U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2011-3067

July 2011

RESEARCH AT THE USGS WESTERN GEOGRAPHIC SCIENCE CENTER

Land-Use Planning for Nearshore Ecosystem Services—

The Puget Sound Ecosystem Portfolio Model

The Puget Sound region of northwestern 

Washington, home to more than 4 million 

people, comprises a major U.S. estuary with 

many rivers and streams draining an area of 

more than 13,000 square miles. The complicated bays and waterways of the sound have 

2,500 miles of shoreline—bluffs, beaches, 

mudflats, kelp and eelgrass (Zostera marina) 

beds, salt marshes, gravel spits, and estuaries. This highly productive zone supports 

valuable fishing, shellfishing, and recreation 

industries, which contribute billions of dollars to the State’s economy. The food, water, 

cultural, and recreational benefits people 

obtain from nearshore environments are 

considered “nearshore ecosystem services.”

The Puget Sound region continues to 

experience rapid development and growth 

in population, which is expected to reach 

5.4 million residents by 2025. This future 

growth can affect nearshore ecosystem 

services by increasing water pollution and 

nutrient loading and by modifying coastal 

habitats. The land-use decisions made to 

accommodate this growth will influence 

whether Puget Sound environments are 

further degraded, maintained, or successfully 

restored. Resource managers need tools to 

identify where and why potential impacts 

to ecosystem services may occur to plan for 

ensuring their long-term sustainability. 

The many benefits to people (ecosystem services) of the Puget Sound, Washington, nearshore are illustrated 

by (clockwise from upper left) recreational boating at Port Hadlock marina (photo © Hugh Shipman); fishing 

(photo © JPaul Grow); mussel harvesting (photo © Jon Rowley); and waterfront living in Anacortes (photo 

© Hugh Shipman). The Puget Sound Ecosystem Portfolio Model will provide planners data needed to 

accommodate expected growth and development while preserving and protecting these ecosystem services.

The Puget Sound, Washington, region (watershed 

outlined here) includes intricate waterways that 

stretch along 2,500 miles of shoreline and adjacent 

nearshore waters.

Although it is not known where and 

how much development will occur in the 

future, the influences of population growth, 

regulations, and public preference can be 

monitored. Instead of trying to predict 

development patterns, planners can develop 

scenarios, which may include maps that 

show, for example, where people might 

live and work in 2060. Scientists can then 

determine how the nearshore ecosystems 

may change under each scenario.

The Puget Sound Ecosystem 

Portfolio Model

The U.S. Geological Survey (USGS) 

Western Geographic Science Center 

(WGSC) has been working with the U.S. 

Environmental Protection Agency, shoreline 

planners, public health officials, and others 

to develop the Puget Sound Ecosystem 

Portfolio Model (PSEPM). Based on earlier 

efforts (http://pubs.usgs.gov/sir/2009/5181/), 

the PSEPM is a decision support tool that 

uses scenarios to evaluate where, when, and 

to what extent future population growth, 

urban development, and shoreline development may alter the nearshore environment 

The 2,500 miles of shoreline and 

nearshore areas of Puget Sound, 

Washington, provide multiple benefits 

to people—“ecosystem services”—

including important fishing, shellfishing, 

and recreation industries. To help resource 

managers plan for expected growth in 

coming decades, the U.S. Geological 

Survey Western Geographic Science 

Center has developed the Puget Sound 

Ecosystem Portfolio Model (PSEPM). 

Scenarios of urban growth and shoreline 

modifications serve as model inputs to 

develop alternative futures of important 

nearshore features such as water quality 

and beach habitats. Model results will 

support regional long-term planning 

decisions for the Puget Sound region.

WASHINGTON

Tacoma

Seattle

Tacoma

Seattle

Land Cover

Urban

Forest

0 20 40 Miles

0 30 60 Kilometers
50 years from now. The tool focuses on 

impacts to barrier beaches and bluff-backed 

beaches, which represent 50% of Puget 

Sound shorelines by length.

The PSEPM presents three possible 

futures of the nearshore by analyzing three 

growth scenarios developed out to 2060:

• Status Quo—continuation of current 

trends.

