Sustainable Stormwater? Hydrologic and Ecologic Implications of Limited Surface Infiltration in the Tryon Creek Watershed

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Sustainable Stormwater? Hydrologic and ecologic implications of limited surface infiltration in the Tryon Creek watershed

Megan Taylor

Environmental Studies Lewis & Clark College, Spring 2007

Abstract: The infiltration of stormwater is recognized in Portland City stormwater policy as an essential process for the functioning of healthy watershed ecosystems. Despite this commitment, current policy prevents the installation of surface infiltration facilities in the Tryon Creek watershed due to its steep slopes and low-permeability substrate. My study closely examines this discrepancy, and the high-risk financial liabilities that inform it. Limited infiltration has, and will continue to have, serious consequences for flora and fauna that utilize stream and riparian habitat, including threatened salmonid and lamprey eel populations. This study assesses the effectiveness of current management practices and alternative strategies for increasing infiltration. The degree to which these strategies can establish ecologically supportive flow regimes is explored in the context of current restoration efforts in the Tryon Creek watershed.

Taylor 2

The City of Portland, Oregon is widely viewed as a forerunner in the successful implementation of green technology and sustainable development in urban design. One example of such planning initiatives is the Urban Growth Boundary (UGB) that encircles the city and promotes high-density infill development to prevent urban sprawl (Urban growth boundary 2006). Though widely considered an environmentally friendly move, this densification is in tension with the work of multiple government agencies and community-based organizations to maintain and restore the sensitive rivers and streams that fall within this boundary.

In order to combat the negative effects of increased urbanization on watersheds, in 2005 the City of Portland launched its Actions for Watershed Health plan, which outlines techniques for restoring and maintaining watershed “health.” As defined by the city, a “healthy urban watershed has hydrologic, habitat, and water quality conditions suitable to protect human health and maintain viable ecological functions and processes, including self sustaining populations of native fish and wildlife species (9)” (Actions for watershed health 2005).1 Such a standard becomes increasingly difficult to attain as development blankets higher proportions of these watersheds with impervious surfaces in the form of homes, driveways, parking lots, and streets. Rainfall that would have otherwise made its way through the drainage basin underground (i.e. infiltrating to subsurface throughflow or groundwater base flow) is routed into overland flow, entering streams and rivers directly (Fig. 1).

1 Any reference to watershed or ecosystem “health” in the following pages is based on this definition. Taylor 3

Figure 1. Basic hydrologic processes and pathways within a basin2

These hydrologic changes create two consequences for the hydraulic, geomorphologic, and subsequently, the ecologic functioning of the receiving channel: 1) the volume of water and the rapidity with which it accumulates increases, leading to channel scouring and bank erosion, and 2) lack of groundwater recharge which may limit summer-time flow.

Portland’s current stormwater policy attempts to mitigate the effects of high- density urbanization on watershed health by decreasing the pollutant load of the stormwater, limiting its erosive flow peaks, and increasing rainfall retention (i.e. infiltration) on-site (Stormwater management manual 2004). Such policy, though widely applauded, suffers from challenges when implemented across an entire city. These

2 Accessed at http://snobear.colorado.edu/IntroHydro/geog_hydro.html (December 2006)

Taylor 4 challenges are especially evident in areas subject to significant physical constraints, such as the Tryon Creek watershed in Southwest Portland.

Portland City policy mandates the design of cutting-edge stormwater management systems for all new development that takes place within the 80% of the Tryon Creek watershed that falls within the city limits (Stormwater management manual 2004). Such systems either decrease total impervious area through the use of green roofs and permeable pavement, or attempt to slow the accumulation of runoff in-channel and promote infiltration via bioswales, detention ponds, constructed wetlands, and flow- through planter boxes (Stormwater management manual 2004). These later surface infiltration facilities are difficult to implement within the Tryon basin due to its steep slopes and clay-rich (i.e., low permeability) soils (Fanno and Tryon Creeks watershed management plan 2005; Castaneda 2006). These geologic constraints inspire fear of financial liability, which has spawned stormwater management policy that prevents infiltration of runoff from taking place within the Tryon Creek watershed (Stormwater management manual 2004; Fancher 2006).

Though highly impacted by stormwater runoff, the Tryon Creek watershed, and especially its mainstem, is believed to be “one of the best remaining stream habitats in the city (52),” and is considered to have great potential for successful restoration (Actions for watershed health 2005). This potential has inspired the non-profit organizations operating within the watershed and the city departments charged with its care to spend millions of dollars on the restoration of Tryon Creek and its tributaries (Tryon Creek watershed 2006; Peterson 2006). This restoration is largely directed toward the rehabilitation of salmonid and lamprey eel populations that once thrived in the Tryon Creek watershed. These responses are often Taylor 5 limited in their application by the narratives that inform our understanding of restoring urban watersheds. The assumption that an urban watershed can be restored to pre- development levels of hydrologic and ecological functioning is woven into the goals for

Tryon Creek’s restoration. This assumption often leads those that care for the Tryon

Creek watershed to 1) believe if we build in-channel habitat, the salmon will return, or 2) adopt a fatalistic view of the watershed’s future inspired by the overwhelming nature of this enormous task. Both of these views illustrate a naïve understanding of the complex, yet resilient nature of urban watershed ecosystems; a misunderstanding that must be overcome before real progress can be made in the watershed.

Increasing surface infiltration from levels currently dictated by stormwater policy is an essential, but often overlooked, step in the process of restoring the Tryon Creek watershed. It is my hope that this study will not only situate the biophysical issue of limited surface infiltration into a political, economic, and societal context, but it will also work to develop a nuanced understanding of what possibilities lie before us. The information synthesized in the following pages was largely gathered through an extensive set of interviews with individuals in the governmental, private, and non-profit sectors, as well as local community members. These interviews, in addition to an in-depth review of stormwater management policy, helped me develop a detailed understanding of the constraints facing increasing surface infiltration in the Tryon Creek watershed. Later in my research process, these many knowledgeable people graciously provided feedback and clarification as I began to explore alternatives for increasing infiltration, as well as the implications of current stormwater policy on the ecologic health of the watershed. Taylor 6

This study begins with a description of the current hydrological and ecological state of the Tryon Creek watershed in the context of urbanization (Section I). I then attempt to illustrate the ways in which current stormwater management practices best support and most conflict with the Policy’s stated goal of maintaining surface infiltration.

Exploring the high-risk liabilities that inform Portland’s stormwater policy will contextualize my critique and illustrate why surface infiltration is limited in this watershed (Section II). I then investigate possibilities for changes in the current management practices to increase surface infiltration in light of this limitation and uncertainty (Section III). Lastly, I consider the restoration efforts currently underway in the Tryon Creek watershed in light of the hydrological, political, and societal limitations

(Section IV).

I. The Tryon Creek Watershed

The Tryon Creek watershed encompasses approximately six and a half square miles (4,142 acres), eighty-percent of which falls in Southwest Portland, Oregon.3 This small watershed is bordered by the Fanno Creek watershed to the North and West,

Stephens Creek watershed to the North, Lake Oswego to the South, and finally the

Willamette River to the East (Fanno and Tryon Creeks management plan 2005). Tryon

Creek is a tributary to the Willamette River and is the “one remaining free-flowing tributary that descends from the Portland West Hills (2-17)” (Fanno and Tryon Creeks

3 Though nearly twenty percent of the Tryon Creek watershed lies outside of the Portland city limits, in the city of Lake Oswego, and Multnomah and Clackamas counties, for the purposes of this paper, I focus solely on this portion of the watershed that falls under the jurisdiction of Portland’s Stormwater Management Policy. From now on, any reference to the Tryon Creek Watershed refers to that portion which falls within the city limit. Taylor 7 management plan 2005) (Figure 2). Two major tributaries, Falling Creek and Arnold

Creek, feed the Tryon Creek mainstem. In total, the system has nearly 30 miles of stream, only three of which are piped or pass through culverts.

