Study Area Summary August 2017 Fanno Creek Study Area

Existing Conditions Fanno Creek flows from the hills of Many sections of are intact Steelhead trout, coho salmon, and southwest Portland through Beaverton while elsewhere historic development cutthroat trout are known by and Tigard to the . The approaches the stream. Several older Department of Fish & Wildlife to use study area within Tigard is 3.75 sq. mi. bridges restrict the floodplain. The Fanno Fanno Creek. Beaver are active from Greenway Trail follows the creek. Scholls Ferry Road to the mouth. Much of The basin is highly urbanized and sends the Fanno Creek corridor is listed as Class runoff to the creek very quickly during Beneath the creek, a sewer transmission I habitat in the Metro’s Title 13 Inventory storms. Despite these fast, high storm line runs to Clean Water Services’ of critical wildlife habitat. flows, Fanno Creek is notable for its lack Durham Wastewater Treatment Plant. of significant flooding problems. The Sewer trunk lines follow Fanno Creek’s creek’s wide floodplain helps prevent tributaries and tie into the transmission Hiteon Creek flows into Fanno Creek flooding of structures and roads. line. continued on back page Issues and Risks Proposed CapitalStrategies Improvement and Solutions Projects The Stormwater Master Plan assessed affect threatened fish, other wildlife, and Because Fanno Creek is already fully Proposed CIPs the risk of in Tigard’s streams. humans. urbanized, the strategy in the study area The assessment analyzed the likelihood is to mitigate for existing developed Fanno Creek Stream Stabilization at of erosion based on stream geology and Beneficial uses of spawning and rearing conditions. The many locations where Arthur Court the consequence of erosion based on the for threatened steelhead, which require the floodplain is still wide allow for a Rank: 8 CIP 410 stream’s proximity to important features cold water, are protected under the Clean strategy that is focused on increasing the North Dakota Street Stream such as roads, sewer lines, and buildings. Water Act through a Total Maximum resilience of the stream itself. Restoration and Detention Daily Load for temperature. Rank: 13 CIP 403 The assessment classified about 75% of Proposed stormwater capital projects in Total Cost: $1.7 million the Fanno Creek study area as medium Fanno Creek is important to the cities of Fanno Creek will protect channels from to severe for overall erosion risk. Of Portland and Beaverton, Metro Regional the erosive effects of fast, high flows the highest consequence is the danger Council, Clean Water Services, and ODOT. resulting from the basin’s geology and of undermining and breaking sanitary urban runoff. Protection of the sewer sewer pipes and undermining regional Fanno Creek’s regional significance transmission line, trunk lines, and the transportation infrastructure, including means there are numerous opportunities regional trail system is a primary driver of the regional trail. to partner with cities, service districts, the capital improvements. transportation agencies, and non-profits Fanno Creek is water quality limited to protect and restore natural resource The strategy for addressing water under the Clean Water Act for values while maintaining its functions quality in Fanno Creek focuses primarily phosphorus, bacteria, dissolved oxygen, as a stormwater conveyance and a on water quality in basins, and temperature. Poor water quality can transportation and utility corridor. discussed in other Study Area fact sheets.

Fanno Creek - page 1 - Fanno Creek Study Area

at Englewood Park. In 2009, several Creek, drain residential areas on the projects restored the floodplain and western edge of Fanno Creek between helped prevent channel erosion. Beavers the library and Bonita Road. They are are contributing to flooding of the trail located primarily on private property but are also slowing erosive flows and or in homeowner association common improving fish habitat. areas. These reaches have relatively intact channels. However, in steeper An un-named tributary to Fanno Creek sections erosion is beginning to isolate flows northeast below Hwy 99 and meets the channels from their . All Fanno Creek in downtown. Though small, three are head cutting where they meet this tributary is polluted with runoff from Fanno Creek. the highway and trash from commercial properties. The Methodist Church has attempted to restore the streambank near Frewing Street.