• Managed Growth—adoption of an aggressive set of land-use management policies.

• Unconstrained Growth—relaxation of 

land-use restrictions. 

These scenarios were developed by 

scientists at Oregon State University and 

provide information on projected population, land cover, and, in coastal areas, 

shoreline modifications (see http://

envision.bioe.orst.edu/StudyAreas/

PugetSound/index.html). PSEPM model 

outputs include maps that identify 

shoreline sections where nearshore 

resources may be more strongly affected by 

changes on the land.

Model Subcomponents and Results

The PSEPM comprises three submodels—

the Shellfish Pollution Model, the Recreation 

Visits Model, and the Beach Armoring 

Index—that identify connections between 

changes on the land and the capacity of the 

nearshore to support ecosystem services. 

Results from the PSEPM identify where and 

when future changes to nearshore ecosystems 

and ecosystem services will likely occur within 

the three urban growth scenarios. The model 

results will improve understanding of potential 

changes in nearshore ecosystem services by:

• Highlighting resource-rich areas that may 

potentially be affected by multiple stressors;

• Helping to prioritize sites for further 

study and higher level conservation and 

restoration planning;

• Providing planners with the ability to 

focus on targeted areas in order to meet 

regional land-use planning goals; and

• Providing the foundation for evaluating changes in Puget Sound ecosystem 

services within integrated scenarios of 

climate change and land-use change.

The work of Western Geographic 

Science Center (WGSC) scientists in 

developing the Puget Sound Ecosystem 

Portfolio Model is only part of WGSC’s 

efforts to better understand the causes 

and consequences of land-cover change. 

WGSC is continuing productive collaborations with public land managers, 

tribal leaders, and local communities to 

help ensure that they have the crucial 

information they need to make informed 

decisions about ongoing and future landuse choices.

Kristin Byrd

Edited by Peter H. Stauffer

Graphics and layout by Jeanne S. DiLeo 

COOPERATING ORGANIZATIONS

U.S. Environmental Protection Agency

Oregon State University

Washington State Department of Ecology

Washington State Department of Health

Washington State Parks and Recreation Commission

Natural Capital Project, Stanford University

For more information contact:

Kristin Byrd

U.S. Geological Survey

345 Middlefield Road, MS 532

Menlo Park, CA 94025

Tel. (650) 329-4279

kbyrd@usgs.gov

http://geography.wr.usgs.gov/

http://geography.wr.usgs.gov/pugetSound/index.htm

This Fact Sheet and any updates to it are available 

online at http://pubs.usgs.gov/fs/2011/3067/

Users of the PSEPM Web site (http://geography.wr.usgs.gov/pugetSound/index.html) can view model results 

and compare scenarios using a Web-based mapping application. A three-map viewer allows the user to 

view, compare, and contrast results at the data-point scale or at the regional scale across three scenarios 

simultaneously. Model results can also be downloaded on a data download page. 

Scenarios of future growth (green 

box) drive submodels of nearshore 

change (purple boxes). Submodel 

outputs are used to assess future 

changes to ecosystem services (blue 

boxes). The submodel results may 

provide information about more than 

one ecosystem service. For example, 

Beach Armoring Index results affect 

the spawning potential of forage fish 

(small fish that larger predators eat) 

and recreational beach quality, which 

is also affected by Recreational Visits 

Model results.

Puget Sound Ecosystem Portfolio Model Subcomponents

Scenarios of urban growth/population distribution/shoreline modification

Beach Armoring Index

Uses scenarios of shoreline 

modification to rank beaches based 

on the potential for physical and 

ecological changes due to cumulative 

onsite and updrift armoring.

Recreation Visits Model 

Uses scenarios of population 

distributions in Puget Sound to 

model changes in State Park beach 

visitation and stresses on 

recreational resources. 

Shellfish Pollution Model 

Uses scenarios of land-cover change to estimate 

fecal coliform bacteria concentrations in 

commercial shellfish growing areas, given 

expected development patterns in watersheds 

draining to the nearshore.

Recreational 

shellfish harvesting

Recreational beach 

quality

Commercial/Tribal 

shellfish habitat suitability

Forage-fish spawning 

potential