Like much of Portland, the Tryon Creek Watershed has experienced a tremendous rate of growth and new development in recent years. Impervious surfaces, which encompassed 24% of the entire watershed in 2005, are expected to increase to 28% by

2040 (Upper Tryon corridor assessment 1997). As of the 2000 US census, the Tryon

Creek watershed is home to nearly 18,000 residents (Fanno and Tryon Creeks management plan). The watershed is currently dominated by relatively low-density land use, with 55% of the watershed zoned as single family residential. Parks and open space, which include the 630-acre Tryon Creek State Natural Area (TCSNA), encompass another 14% of the watershed. Areas zoned for commercial and multi-family residential use are concentrated near Interstate-5 and Highway 99 (Barbur Blvd.) that pass through the watershed’s headwaters (Fanno and Tryon Creeks management plan 2005). Taylor 8

Figure 2. Map of Tryon Creek Watershed4

4 Accessed at http://www.portlandonline.com/bes/index.cfm?c=43107&a=128946 Taylor 9

The Hydrology of the Tryon Creek watershed

In a recent report, the Portland’s Bureau of Environmental Services (BES) employed hydrological modeling software to develop an understanding of how rainfall is allocated in the basin. In a typical year, 23% of rainfall results in direct runoff, 26% drains to streams and rivers as subsurface flow, 47% is lost as evaporation, and 7% infiltrates the groundwater reserves that feed base flow (Fanno and Tryon Creeks management plan 2005).

Of the approximately 42 inches of precipitation that the basin experiences annually, three quarters of it falls in the winter months (November-May), while the remaining quarter falls in the summer (June-October).5 This summer rainfall is concentrated early and late in the season, while the months of July and August each experience less than one inch of rainfall on average (Fanno and Tryon Creeks management plan 2005). Rain events that occur in the summer are, on average, half as long as winter storms, and occur half as frequently. This seasonal rainfall behavior

“strongly influence[s] streamflow regimes in the watershed, particularly the low flows that are characteristic during late summer” which are dominated by “groundwater recharge to the streams (4-1)” (Fanno and Tryon Creeks management plan 2005).

While direct runoff pathways accounts for 23% of total annual rainfall, the importance of this pathway changes dramatically over the course of the year. The monthly runoff coefficient is the proportion of runoff volume to rainfall volume. The line in Figure 3 illustrates how values of this coefficient vary over the course of a year. Early

(November 2006) 5 As there is no rain gauge in the Tryon Creek watershed, a gauge at the Portland Community College Sylvania campus in the Fanno Creek Watershed is used as a surrogate. Taylor 10 in the wet season only ten to twenty percent of rainfall runs off into the Tryon creek system, resulting in the infiltration of approximately 80-90% into soil storage and groundwater reserves. As the groundwater reserves recharge, and subsurface pore space fills, this proportion steadily increases to its peak in March at nearly 90% runoff (Fanno and Tryon Creeks management plan 2005).

Figure 3. Tryon Creek Watershed Drainage for USGS Stream Gauge below Nettle Creek (Fanno and Tryon creeks management plan 2005)

This high runoff behavior is dictated by the soil composition of the basin.

According to the National Resources Conservation Service (NRCS), the Tryon Creek watershed is dominated by the Cascade series soils group, with 98% of the soils classified as type C hydrologic soils, and with isolated pockets of type D soils (Upper Tryon Creek Taylor 11 corridor assessment 1997). These soils are considered sandy clay loam, and clay loam respectively, both of which are very slow to infiltrate and both of which generate high volumes of runoff (Fanno and Tryon Creeks management plan 2005).

The high runoff potential of the native soils is amplified by the steepness of the

Tryon Creek watershed. Sixty to 75% percent of the upland slopes (i.e. not including channel banks) exceed a 30% grade; some even exceed 50%. According to the SW Hills

Resource Protection Plan, slopes in excess of 30% have “severe landslide potential (ES

3)” (Upper Tryon Creek corridor assessment 1997). These steep slopes increase both the volume, by limiting the formation of pools for storage and infiltration, and the velocity of stormwater runoff that enters Tryon’s streams, increasing the peak flow (i.e. maximum flow volume) within the creek during storm events. While average base flow during the winter months is approximately ten cubic feet per second (cfs), a storm event may increase average to 60-120cfs. Peak instantaneous flows have reached 340cfs and 447cfs, as measured in the 2002 and 2003 water years respectively, which represent increases of

30 to 40 times average daily flow volumes (Fanno and Tryon Creeks management plan

2005).

Ecological Implications of Watershed Hydrology

The rapid, high volume storm response, or “flashy” hydrology, reduces habitat quality for the diverse set of fish species that once thrived in the system. These include chinook, coho, and winter steelhead, as well as Pacific and Western brook lamprey

(Fanno and Tryon Creeks management plan 2005, Gaskill 2006). While an increasingly smaller group of juvenile chinook still use the lower portion of Tryon Creek for rearing Taylor 12 and resting, the coho and steelhead that historically spawned and reared throughout the basin have been reduced to 1.5% to 1% of their historic populations respectively (Fanno and Tryon Creeks management plan 2005). The system still supports a small population of resident cutthroat trout that exist year-round in the basin, and are considered to be

“remnant populations of both searun and resident populations (11-9)” (Fanno and Tryon

Creeks management plan 2005). Both the winter-run steelhead and cutthroat trout have been listed as threatened under the Endangered Species Act. While native lamprey species have been known to use the basin historically, the last adult sighting occurred in

1996 (Peterson 2006).

The concentrated high volume flows experienced by this watershed scour the channel of gravel required for salmonid spawning and the development of thriving populations of macroinvertebrates. Without gravel to protect the bottom of the channel, the high velocity flows erode downward, thereby deepening the channel in a process called entrenchment. Entrenchment increases the gradient of the stream, which increases flow velocity and limits the formation of habitat heterogeneity (in the form of riffles, pools, and large woody debris dams) necessary for the successful spawning and rearing of salmonids (Reiser & Bjornn 1976). The same force that acts on the bottom of the channel during these increased flows also works to erode channel banks,6 which steepen through a process of undercutting and bank failure (i.e. landslides). These failures deliver large quantities of silt and clay (the main bank material of the Tryon basin) into the stream system. While the larger grained silt settles out of the water, the microscopic clay

6 This force is known as tractive force and is a function of water density (a constant), water depth, and channel slope. Water “velocity” is often used as a surrogate to describe tracitve force, and is useful in envisioning the general relationship between increased flows and increased erosive force. Taylor 13 particles remained suspended and can interfere with the respiration of gilled aquatic species (Reiser & Bjornn 1976). The silt that settles out of the stream and onto the channel bottom acts like a cement on the remaining gravely substrate, which would make it extremely difficult for female salmonids to dig their redds (nests), and would likely suffocate eggs and small juveniles (Quinn 2005).

The steepening of the banks makes it difficult for plants to root near enough to the stream to shade and cool the water. In 1996, the Oregon Department of

Environmental Quality listed the Tryon Creek watershed as “water quality limited” because of its abnormally high summer temperatures (Upper Tryon Creek corridor assessment 1997). These high temperatures decrease the amount of dissolved oxygen in the streams, which again interferes with the respiration of aquatic species. This riparian vegetation is further negatively impacted by entrenchment, which lowers the water table within the channel and adjacent floodplain, depriving the riparian plants of the constant water supply necessary for survival (Brady 2007). These challenges come in addition to fish passage barriers in the form of two main culverts located under SW Macadam and

SW Boones Ferry Rd.