Three small tributaries, including Colony

Fanno Creek - page 2 - Study Area Summary August 2017 Red Rock Creek Study Area

Existing Conditions Red Rock Creek is at the eastern edge surface in the basin directing runoff to from the steep sections are transported of Tigard where commercial/industrial the creek unmanaged, stream flow in Red downstream and settle out in the flat buldings, box stores, office complexes, Rock Creek rises quickly during storms. In portions - blocking culverts and filling and three major transportation corridors heavy rain, the creek has been known to natural wetlands. dominate the landscape. The Tigard rise eight feet in 15 minutes. The effects Triangle, bound by I-5, Hwy 99, and Hwy of these fast high flows are exacerbated A sanitary sewer line runs the length of 217, is mostly located in the basin. The by constriction and alteration of the Red Rock Creek. The erosive forces of creek flows southwest into Tigard from a floodplain throughout its length. urban stormwater runoff have carved the densely developed part of Portland. The creek channel lower than the sewer line. study area within Tigard is 1.1 sq. mi. In the upper reaches, the creek flows When sections of the streambank fall through very steep terrain while lower into the creek due to erosion, they can With a significant amount of impervious reaches are quite flat. Eroded soils continued on back page Issues and Risks Proposed CapitalStrategies Improvement and Solutions Projects The Stormwater Master Plan assessed is water quality limited under the Clean A primary strategy is to support re- Proposed CIPs the risk of erosion in Tigard’s streams. Water Act for phosphorus, bacteria, development in the Tigard Triangle, SW Dartmouth Regional Wetland The assessment analyzed the likelihood dissolved oxygen, and temperature. which will bring existing developed Detention Pond of erosion based on stream geology and properties up to current standards the consequence of erosion based on the Urban stormwater runoff is known to for runoff treatment and control. Use Rank: 5 CIP 501 stream’s proximity to important features carry metals, nutrients, and bacteria to of small Low Impact Development Red Rock Channel Stabilization & such as roads, sewer lines, and buildings. streams. Red Rock Creek lacks shade Approaches to reduce competition for Sewer Protection where riparian canopy cover has been space is a key element. See the Tigard Rank: 12 CIP 506 The assessment classified about 50% reduced or removed. Shade from canopy Triangle Stormwater Implementation Knez Wetland & Riparian Enhancement Plan program for more details. of Red Rock Creek as medium overall cover effectively cools streams. Warm Rank: 15 CIP 505 erosion risk. A few spots are classified water can stress or kill cold-water fish Red Rock Floodplain Reconnection as moderately severe. The entire upper such as native salmon and steelhead. Red Rock Creek will also benefit from the reach downstream to SW Dartmouth Storm Sewer Assessment and Extension Rank: 16 CIP 503 Street is in this range. Essentially the only Redevelopment is a City priority in program to extend storm sewer to areas Red Rock Creek Grade Control & risk of critical damage from erosion in Tigard Triangle, where many lots without it. Culvert Improvement Red Rock Creek is where the sewer line is are small. Stormwater facilities can Rank: 16 CIP 504 located just feet from the channel. compete for space with other needs, Proposed CIPs in Red Rock Creek expand Red Rock Creek Daylighting & Riparian and requirements to treat and detain detention capacity in existing natural Restoration Water quality is also a concern in Red runoff on redevelopment sites areas and help prevent erosion that Rank: 18 CIP 502 Rock Creek as a tributary to Fanno Creek. may be perceived as a deterrent to threatens the sanitary sewer pipe by Total Cost: $13.9 million Fanno Creek is home to native fish and redevelopment in the Tigard Triangle. improving the floodplain greenway.

Red Rock Creek - page 1 - Red Rock Creek Study Area

expose the sewer line. In the last decade, Oregon Department of Transportation the sewer line has broken six times. has tentative plans to widen both Hwy 217 and I-5 in the area. The City has identified the Tigard Triangle as a center for economic development These improvements will include and transit-oriented redevelopment. rehabilitation and expansion of existing Metro’s Southwest Corridor Plan stormwater facilities in the Red Rock links fish-passage and natural area Creek study area. improvements to the proposed MAX light rail line from downtown Portland, through the Tigard Triangle, and to Bridgeport Village.

