low
Impact Development and highest (traditional)
density
Scenario 5 Zone highest priority region lowest
(traditional) density. Low impact development
and cluster development required inother regions.
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McLane Creek results summary

• The Cumulative Impact Analysis allowed for
  sub-basin specific zoning comparison
• Zoning all regions traditional low density is
  most effective at limiting total and percentage
  impervious acreage however it also has greatest
  effect on reducing number of dwelling units.
• Zoning priority protection regions traditional
  low density and the less sensitive areas higher
  density more than doubles the percentage of
  impervious surfaces, while providing less than a
  20 gain in dwelling units.
• Targeting priority protection regions for low
  density and requiring clustering and development
  in less sensitive areas increases total
  impervious surface by 3, however the bulk of
  this increase is located outside of sensitive
  areas and there is greater than 100 gain in
  residences.

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Moses Lake StudyGrant County, WA

• David Cordner, Janet Rhodes, Cinde Donoghue
• Central Washington University, Center for Spatial
  Information (CSI)

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Moses Lake- study area and context
The city of Moses Lake has experienced moderate
growth over the years. In 2001 the city's
population was near16,000. As a result of the
city's growth, it has become known as a
commercial, recreational, and service center for
the entire area.
Moses Lake is a shallow warm water lake that was
created as a result of ice age glaciers and
ancient floods that moved across eastern
Washington The lake is over 20 miles in total
length, approximately 11 square miles in
totalarea, and has a mean depth of 18.5 feet.
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Moses Lake- over water structures
Rapid development has occurred over the last 15
years in several unincorporated areas beyond the
city boundaries. The lake is primarily used for
recreational purposes such as boating, fishing,
jet skiing, and swimming. There is increasing
pressure for the development of single family
over water structures such as piers, docks and
boat ramps.
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Moses Lake- reach selection

• Four reaches of similar shoreline length
  (indicated in purple and labeled 4, 7, and 29N
  and 29S in the map to the left),
• were selected representing a variety of buildable
  potential

29N
7
4
29S
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• Moses Lake overwater structure development
• Calculate the number, length, and area of docks
  construction for a given reach for different
  scenarios
• Including only existing residential lots
• With all possible new docks being individual
  docks
• With all possible new docks being shared docks
• With all possible new docks being substituted by
  sharing existing docks
• Including all undeveloped parcels, assuming they
  are rezoned and subdivided into residential lots
  with the same amount of shoreline as existing
  lots
• With all possible new docks being individual
  docks
• With all possible new docks being individual
  docks, except for newly subdivided parcels,
  prohibit individual docks and allow one
  community-use dock per newly subdivided parcel
• With all possible new docks being shared docks
• With all possible new docks being substituted by
  sharing existing docks
• With all possible new docks being shared docks,
  except for newly subdivided parcels, prohibit
  individual docks and allow one community-use dock
  per newly subdivided parcel
• With no new docks allowed on newly subdivided
  (currently undeveloped) parcels, and a public
• dock built on one of the open-space
  (currently undeveloped) parcels instead
• With all possible new docks being individual
  docks

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Pier and Dock Moses Lake reach 4
All new docks individual
All new docks shared
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Pier and Dock Moses Lake reach 7
All new docks individual
All new docks shared
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Pier and Dock Moses Lake reach 29-N
All new docks individual
All new docks shared
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Pier and Dock Moses Lake reach 29S
All new docks individual
All new docks shared
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Pier and Dock Moses Lake Result Summary
Regulations regarding new docks have greatest
influence on those reaches that are most
undeveloped. Requiring all new docks to be
shared has a modest effect on the relative
difference of total number of future docks.
Requiring existing docks be shared, new docks
be shared and implementing a cap on size and
length can influence the largest nearshore area
of Moses Lake shoreline.
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Jackson Beach StudySan Juan County, WA

• Anthony Gabriel
• Central Washington University, Center for Spatial
  Information (CSI)
• Leo Bodensteiner
• Western Washington University

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Jackson Beach-the setting

• The substrate size composition and mixture of
  sizes are preferred as spawning habitat by surf
  smelt and sand lance.
• The tombolo forms a back bay, Argyle Lagoon,
  which is maintained by the University of
  Washington as marine preserve. Shoreline
  wetlands, such as Argyle Lagoon, are rare in
  Puget Sound and are recognized because of the
  unique habitat conditions they provide
• Are current shoreline activities disrupting the
  processes required to maintain the beachform.

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Jackson Beach- geomorphologic change

• Visual comparison indicates that the size and
  shape of the tombolo in 1960 was not very
  different from a 1897 Government Land Office
  Mapmap
• In 1959 a pier and barge loading facility was
  constructed and began operation

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Jackson Beach- geomorphologic change

• Subsequent to 1960, the tombolo appears to have
  changed relatively rapidly. In particular the
  width and elevation of the beach appear to have
  increased.
• a given location on the beach becomes
  increasingly shallower, indicating that accretion
  is occurring

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Jackson Beach-Findings

• Accretion of the tombolo is attributed to
  transport of the barge operation staging area
  material from the proximal to the distal end.
• Changes to the beach in this area that reduce the
  availability of source material or interrupt
  transport of sediment will slow or stop accretion
  of the tombolo.

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Summary- Analysis of Cumulative Impacts

• Spatially explicit scope place-based cumulative
  impact analysis for each drainage, drift cell or
  shoreline reach.
• Identify time horizons
• future -regulatory requirements
• historical - available data
• Apply current knowledge of area issues
• Findings from analysis of ecosystem-wide
  processes as required for SMP update

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Summary cont.

• Create a matrix or systems diagram to
• identify potential direct, indirect and
  cumulative effects
• Identify indicators that can be feasibly applied
  to evaluate both historic trends as well as
  predict future impacts (limited often by
  mis-match between scale of question availability
  of appropriate data
• Cite sources of indicators or scientific
  literature referencing potential effects that
  cannot be readily measured
• Evaluate effects resulting from different
  zoning/regulatory scenarios relevant to
  basin/reach of interest.