Urbanization in the Tryon Creek Watershed

Many of the “problems” (i.e. erosion, slope failure, channel bed incision) associated with the flashy hydrology of this basin are due in significant part to the relative smallness and steepness of this basin, as well as the low permeability of native soils mentioned before. All of these factors lead to a quick in-stream response to storm Taylor 14 events.7 This said it is the urbanization of this basin, and the introduction of impervious surfaces, that has dramatically amplified the effects of this flashiness. These impervious surfaces decrease the ability of rainfall to infiltrate into soils and increase the volume of stormwater that enters stream channels directly or through a conveyance system of pipes, culverts, and/or ditches.8 This increased pressure on the receiving channels has not only lead to the physical degradation of stream habitat, but has prevented a significant proportion of stormwater from infiltrating into soils and groundwater reserves (Fanno and Tryon Creeks management plan 2005).

As of 2005, 24% of the Tryon Creek watershed was covered in impervious surfaces, with most concentrated in the headwaters of the system near the 1-5 corridor

(Fanno and Tryon Creeks management plan 2005). This percentage is expected to increase to 28% by 2040, as multifamily and single-family residential land-use decreases and commercial land-use increases (Upper Tryon Creek corridor assessment 1997).

According to an index developed by The Center for Watershed Protection, the Tryon

Creek watershed is currently classified as “impacted” (impervious surfaces at 11-25%) by elevated streamflows following storm events and stream channel instability. If impervious surfaces increase to 28% by 2040 as predicted, the system will then be

7 Small watersheds are more likely to experience a flashy hydrology, because the distance from any point in the watershed to a channel is less. Therefore, the time it takes rainfall to accumulate into a channel is shortened. 8 The Tryon basin has separate sanitary and storm sewers, the latter of which convey stormwater via a network of pipes directly to the stream channel, or connect with pipes that deliver the stormwater to a water treatment facility for later discharge into the Willamette River (Upper Tryon Creek corridor assessment 1997). Currently, the exact proportion of runoff being delivered directly to Tryon’s streams is not known. According to Greg Savage of Portland BES, much of the Tryon Basin was “developed as a patchwork of infill development before it was annexed to the city,” so mapping of the various drainage facilities and their outfalls (points of entrance into the creek) is “in a state of want” (2007). Taylor 15 classified as “non-supporting” (>25% impervious surfaces) of high trophic-level aquatic organisms due to “severe widening, downcutting, and streambank erosion (4-13)” (Fanno and Tryon Creeks management plan 2005). These observations focus on the physical impacts of high flows, but fail to address potential degradation associated with low summer flows, which will also shape the streams ability to support aquatic organisms.

Though the system has relatively less impervious surfaces than other, larger urban watersheds, these impervious surfaces have an amplified impact on this smaller, steeper, runoff-prone watershed (Actions for watershed health 2005). These impacts are especially worrisome, as the restoration of Tryon Creek is considered to have great potential for the successful rehabilitation of fish populations.

Surface Infiltration in the Tryon Creek watershed

Considered by some to be “the most complete solution to the problem of urban stormwater (191), ” increasing surface infiltration attempts to mimic the hydrologic pathways of less disturbed watersheds (Ferguson 1998). Infiltration is simply defined as the “soaking of water into the ground,” and whose rates are largely dependant on the soil type, degree of vegetation, and antecedent conditions. Infiltration not only decreases the volume of water entering streams directly as runoff, it increases the volume of water entering groundwater reserves, guaranteeing summer flows sufficient to support wildlife.

Although the importance of groundwater as a source of base flow has not been quantified in the Tryon Creek watershed, summer base flows are thought to be lower than they have been in the past due to decreases in groundwater recharge through the construction of Taylor 16 impervious surfaces and “conveyance systems (4-34)” that limit infiltration at the surface

(Fanno and Tryon Creeks management plan 2005).

Despite this lack of quantified knowledge concerning the groundwater in the

Tryon Creek watershed, one can easily reason that a basin naturally characterized by high runoff, low recharge, and low summer flows is vulnerable to the impacts of urbanization that further decreases recharge. Due to this concern, one would expect stormwater management to focus, not only decreasing high volumes of stormwater from entering streams, but increasing recharge as well. While both of these concerns are woven into the stated goals of Portland Stormwater policy, they are largely left unfulfilled in the Tryon

Creek watershed.

II. Stormwater Management in the Tryon Creek Watershed

Stormwater management is defined by the City of Portland as “the overall culmination of technology used to reduce pollutants from, detain and/or retain, and provide a destination for stormwater to best preserve or mimic the natural hydrologic cycle… (1-14)” (Stormwater management manual 2004). The policy outlines specific goals for reducing stormwater runoff from all development or redevelopment projects that take place within Portland city limits. This detailed stormwater policy was created in response to City policy that directed stormwater to be managed “as close as practicable to development sites,” and that these management practices “avoid a net negative impact on nearby stream, wetlands, groundwater, and other water bodies (city code 17.38.025)”

(Stormwater management manual 2004). The Stormwater Management Manual, Taylor 17 published by BES in 1994 and revised in 2004, presents these policies in the form of requirements for development.

Though the stormwater policy is written and enforced by BES, an advisory board made up of representatives from the City Bureaus, the Home Builders Association,

Metro, and the Oregon Department of Environmental Quality (DEQ), as well as watershed advocates, is responsible for making recommendations to improve the policy.

These recommendations largely focus on ways to better align the policy not only with the financial concerns of private property owners and city bureaus, but with other city-wide environmental and social goals as well (Stormwater management manual 2004). The management manual, which is reviewed and updated every three years,9 works to ameliorate four problems: 1) the erosion of stream channels, 2) Combined Sewer

Overflows (CSOs)10, 3) high pollution levels in runoff, and lastly, 4) limited groundwater recharge. Generally, these problems are addressed through the modification of stormwater drainage systems to increase infiltration and maximize evapotranspiration, increase the reuse and/or detention of the water onsite, treat stormwater to remove pollutants, and separate the stormwater and sanitary flows that currently exist in combined sewers (Actions for watershed health 2005). These actions are “intended to protect downstream properties, infrastructure, and natural resources” (Stormwater management manual 2004).

9 BES is currently reviewing the policy and will release a new edition sometime later this year. 10 CSOs are common to the Portland area, and result from high volumes of stormwater entering undersized sewer pipes that convey both stormwater and sewage. In periods of heavy rain (and thus high stormwater runoff), the combined sewage-stormwater mixture overflows from the pipes before reaching a treatment facility. CSOs are designed to dump into the Willamette River, but can also result in sewer back-ups in the basements of some unfortunate homes. Taylor 18

Criticisms of Portland Stormwater Policy

The stormwater management practices being implemented in Portland are considered to be some of the most advanced and forward thinking in the nation when it comes to new development. Portland stormwater policy has successfully moved beyond the commonly held criticism of stormwater management as being too focused on large structural devices that focus on flood prevention, and “rarely incorporate features that promote infiltration (799)” (Dreelin et al. 2006). Yet, according to both the writers and practitioners (i.e., builders) of the stormwater management policy, it is not without flaw.

According to Steve Fancher of Gresham’s BES, the most common criticism of

Portland’s stormwater policy is that it applies only to new development, and in doing so ignores the high volume of stormwater being produced by development that is already in place (2006).11 In order to address this issue, various government sponsored organizations, such as BES’s Sustainable Stormwater group and Metro’s Green Streets

Program, are working with residents to obtain funding for retrofits that would update or replace existing stormwater systems. These programs, in addition to incentives of reduced residential sewer bills for home owners that reduce stormwater inputs, work to lower the volume of runoff that enters overburdened streams and stormwater/combined pipes alike (Fancher 2006).

A second criticism is that current stormwater management practices require pollution reduction and infiltration to occur on the source site (i.e. the lot or single property), thereby preventing the construction of neighborhood stormwater systems that could potentially reduce costs for the builder, and increase the amount of retention

11 Steve Fancher, now of Gresham BES, led the last stormwater policy revision when he was still with Portland BES in 2004. Taylor 19 occurring within a given development (Castaneda 2006). This issue will be addressed in more detail in the next section as a possible alternative for increasing surface infiltration in the Tryon Creek watershed.