Red Rock Creek - page 2 - Study Area Summary August 2017 Ash Creek Study Area

Existing Conditions Ash Creek flows southwest into the water quality requirements and stream and encroached into the historically wide northeast corner of Tigard. The Ash Creek and wetland setbacks were in effect. floodplain. study area is 1.4 sq. mi. Washington Square Mall and adjacent Many culverts in the basin were designed Ash Creek and its tributaries drain an developments comprise more than 200 to handle stream flows based on historic urbanized area of southwest Portland. In acres of impervious area with no water conditions, and they are overwhelmed by Tigard, the creek flows under Hwy 217, quality treatment. the increased runoff from urbanization. past Washington Square Mall, and under railroad tracks to meet Fanno Creek near In the hilly upper basin, homes and yards Where the creek is constricted by SW North Dakota Street. were sometimes built over the creek. culverts, bridges, or beaver dams, In the flatter lower basin, commercial local flooding often occurs. Without a The basin was developed before most development has straightened the creek continued on back page Issues and Risks Proposed CapitalStrategies Improvement and Solutions Projects The Stormwater Master Plan assessed the Clean Water Act for phosphorus, The primary strategies in Ash Creek likely near Hwy 217. The Washington the risk of erosion in Tigard’s streams. bacteria, dissolved oxygen, and are stream resilience and shading. The Square Mall Retrofit Plan program will The assessment analyzed the likelihood temperature. highest priority capital improvement focus on studying and identifying the of erosion based on stream geology and projects are located in the lower basin most effective locations for mitigating the the consequence of erosion based on the Pollutants commonly associated with within a mile of Fanno Creek. effects of runoff from acre upon acre of stream’s proximity to important features urban runoff from commercial areas impervious surface. such as roads, sewer lines, and buildings. include metals, hydrocarbons, and Reconnecting the floodplain in two particles, which can cause cloudy water. locations should reduce local flooding Proposed CIPs The headwaters of Ash Creek pass and fortify the creek to handle the Bagan Park Stream Restoration and through homeowner association open unmanaged runoff from upstream Beneficial uses of spawning and rearing Water Quality Enhancement space and Senn Park in a steep canyon for threatened steelhead, which require development, including in Portland. Rank: 9 CIP 101 which also carries a 12-in diameter cold water, are protected under the Clean These two projects also will allow for sanitary sewer pipe. This reach is Water Act through a Total Maximum riparian restoration to increase stream Oak Street Property Acquisition and classified as a severe overall erosion Daily Load for temperature. shading to decrease temperatures. Detention risk. Most of the remaining portion of Rank: 14 CIP 106 the main stem in Tigard has moderate Ash Creek lacks shade where riparian Shade could also be increased through Total Cost: $1.3 million to moderately severe overall risk. A canopy cover has been reduced or partnerships to restore vegetated buffers tributary that flows parallel to SW Spruce removed by development. Shade from and dedicate them to the City when Street is classified as moderately low risk. canopy cover effectively cools streams. properties along Ash Creek redevelop.

Ash Creek is water quality limited under Improvements in water quality are most

Ash Creek - page 1 - Ash Creek Study Area

functioning floodplain, floods impact a large wetland. From this point to the trout are listed as threatened under the roads and businesses during bigger with Fanno Creek, most Endangered Species Act. storms. of Ash Creek and its adjacent riparian corridor are classified as Highest Value Beaver are active throughout Ash Creek. Throughout the study area, channels are Habitat in the Tualatin Basin Fish & eroding downward and creating nearly Wildlife Habitat Program to meet the vertical banks, a process called incision. State of Oregon’s Planning Goal 5 to Incision decreases the ability of a stream protect natural resources and conserve to overtop into its floodplain and sends open spaces. more water downstream. This process exacerbates any downstream flooding. Steelhead trout are known by Oregon Department of Fish & Wildlife to use Ash East of Hwy 217, Ash Creek flows into Creek. In the Tualatin Basin, steelhead Ash Creek - page 2 - Study Area Summary August 2017 Bull Mountain Study Area

Existing Conditions Several large tributaries to Summer Creek across. Very little stormwater detention property where Kruger Creek is nearly and Fanno Creek begin on the slopes of has been provided here, so increased undermining a house. Bull Mountain in southwest Tigard. The runoff from urbanization flows very Bull Mountain study area is 3.1 sq. mi. quickly to these geologically unstable Sewer lines are also at risk in the canyons headwater streams. and valleys of Bull Mountain creeks. Creeks flow quickly down steep and narrow wooded canyons. Headwaters of Through an effect of erosion called In the lower reaches of the tributaries, these streams may drop 300 feet in half incision, some streams have developed historic development occurred before a mile. vertical streambanks up to 35 feet deep. requirements for stream setbacks were Incised streams can undermine adjacent in effect. Homes are located very close Residential developments are perched structures, as is the case at SW Gallin to the creek. Eroded soils from steep and above the canyons, at times only 300 feet Court, where the City purchased a private continued on back page Issues and Risks Proposed CapitalStrategies Improvement and Solutions Projects The Stormwater Master Plan assessed is high. Where greenways are narrow, Proposed CIPs Proposed CIPs the risk of erosion in Tigard’s streams. allowing homes and utility lines to Gallin Court Stream & Culvert Hunter’s Glen Pond Rehabilitation The assessment analyzed the likelihood approach close to these steep streams, Improvements of erosion based on stream geology and overall risk is assessed as moderately Rank: 11 CIP 303 the consequence of erosion based on the high to high. Rank: 1 CIP 304 Total Cost: $12.9 million stream’s proximity to important features Derry Dell West Stream Protection such as roads, sewer lines, and buildings. Lower reaches are somewhat more likely Rank: 2 CIP 305 The strategy for the degraded Bull to have a low overall risk of erosion. In Derry Dell East Stream & Culvert Mountain streams is to prevent sewer Throughout the Bull Mountain study these reaches, maintenance of water Improvements lines and buildings from exposure and area, erosion is the predominant quality by reducing upstream erosion is Rank: 2 CIP 306 collapse and to reduce sedimentation concern. the highest concern. in downstream reaches. Kruger Creek is Kruger Creek Ann Court Bank where the most severe problems have Stabilization & Wetland Enhancement In almost all cases, the headwater None of the Bull Mountain streams already occurred. streams on Bull Mountain are highly have threatened or endangered fish; Rank: 6 CIP 302 susceptible to erosion due to geology of however the non-profit organization Kruger Creek Knickpoint Stabilization & The strategy for less-degraded streams, the area. Overall risk is highest where Trout Unlimited has worked on fish Stream Restoration such as Derry Dell Creek, is to preserve bank failures could undermine sanitary passage improvements and fish habitat Rank: 7 CIP 308 and enhance channels and riparian sewer lines, homes, or roads. Where improvements on Derry Dell Creek. Gaarde Street Greenway Detention & corridors. These streams can then be streams flow through sufficiently wide Sewer Line Protection used as references to gauge success of greenways, overall risk has been assessed Rank: 10 CIP 310 investments in degraded streams. Clean as low, even if the likelihood of erosion Water Services is a key partner.

Bull Mountain - page 1 - Bull Mountain Study Area

incised upper reaches travel downstream In an effort to protect sanitary sewer and block inlets and culverts. lines, Clean Water Services has been focusing on riparian restoration projects Because development on Bull Mountain in Derry Dell Creek for more than ten began in the east and moved west, the years. Although the riparian vegetation eastern tributaries have been more on the creek is in good condition in these greatly impacted by development and areas, the stream channel continues to are more degraded than the western erode. tributaries. Kruger Creek is the most impacted. Later developments preserved more riparian buffers, such as in Derry Dell Creek, reducing impacts on streams. Bull Mountain - page 2 - Study Area Summary August 2017 Summer Creek Study Area

Existing Conditions Summer Creek enters Tigard under Most of the Bull Mountain study area floodplain in a number of areas. In a few Barrows Road from Beaverton and meets creeks are tributaries to Summer Creek. neighborhoods that were developed Fanno Creek near Thomas R. Fowler Unlike the fast-moving streams tumbling prior to stream setbacks regulations, Middle School. The study area is only down Bull Mountain, Summer Creek is homes are located in the floodplain. 0.75 sq. mi., but the creek drains a large nearly flat and meanders through its urban basin upstream of Tigard. greenways. Summer Creek falls only 50 Several sanitary sewer lines cross feet in two miles. perpendicular to creek flows. Although In Summerlake Park an historic dam Clean Water Services has been pursuing across the creek creates a lake. The Much of Summer Creek’s floodplain options to abandon these crossings, the open expanse of slow-moving water has in Tigard is wide with good riparian pipes remain a spill risk in the meantime. produced significant water temperature vegetation. However, historic incision increases during summer. has disconnected the creek from its continued on back page Issues and Risks Proposed CapitalStrategies Improvement and Solutions Projects The Stormwater Master Plan assessed is classified as moderate to moderately The primary strategies proposed for the reducing transport of sediment from the risk of erosion in Tigard’s streams. high. Summer Creek study area are water Kruger Creek into Summer Creek. The assessment analyzed the likelihood quality enhancement and temperature of erosion based on stream geology and Only one small stretch of Summer Creek reduction. A multi-pronged effort is One priority CIP in the study area is the consequence of erosion based on the is classified with high overall erosion risk. proposed in the Summer Lake Water downstream of Summerlake Park and will stream’s proximity to important features Quality Enhancement Program. The remove a structure from the floodplain. such as roads, sewer lines, and buildings. Bacteria is a concern in Summer Creek. program includes shading and habitat The beneficial use of primary contact enhancements on islands and selected Proposed CIPs The first mile of the Summer Creek study recreation is protected under the shorelines in Summerlake Park, floating SW 116th Avenue Property Acquisition area in Tigard is classed in the lowest Clean Water Act (CWA) through a Total treatment islands, rain gardens in & Floodplain Storage overall risk category for erosion. Wide Maximum Daily Load (TMDL) for bacteria. adjacent neighborhoods, continued greenways and parks flanking the creek outreach on bacteria reduction, and Rank: 4 CIP 702 have kept development away from the The beneficial use of salmonid fish other actions. Total Cost: $1.2 million channel through these reaches, and flat rearing, which requires cold water, is grades reduce the likelihood of erosion. also protected under the CWA through In addition, upstream tributaries to a TMDL for temperature. Summer Summer Creek in the Bull Mountain The second mile is characterized by stream temperatures at Fowler Middle study area have been prioritized in the somewhat narrower greenways, more School have reached higher than 70° F, Stormwater Master Plan. Three capital frequent sewer crossings, and some a temperature which can stress or harm improvement projects (CIPs) proposed areas of development in the floodplain. native salmon and steelhead. on Kruger Creek could positively impact Overall risk of erosion in these reaches water quality in Summer Creek by