Third, some professionals and citizens find themselves skeptical as to whether stormwater systems do what they are supposed to do. According to Fancher, “there are not any post-development monitoring requirements” for built stormwater systems, and therefore “flow control regulations are strictly designed-based rather than performance based” (2006). There is a possibility, therefore, that even the most well designed system could fail to control runoff when put into practice. This worry is further substantiated by the lack of personnel at BES to keep track of the stormwater facilities being built and to guarantee their maintenance (Fancher 2006). In addition, it is the already over-burdened building inspectors, not stormwater professionals that are required to inspect and approve stormwater design. This practice has resulted in the occasional approval of systems that may in fact not be built correctly (Fancher 2006). These missteps are rarely, if ever, intentional and are merely reflect an ambitious but overtaxed system.

Runoff (Flow) Control Policy

While human health and public safety represent important concerns, much of

Portland’s stormwater policy centers on the reestablishment of normative flow conditions to support salmonids and/or other native species through the maintenance of essential habitat (Actions for watershed health 2005). In order to accomplish this goal, city policy mandates that the peak-flow runoff (i.e. the maximum discharge, or maximum volume of water per unit of time) from a given site after development has occurred should not Taylor 20 exceed that of the pre-development peak-flow runoff. By ensuring that the amount of water entering the stream system per unit time does not increase after development, the city hopes to avoid stream bank and channel erosion, and subsequent habitat degradation.

Runoff from sites of development is limited in one of two ways. First, stormwater can be collected during storm events, temporarily stored, and slowly released from large subsurface vaults and/or pipes, known as detention facilities. Second, stormwater management systems can promote stormwater retention, where the site “keeps” a portion of the water through surface infiltration or evapotranspiration, thereby releasing less stormwater from a site. Though both of these systems work to “lessen [the] downstream impacts (1-30)” of increased runoff volumes, retention (i.e. on-site infiltration) is the more desirable of the two methods, as it better mimics natural hydrological conditions, and ensures groundwater recharge (Stormwater management manual 2004). Therefore, on-site infiltration is required to the “maximum extent practicable,” or that which is

“available and capable of being done…after taking into consideration cost, existing technology, and logistics in light of the overall project purpose (1-12)” (Stormwater management manual 2004). On-site infiltration systems might employ infiltration planters, permeable (or pervious) pavement, or grassy or vegetated swales (or infiltration basins). All of these systems collect runoff and/or rainfall, providing a “safe” location for that water to be infiltrated through subsurface soils and into groundwater reserves.

If on-site infiltration is deemed impractical, other retention systems that maximize evapotranspiration and provide pollution reduction are required (Stormwater management manual 2004). These facilities might include permeable pavement lined with concrete, flow-through planter boxes, or lined bioswales that prevent runoff from being fully Taylor 21 infiltrated. These systems trap runoff and rainfall, allowing for limited evaporation or evapotranspiration before the runoff is filtered through layers of gravel, sand, and possibly some sort of filter fabric. Runoff is allowed to infiltrate through these layers to remove pollutants, but the process is stopped (usually by concrete lining) a few feet below the surface. Runoff is then piped to detention vaults or large detention pipes, where it is stored for later release into streams.

Sites that cannot fully retain their stormwater must direct runoff offsite into ditches, streams, rivers, or off-site sewers (Stormwater management manual 2004).

Though unable to retain stormwater, these sites still must comply with policy that requires stormwater to be detained for a minimum 24 hours before being released into these “conveyance” systems. Though these management priorities of retention first, detention second may seem relatively clear at the outset, such priorities become increasingly muddled when put into practice.

Stormwater Disposal Hierarchy

In order to determine the degree to which detention and retention facilities must be put in place at any given site, a developer or designer will turn to the Stormwater

Disposal Hierarchy located in the Stormwater Management Manual. This Hierarchy is used to “determine the ultimate discharge point” of stormwater runoff, whether that be the soil (i.e. retention), a detention facility for later release into the creek, or a combined sewer. The Hierarchy contains four disposal options in order of most to least desirable. If Taylor 22 evidence of a particular “condition” prevents the implementation of a more desirable option, the next, less desirable option is chosen.12

The first option for stormwater disposal is “onsite infiltration with a surface infiltration facility.” Sites are exempt from this disposal technique if the soils do not infiltrate at the minimum rate of 2-inches/hour, which includes nearly all “projects on the

West side of the Willamette River (1-18)” including those in the Tryon Creek watershed

(Stormwater management manual 2004). According to Steve Fancher, this infiltration rate is primarily in place to prevent the construction of structures that would require frequent maintenance (Fancher 2006).

Long ponding times (i.e. those created when the infiltration rate is less than

2inches/hour) are caused by soils of low permeability, and in the case of the Tryon Creek watershed, are an indicator of soils dominated by fine silt and clay. When stormwater enters an infiltration facility, these fine-grained soils settle out of suspension, coat the infiltration surface, and slow, and eventually stop, the infiltration of additional stormwater. Long-ponding times can also lead to anoxic (oxygen-depleted) conditions that contribute to the formation of a layer of undecomposed plant material on the bottom of the infiltration facility (i.e. bioswale, etc.), which also limits infiltration after some time (Ferguson 1998). All stormwater facilities require some level of maintenance, but the continuous upkeep required in infiltration systems plagued by extended ponding is largely cost prohibitive (Fancher 2006).

Sites are also exempt from the requirement of on-site infiltration if stormwater infiltration may exacerbate possible slope instabilities at a site. The policy attempts to

12 See attached appendix for the complete disposal hierarchy. Taylor 23 minimize this possibility by preventing the construction of infiltration facilities on slopes exceed a 10% grade. According to those that design, permit, and build stormwater systems, the developer and/or the City are often the first to be sued if a damaging landslide occurs on someone’s property (Fancher 2006; Castaneda 2006). Property owners are quick to point a finger at poorly designed stormwater disposal systems as the mechanism for triggering these slides. Though legitimate in some cases, many sites in

Portland, especially in the West Hills, are simply prone to landsliding because development has taken place on steep, silt-covered slopes. Despite this, policy still exempts sites located within the steep and clay-rich (i.e. low permeability) Tryon Creek watershed from the requirement of on-site surface infiltration on both counts.

If a site is exempted from the requirement of surface infiltration, it is subject to the requirements of the second category of stormwater disposal- “on-site infiltration with a public infiltration sump system, private drywell, or soakage trench” (Stormwater management manual 2004). These facilities are dug into the ground, and therefore do not depend on the infiltration capacity of surface soils. Instead their effectiveness depends on the hydrologic conductivity of the surrounding soils. Like surface infiltration facilities, these systems are not allowed within sites whose subsurface soils do not infiltrate at the minimum rate of 2 inches/hour, or those sites with slope instability. These systems are classified as underground injection control structures (UICs) that must be permitted first by the DEQ.13 This lengthy process can make UICs an undesirable alternative for developers on a strict timetable (Castaneda 2006). This resource intensive process, in

13 By requiring infiltration structures deeper than five feet to be permitted, the DEQ is attempting to prevent the direct pollution of subsurface flow and groundwater reserves (Castaneda 2006). Taylor 24 addition to soil and slope exemptions, limits the installation of these below surface structures in the Tryon Creek watershed.

The most common stormwater management technique employed in the Tryon

Creek watershed is the third disposal option-“offsite flow to a drainageway, river, or stormwater sewer.” Though off-site flow prevents infiltration, some sort of pollution reduction technique and a detention facility is still required. For example, the Tryon

Highlands development, which is currently being built off of Boones Ferry Road near

Stephenson Road, employs a residential stormwater design that is standard across new development in the basin. This development is zoned for 7000 square-foot lots, upon which standard 2000 square-foot houses are to be built. According to the project leader,

Albert Castaneda of Alpha Community Development, precipitation that falls on this development will be directed to flow-through planters from roofs. These flow-through planters provide opportunities for evapotranspiration and pollution reduction. This runoff, in addition to runoff caught by catch basins that line the street, will be put into an underground vault for further pollution reduction and then transferred into a large detention pipe. These pipes store runoff for 24 hours after a storm event, at which point it is slowly released via another pipe onto the armored bank of a nearby stream channel.

While such practices successfully limit high velocity, erosive runoff from entering the stream channel directly, this required disposal option fails to address the hydrological and ecological need for greater infiltration, evapotranspiration, and groundwater recharge.

The “sensitivity of the water resource” (i.e. the destination) can be used to justify the employment of the final option- “offsite flow to combined sewers.” Concern for the health and safety of humans and wildlife after potential CSOs, make this the least Taylor 25 desirable location for disposal, and is rarely, if ever, justified. Thus, when the policy hierarchy is employed to determine the location of stormwater disposal in the Tryon

Creek watershed, the option with the greatest impact on the channel (option 3) is the only disposal technique allowed.

Therefore, given the inability of current stormwater policy to effectively increase the retention of runoff onsite through infiltration in the Tryon Creek watershed, we must look for potential changes in policy that would better fit with the constraints posed in this location. If the restoration of the Tryon Creek watershed is to succeed in the long run, the policy will need to become more effective at dealing with runoff at its source. In order to succeed in accomplishing this task, policy must move beyond concerns of erosive high flows, which can be largely dealt with via detention facilities, and start to better address the potential problems associated with limited on-site infiltration as well.

III. Infiltration Alternatives in the Tryon Creek Watershed

Fear of potential financial liability, held by the City and builders alike, has lead to a strict interpretation of stormwater policy that has discouraged builders from attempting to infiltrate even small volumes of runoff.14 Though not intentionally, the current implementation of stormwater policy leads to an all or nothing scenario, where if it is deemed unsafe to infiltrate any runoff on-site, then no infiltration is allowed. Those that work at BES recognize this problem and recently funded a study to locate areas within

14 Groundwater recharge does not require the complete infiltration of every large storm. It can be accomplished by infiltrating a portion of the precipitation delivered to the system in low intensity, frequent storm events (Ferguson 1998). Taylor 26 the Tryon Creek watershed where surface infiltration can be increased (Savage 2007).15

In the following sections I will explore four ideas for increasing the retention of stormwater produced by current, and yet to be constructed, development: 1) community- scale stormwater systems, 2) decreasing ones impervious “footprint,” 3) forested buffers, and lastly, 4) early site planning.

Community-scale Systems: A case study of SW Texas Street

One technique for increasing infiltration would involve a reworking of the policy that requires a house-by-house approach to stormwater management. This “microscale” focus, introduced with the last policy revision in 2004, was intended to promote citizen engagement by placing responsibility for stormwater production on the homeowners individually, as opposed to the City, larger community, developer, etc. (Fancher 2006).

This policy requires homeowners to maintain the stormwater facilities on their property.

According to Fancher, limited manpower and money at BES often result in a failure to communicate detailed maintenance instructions to property owners (2006). Without proper maintenance, these small stormwater systems (i.e. bioswales, flowthrough planters, etc.) can quickly become ineffective, and possibly forgotten.

An alternative might be a structure that filters, retains, and detains the stormwater produced by an entire neighborhood. For example, a wetland or pond could be

15 This study, performed by Portland-based firm Golders Associates Inc., attempted to identify the spatial extent of a layer of extremely low-permeability (known as fragipan) that is supposed to be found throughout all Cascade-series soils. Through extensive borehole analysis, the study concluded that though fragipan was not necessarily as “ubiquitous” as previously claimed, there was no consistent pattern in its distribution. Though this study failed to identify large swaths of land into which surface infiltration facilities could be successfully installed, it did provide some hope that such locations may exist (Tryon and Fanno Creek watersheds borehole log analysis report 2007). Taylor 27 constructed that would be publicly owned and maintained by the city, or privately owned and maintained by a community. According to developer Albert Castaneda, building such community stormwater “sinks” on undeveloped tracts of land, instead of costly individual structures on-site, could reduce the cost of development (2006). These savings could then be invested in the long-term maintenance of the structures. While stormwater professionals are unsure of the relative effectiveness of such community-based versus individual site-by-site structures,16 consistent and correct maintenance seems more likely to occur in the former, as the city and/or community would be responsible for a single, visible structure.

While the above policy change would apply to all new development, existing developments could also benefit from the installation of neighborhood stormwater management systems. It is often difficult and costly to build infiltration systems on ones personal property, and nearly impossible to get them permitted in the Tryon Creek watershed (Manning 2006), so these larger systems seem like the only option. While examples of these larger facilities are hard to come by in the Tryon Creek watershed, a system of ponds is currently being constructed as a part of the SW Texas Green Street project in the nearby Stephens Creek watershed.

SW Texas Street is located between the SW Portland neighborhoods of Hillsdale and Multnomah Village, and became the site of a Metro sponsored “Green Street” after a multi-year effort by (and between) property owners to get the unimproved street paved

16 There is an exciting study occurring in the newly redeveloped neighborhood of High Point in West Seattle that will attempt to address the relative efficiency of these two approaches in reducing the peak flow of runoff from a site, as well as the success of each approach in reducing pollutant load. The results of this study can be used to judge the appropriateness of this possible policy change. Taylor 28 and curbed by the City. The Green Street Program, which has retrofitted streets in downtown and east Portland, attempts to “integrate a system of stormwater management within its right of way,” through the installation of retention and detention facilities (e.g. swales, etc.) and the planting of street trees in parking strips to maximize interception and infiltration of rainfall (Green streets 2007).

Despite having similar low-permeability soils and steep slopes as in the Tryon

Creek watershed, SW Texas Street was considered by BES and Metro a good candidate for a Green Street project. The unpaved street acts as a collecting point for a large portion of the runoff produced in this small watershed, which then drains directly into Stephens

Creek. After large storm events, runoff has created streams that washed away large sections of the gravel street. Not only did this frustrate those living on SW Texas Street, the runoff also had little opportunity to infiltrate before high volumes of fast moving, pollutant-laden water entered the stream. This frustration inspired neighborhood advocates to pursue improvements that would prevent further property damage. The neighbors and the City developed a plan that would turn a vacant lot at the bottom of the street into a large-scale detention/retention site and greenspace.

For this project to occur, the neighborhood was first designated a local improvement district, or LID, by the city. This allowed the community to “tax” homeowners to fund the paving of the street. 17 Then the neighborhood was able to obtain funding for the design and installation of swales as pollution reduction facilities that will border the steeply sloping street. Concerns that the infiltration of runoff into soils below the street swales might cause basement flooding or aggravate slope instability led to the

17 The size of the contributions varies depending on the lot size of each property. Taylor 29 decision to pipe the captured runoff into constructed storage ponds on the land purchased by BES. These ponds will allow for evaporation, limited infiltration, and detention, all of which will reduce peak stream flows immediately following storm events.

Because nearly 15% of all lots in the Tryon Creek watershed are currently deemed vacant, this community-based approach to stormwater management could be a very real possibility for local neighborhoods (Fanno and Tryon Creeks management plan

2005). Though this is an exciting opportunity, there are some limitations to the widespread adoption of these structures. For example, it took the residents of SW Texas

Street three years to get their Green Street plan developed and approved. Though they were finally successful in obtaining funding, despite considerable reservations in both

BES and the Portland Department of Transportation (PDOT) on the feasibility and maintenance of these structures, Dan Manning, a SW Texas Street resident and leading project advocate revealed that navigating the city bureaucracy was often exasperating. As this was such a resource intensive effort Manning believes that this solution might not be applicable in all situations or within all communities. Fancher echoed and expanded on this latter view, claiming that it is difficult, if not impossible, to successfully create an

LID or Green Street for the sole purpose of stormwater management. Instead neighborhoods must illustrate additional motivations to obtain funding, such as the paving of a street, or the construction of sidewalks. Such partnering could potentially play an important role in the Tryon Creek watershed, as over half of its streets are uncurbed, and nearly 13 miles are completely unimproved (i.e. unpaved, no sidewalks, no storm drains, or catch basins) (Fanno and Tryon Creeks management plan 2005). Taylor 30

Decreased “Footprint”

Incorporating a community-based view of stormwater management into current

Portland policy could be complemented by a move to provide more incentives to homeowners and developers to decrease the “footprint” (as measured in impervious area) on their property. While this could involve decreasing the sizes of homes built in the

Tryon Creek watershed, decreasing ones impervious footprint could also involve the installation of semi-permeable structures, such as ecoroofs or permeable pavement. While developers are given incentives to install ecoroofs and permeable pavement, these techniques can be prohibitively expensive or risky, in the case of ecoroofs, or simply too new of a technology, in the case of permeable pavement, for widespread use as of yet

(Castanda 2006; Fancher 2006). According to Fancher there are few substantial incentives for these techniques to be employed by private homeowners, and it is therefore unlikely that they will be able to afford the costs associated with the correct installation of these structures on their own.

Though not yet widely employed, permeable pavers represent an interesting opportunity for increasing surface infiltration. The installation of permeable pavement does not require builders or homeowners to dedicate valuable portions of their property to stormwater systems such as bioswales, detention ponds, or flow-through planters.

Instead, the pavers merely replace existing (or are installed instead of) impermeable surfaces, such as concrete or asphalt.

Permeable pavement consists of paving stones made of a permeable plastic or concrete matrix that overlie layers of high porosity material (e.g. gravel with lots of storage space between grains) and filter fabric used for pollution reduction (Stormwater Taylor 31 management manual 2004); any open spaces between “stones” are filled with sand or gravel, and possibly grass. These systems are most commonly used in low-traffic areas such as driveways, patios, parking lots, etc., as opposed to high-traffic public streets.18

Like other surface infiltration facilities, these systems are limited to areas whose soils infiltrate at a rate of at least 2 inches per hour, and whose slopes do not exceed 10%.

Given these policy limitations, areas like the Tryon Creek watershed cannot infiltrate the rain that falls on permeable pavement if it is installed. If, instead of this all-or-nothing scenario, the policy allowed for a portion of the rainfall to be infiltrated, areas like Tryon might be able to increase infiltration in a dispersed manner over the entire permeable surface (i.e. avoiding the concentration of infiltrated water that could aggravate slope instabilities). In fact, a recent study indicated that permeable pavement can be “used effectively on clay soils for the control of small storms and the retention of the ‘first flush’ during larger storms (803)” (Dreelin et al. 2006).

Though a promising opportunity, infiltrating just a portion of the rainfall would require a completely new design. Currently, when infiltration systems are installed in areas such as the Tryon Creek watershed they must be lined with some impermeable structure (e.g. concrete, etc.) to prevent the complete infiltration of runoff. This is done mainly to prevent the infiltrating water from triggering landslides or causing basement flooding. Employing infiltration systems, such as permeable pavers, in the Tryon Creek watershed would require most of the infiltrated water to be piped out of the system into

18 PDOT has not approved the use of permeable pavers in public right-of-ways due to concerns with maintenance, including sedimentation that accounts for 69% of this techniques failures and the compaction of underlying materials in areas that experience consistent traffic (Dreelin 2006; Fancher 2006). While maintenance costs are not likely much higher than that required for concrete or asphalt streets, the maintenance of permeable pavers requires different machinery that may have high upfront costs. Taylor 32 some detention facility, as is currently done, while leaving a portion behind for complete infiltration into groundwater reserves. In adopting such as design, builders and property owners minimize risks of aggravating slope instabilities, while simultaneously reducing runoff from their site by recharging groundwater reserves.

Forested Buffers

Instead of dumping stormwater directly into the streams of the Tryon Creek watershed, some have proposed releasing stormwater into forested buffers, where runoff may slow and infiltrate before entering streams (brush 2006). Forested buffers have been shown to be beneficial when planted along roadsides to capture, infiltrate, and filter runoff (Matteo et al. 2006). These buffers would not only increase interception, they often promote higher infiltration rates than their constructed counterparts (i.e., bioswales, ponds) and can greatly reduce runoff (Matteo et al. 2006). By reducing runoff to streams, these buffers reduce channel erosion and provide locations for infiltration to groundwater reserves. For lands that include a stream, this stormwater can be dispersed into its associated riparian buffer, and for those that do not, stormwater can be directed in adjacent or nearby sections of forested public park, or possibly on private property.

The dispersal of stormwater runoff into forested buffers does raise concerns about generating slope instabilities. This possibility can be minimized if the runoff is dispersed on the flatter terraces associated with relic or active floodplains. If this stormwater were to be dispersed at the surface, there is also some concern that the points of dispersal could promote erosion that could lead to the formation of small streams or gullies. If stormwater were instead released underground through perforated pipes, this potential Taylor 33 erosion could be avoided. Within these buffers one would not have to worry about the infiltration rate, as these more intact ecosystems would not need continual maintenance.

There are two main impediments to the implementation of this idea. First, the water table in riparian locations is already high and therefore any water infiltrated will likely be immediately discharged into the stream upon reaching the groundwater table, and not remain in storage for base flow during the dry season. Second, the costs associated with installing perforated pipes along the length of the entire forested buffer may prohibit wide implementation.

Early Site Planning

All of these possibilities for increasing infiltration will likely dramatic improvements in site planning if they are to be implemented in new development. This would require the inclusion of BES early in the site planning process to 1) assist builders in identifying the most promising locations for infiltration, and 2) limit the negative impacts of certain site preparation techniques on its hydrologic or ecologic “health.”

Fancher revealed that increased oversight is often considered a “political hot potato,” as it would involve a “hands-on approach [by BES] to [the] private development [of] stormwater management design” (2006). Such a hands-on approach might put restrictions on certain construction methods to limit soil compaction and soil cuts, protect the tree canopy, or require the importation of topsoil that best assist with infiltration (Fancher

2006). Such involvement may also force developers to dedicate some of their most valuable lots for the installation of costly infiltration systems. Taylor 34

Though early site planning would likely be the most effective approach to increasing surface infiltration in the Tryon Creek watershed, its implementation would face many challenges. First, there is the logistic difficulty in getting BES officials on-site early in the planning phase. Currently, BES usually comes into the picture when stormwater system designs are brought to the Bureau for approval. At this point, the developer has already completed a layout of their development and has likely begun preparing their site for construction. According the Fancher, there are no procedural steps in place to alert BES of a new development before the submittal of stormwater designs, therefore getting involved early in the planning phase will be challenging. Second, early oversight would require greater flexibility within BES in terms of its interpretation of stormwater policy. Such flexibility will require a staff of well-trained individuals with a deep understanding of the limits and points of leverage within the policy. This is difficult to attain with a small staff of three to four people that is required to review and judge all of the City’s incoming stormwater system designs. Fancher believes that this limited staffing results in a rigid interpretation of the policy, as these individuals do not have the time or resources to verify the appropriateness of a given design in the field (2006). The first step to increasing flexibility is to increase staff power, which will require increased finding for BES. This funding requires a proof of need that would, in my opinion, be best illustrated by pointing out the stark disconnect between the stated goals of policy and current practices.

In addition to exploring alternative policies that could promote increased surface infiltration, as done above, it is also important to address the possibility that current Taylor 35 stormwater policy might benefit from more realistic rhetoric, especially when concerning the Tryon Creek watershed. Current Portland stormwater policy is written to apply to the entire city, despite variation in the successful application of these practices across watersheds. Limited staffing, as well as geologic and financial constraints, has led to a rigid interpretation of stormwater policy that prevents even small volumes of rainfall from being infiltrated. This lack of infiltration raises concerns within the community of the Tryon Creek watershed about channel erosion and long-term summer base flow.

Fear of financial liability for basement flooding and landslides, as well as cost of maintaining these onsite infiltration facilities given the geologic context make it unlikely that infiltration will be increased dramatically from current levels. Given this observation, the Tryon Creek watershed would benefit from site-specific stormwater management policy that clearly outlines the limitations facing the reestablishment of “normative” flows. In general, community members are not fully aware of the legitimate geologic constraints and financial fears that inform the current implementation of stormwater policy in their watershed. Without educating about the limitations facing infiltration, the community knows only to accuse BES of stormwater policy full of loopholes that benefit developers. There is no doubt that BES is responsible for managing stormwater, and that currently, in my opinion, they are failing to limit stormwater inputs into Tryon Creek and its tributaries. But blaming BES distracts from positive strides that can be made in acknowledging the limitations facing the restoration of hydrologic and ecologic processes in the Tryon Creek watershed.

Despite the inability to completely reestablish infiltration pathways in this watershed, work is currently being done to improve habitat for the rehabilitation of native Taylor 36 salmonid and lamprey eel populations. In the final section of this paper I explore the implications of the current stormwater policy as it is applied in the Tryon Creek watershed on these and future restoration efforts.

IV: Current Habitat Restoration Efforts in the Tryon Creek Watershed

In Portland, land and water are elemental, the very icons of the city. The rain, our regions rivers, and out land – the watersheds that gather, feed, and protect them – are our identity, the essence of who we are and where we’ve come from. Chet Orloff, Portland Parks Board

The above quote, taken from the introductory pages of Portland’s watershed management plan, Actions for Watershed Health, exemplifies the passion that drives many of those that work to restore the City’s watersheds (2005). Though the desire for

“healthy” watersheds in the Portland landscape is unambiguous, the ways that we talk about “restoring” them are much more nuanced.

The Oxford English Dictionary defines “restoration” as the act of “bringing back to the original state.”19 On their website, BES promotes projects that “restore” or

“improve” watershed health (Watershed Health 2007). While the former seems to follow the Oxford definition, the latter does not connote such a complete reversal of damage.

The Friends of Tryon Creek State Park, a small non-profit organization operating within the bounds of the TCSNA, outlines goals to “conserve and enhance natural resources,” as opposed to their complete “restoration” (Friends of Tryon Creek state park 2006). The

Portland Endangered Species Act Program, formed after the 1998 listing of steelhead as

“threatened” under the federal ESA, provides the third and most detailed description of

19 Second edition. 1989. Accessed at http://dictionary.oed.com (March 2007). Taylor 37

“restoration” of the Portland’s watersheds. This organization attempts to coordinate efforts within the City to “protect and restore properly functioning habitat conditions throughout its watersheds to support abundant, self-sustaining populations of native fish”

(Watershed management 2007).

These differences in goals illustrate a diverse set of understandings of what it means to “restore,” from bringing watershed health back to its original state, to more generally improving or enhancing habitat, to the maintenance of self-sustaining populations of salmonids. So what exactly do we mean by “restoring” the Tryon Creek watershed? Is our goal to turn back the clock and bring the watershed back to its original state, or is it to improve or enhance habitat? And what is the final goal of this enhancement?

Recent restoration efforts in the Tryon Creek watershed have focused on in- channel stream habitat, despite the continued hydrological change promoted by increasing amounts of runoff from surrounding development. Some of the largest of these projects are initiated by the discovery of undermined or exposed sewer lines in Tryon

Creek. These projects, including one funded by the National Oceanic & Atmospheric

Association (NOAA) in 2005 near SW 4th Avenue, combine bank stabilization techniques to prevent continued erosion and possible breakage of exposed sewer lines, with the improvement of salmonid spawning habitat (Tryon Creek 2007). The Friends of Tryon

Creek State Park are also working on in-channel habitat improvements with the installation of multiple brush check dams in the tributaries of Tryon Creek to slow flows and capture fine sediment. Again, this work is being done for the “restoration” of native Taylor 38 salmonids, as well as lamprey eel species, through the improvement of spawning and rearing habitat (Peterson 2006).

Other projects include the daylighting (i.e. bringing to the surface) of a previously piped section of creek in the headwaters of the watershed, as well as the planned removal and/or retrofitting of multiple culverts within the park (Leeson 2006; Peterson 2006). The most significant of these culvert projects will involve the retrofitting of the Macadam

Culvert, located under Highway 43, near the confluence of Tryon Creek and the

Willamette River. The retrofits currently planned will involve the installation of in- channel structures that will increase stream flow through the culvert to allow for fish passage. Eventually the hope is to remove the culvert altogether and replace it with a bridge.

Restoring in-channel habitat makes sense if “some impacts from construction and urbanization with the watershed have stabilized (4-10)” (Fanno and Tryon Creeks management plan 2005). According to tax lot records, nearly eighty-percent of available land in the Tryon Creek watershed has been “built-out.” Future growth will likely occur via infill development, and is thus unlikely to dramatically increase impervious surfaces such as roads, etc. (Fanno and Tryon Creeks management plan 2005). Though hydrological impacts may indeed be stabilizing, the watershed is a very different system than it once was. The system has always been steep and small, with low permeability soils, and a somewhat flashy hydrology. But its hydrology, and therefore its channel and hillslope geomorphology, has been changed by human development. These abiotic changes, including the installation of fish passage barriers and the increased pollutant load from runoff, have initiated a cascade of biotic impacts that have also dramatically Taylor 39 changed the composition of the aquatic communities. This is most clearly evidenced by the steep decline in salmonid and lamprey abundance in the watershed.

Given these changes, it is important that practitioners of restoration refrain from uncritically embracing the popular belief that if build the habitat, they, the salmon, will return. There are countless examples of river and stream restoration projects that failed, at times catastrophically, due to the assumption that one could mold the channel into what is used to look like, or what the community/practitioner/city wishes it looked like, and that it would in turn behave in this way (Booth 2005; Brady 2007). In-channel restoration techniques such as the installation of large woody debris (LWD), or the importation of sediment for gravel bars, or the revegetation of riparian zones, often follow this line of reasoning. Though these efforts are well intentioned, and sometimes successful, it is essential to remember that form follows function in a stream system, and not the other way around. Therefore, the restoration of a stream’s morphology or the revegetation of its banks and floodplains, may fail to create a salmonid supporting channel because it does no address the dominant factors that affect “biotic health” (Booth 2005).

The shortcomings of these in- or near-channel improvements must be addressed when deciding whether or not to spend millions of dollars on restoration projects. The

Longfellow Creek restoration project in West Seattle provides an object lesson. This project spent close to eight million dollars on in-channel rehabilitation efforts, including large woody debris and gravel placement, riparian revegetation, and the removal of fish passage barriers, in an attempt to mitigate the effects of dense urbanization (Booth 2005).

Despite restoring the physical structure to the channel, the project ultimately failed in its goal to restore salmonids to the system, because of watershed-scale biotic issues (i.e. Taylor 40 pollutants, etc.) that resulted in “massive pre-spawning death” of returning salmonids

(Booth 2005). In order to avoid this mistake, those that are working to restore the Tryon

Creek watershed must address the possibility that altered hydrologic patterns in the basin, as well as the increased pollutant load, might make salmonid restoration impossible.

Addressing this possibility, however likely or unlikely, will help to discourage a management plan that is unrealistically optimistic, and will lead to more appropriate and effective decision making.

I do not wish to inspire fatalistic perspective on restoration efforts in the Tryon

Creek watershed. Measured optimism does not necessitate the adoption of a completely pessimistic view. Restoring this watershed to support pre-development salmonid populations would likely require the adoption of difficult and costly stormwater management practices beyond the current scope of the policy. Nevertheless, restoration efforts can and should continue with the acknowledgement of additional motivations beyond the return of salmon. The aesthetic desire to have Tryon Creek look and function in a way that mimics a natural system (though not necessarily in the same way as the

Tryon Creek watershed did pre-development) is one valid motivation for restoration. A desire to repair quickly eroding banks, turbid flows, and naked floodplains for purely aesthetic reasons can inspire a community to action just as strongly as a desire for aquatic biodiversity. Another motivation for restoration mentioned in the City’s watershed management plan is to enhance “livability” or “appropriate human access to the natural environment (41)” (Actions for watershed health 2005). These goals still entail in- channel restoration, but not necessarily for the sole purpose of salmonid rehabilitation. Taylor 41

In expanding our motivations for restoration to include other valid goals, the movement for watershed restoration and effective management will be strengthened.

However, restoration efforts will continue to be at risk if watershed-scale concerns are ignored and in-channel restoration remains the main focus. There is evidence that the scope of stormwater management in the Tryon Creek watershed is beginning to incorporate larger-scale runoff management strategies. In one example, BES partnered with Jackson Middle School, located in the Arnold Creek neighborhood, to replace impervious surfaces with swales that slow, infiltrate, and filter runoff (Tryon Creek watershed 2007). Another project, completed in the summer of 2006, transformed a vacant lot at 17th and Taylor’s Ferry Road into a large swale and water quality monitoring facility. BES also sponsored the removal of a 3100 square foot concrete basketball court located only fifteen feet away from Tryon Creek (Tryon Creek watershed 2007). If those that support and/or perform restoration in the Tryon Creek watershed continue to demand such large-scale projects, whose innovative designs attempt to address all of the problems associated with urban development, in-channel restoration projects will be much more successful.

Before more resources are invested in this watershed however, it is important that the actors involved in the Tryon Creek watershed have a frank discussion to articulate the legitimate goals surrounding restoration, and to recognize the economic and hydrologic/geologic constraints associated with the full implementation of stormwater policy needed to fulfill these goals. This discussion is especially appropriate for groups such as BES, or the Friends of Tryon Creek State Park, who are currently implementing a majority of the restoration projects. I believe that such conversations are best suited to Taylor 42 take place during the monthly meetings of the Tryon Creek Watershed Council, as they include stakeholders with a variety of backgrounds that advise “local and regional government planning, assessment, monitoring and preservation initiatives” (Tryon Creek

Watershed Council 2007). By reevaluating the goals for restoration in light of the constraints on current stormwater policy, the Council, the Park, and BES will be able to more effectively manage this watershed into the future.

Taylor 43

Works Cited:

Actions for watershed health: 2005 Portland watershed management plan. 2005. Portland, OR: Bureau of Environmental Services, Available at http://www.portlandonline.com/bes/index.cfm?c=38965&a=107808 (accessed October 24, 2006).

Booth, Derek. 2005. Challenges and prospects for restoring urban streams. Journal of the North American Benthological Society, v. 24, p. 724-737.

Brady, R. 2007. Open Channel Restoration for Aquatic Habitat. Geology 280 (lecture given February 22, 2007), Lewis & Clark College, Portland, OR. brush. 2006. personal interview with author, September 9, 2006. Try/on Life Community Farm, Portland, OR.

Castaneda, Albert. 2006. personal interview with author, October 4, 2006. Alpha Community Development, Project Manager, Beaverton, OR.

———. 2006. email correspondence with author, October 18, 2006. Alpha Community Development, Project Manager, Beaverton, OR.

Devereaux, MG. 2006. personal interview with author, October 17, 2006. Tryon Creek State Natural Area, Park Manager, Portland, OR.

Dreelin, Erin A., Laurie Fowler, and C. Ronald Carroll. 2006. A test of porous pavement effectiveness on clay soils during natural storm events. Water Research 40, (4): 799-6.

Dunne, Thomas, and Luna B. Leopold. 1978. Water in environmental planning. New York: W.H. Freeman and Company.

Fancher, Steve. 2006. personal interview with author, October 24, 2006. Bureau of Environmental Services, Gresham, OR.

———. 2006. email correspondence with author, December 6, 2006. Bureau of Environmental Services, Gresham, OR.

Fanno and Tryon Creeks watershed management plan. 2005. Portland, OR: Bureau of Environmental Services. Available at http://www.portlandonline.com/bes/index.cfm?c=edajh& (accessed October 24, 2006).

Fanno and Tryon Creek watersheds borehole log analysis. 2007. Golder Associates Inc. Bureau of Environmental Services: Portland, OR.

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Ferguson, Bruce. 1998. Introduction to stormwater: Concept, purpose, design. New York: Wiley.

Friends of Tryon Creek state park. 2006. Portland, OR. Available at http://www.tryonfriends.org/ (accessed November 10, 2006).

Gaskill, Amy. 2006. News Release. United States Fish and Wildlife & National Fish and Wildlife Foundation. October 5, 2006. Available at http://www.fws.gov/pacific/news/2006/PNWNativeHabitatGrantsNR.pdf (accessed March 23, 2007).

Green streets: Innovative solutions for stormwater and stream crossings. 2007. Metro, Portland, OR. Available at http://metro.region.org/article.cfm?articleID=262 (accessed March 20, 2007).

Leeson, Fred. 2006. Project puts a new creek in an old bed. The Oregonian, In Portland. November 9, 2006.

Manning, Dan. 2006. personal interview with author, October 18, 2006. SW Texas St. LID, community member, Portland, OR.

Matteo, Michelle, Timothy Randhir, and David Bloniarz. 2006. Watershed-scale impacts of forest buffers on water quality and runoff in urbanizing environment. Journal of Water Resources Planning and Management 132, (3) (2006-06-00): 144-152.

Peterson, Robin. 2006. Tryon creek watershed trout and lamprey restoration project. Friends of Tryon creek watershed. Vol. 67744. Portland, OR.

Quinn, T.P. 2005. The Behavior and Ecology of Pacific Salmon and Trout. American Fisheries Society in association with The University of Washington Press, 378 pp.

Reiser and Bjornn. 1976. Habitat requirements of anadromous salmonids. Portland, OR: Pacific Northwest Forest and Range Experiment Station. 54 pp.

Savage, Gregory. 2007. email correspondence with author. January 29, 2007. Bureau of Environmental Services, Portland, OR.

Stormwater management manual. 2004. 3rd ed. Portland, OR: Bureau of Environmental Services. Available at http://www.portlandonline.com/bes/index.cfm?c=35117 (accessed September 2006).

Sustainable Stormwater. 2006. Portland, OR: Bureau of Environmental Services. Available at http://www.portlandonline.com/BES/index.cfm?c=34598 (accessed September 2006).

Tryon creek watershed. 2006. Portland, OR: Bureau of Environmental Services. Taylor 45

Available at http://www.portlandonline.com/bes/index.cfm?c=32200 (accessed November 10, 2006).

Tryon Creek watershed council. 2007. Portland, OR. Available at http://tcwc.tryonfriends.org. (accessed April 25, 2007).

Upper Tryon creek corridor assessment. 1997. Portland, OR: Bureau of Environmental Services. Available at http://www.portlandonline.com/bes/index.cfm?c=43115&a=127706 (accessed January 26, 2007).

Urban growth boundary. 2006. Portland, OR: Metro. Available at http://www.metro- region.org/ (accessed February 12, 2007).

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Appendix:

Stormwater Disposal Hierarchy

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