Summer Creek - page 1 - Summer Creek Study Area Through most of its length in Tigard, Summer Creek flows through established greenways and City parks. With public land flanking much of Summer Creek, riparian restoration efforts have been ongoing for nearly ten years. Clean Water Services recently took over restoration and maintenance activities.

Much of the Summer Creek study area is in relatively good condition. Many of the water quality concerns in the study area can be attributed to Summer Lake.

High bacteria levels have been measured downstream of Summerlake Park. Bacterial levels fell after a successful effort to reduce sources of bacteria. Between 2005 and 2007, the city installed vegetative filter strips at the dog park, worked with a private property owner to dismantle a waterfowl feeding station, and began removing nutria from the lake. A dog waste pick- up outreach campaign ran in 2007.

Despite these improvements, Summer Lake continues to have high bacteria and high temperatures.

Summer Creek benefits from strong community interest and various ongoing education and stewardship opportunities offered by Tualatin Riverkeepers, Clean Water Services, and the Tigard Tualatin School District.

Summer Creek - page 2 - Study Area Summary August 2017 Tualatin River Tributaries Study Area

Existing Conditions Two main stream systems in southern Another tiny tributary to the Tualatin less setbacks and water quality regulations Tigard drain the Summerfield than 1/10th of a mile in length originates took effect. neighborhood and the neighborhoods in Cook Park. south of SW Durham Road directly to the Headwater streams in the Summerfield Tualatin River. The Tualatin River Tributaries study area community and golf course have been is just under 1.5 sq. mi. piped as they head south toward SW Copper Creek, which is often known Durham Road. as Spring Creek on maps, follows SW In the northern heights of the study area, Copper Creek Drive into Cook Park. An surface water and stormwater runoff are Open stream channels flow south from un-named system further west generally directed to piped storm sewers. These approximately SW Durham Road. Fast, follows the Tigard City limits and meets neighborhoods were developed in the constrained flows through culverts under the Tualatin River at Dover Landing. 1960’s through 1980’s before stream continued on back page Issues and Risks Proposed CapitalStrategies Improvement and Solutions Projects The Stormwater Master Plan assessed Urban runoff from the types of land uses Strategies in the tributaries to the Plan led to the development of several the risk of erosion in Tigard’s streams. in this study area tends to contain: Tualatin River include dissipating energy potential projects in this study area. The assessment analyzed the likelihood downstream of eroding culverts and None of the potential projects ranked of erosion based on stream geology and • Excess nutrients from lawn care and using retaining walls, bioengineering, highly enough to appear in the Capital the consequence of erosion based on the golf course maintenance practices; and grade controls to stabilize unstable Improvement Program. The City will stream’s proximity to important features • Metals from high-use roads such as banks. continue to monitor problem spots and such as roads, sewer lines, and buildings. SW Durham Road; plans to re-evaluate CIP ranking on a The City’s recent investments in solutions regular basis. Approximately 90% of Copper Creek is • Bacteria from animal waste, including for erosion in several locations just below classified as moderately high to high pet dogs, water fowl, and beaver; and SW Durham Road have stabilized some of The Tualatin Tributaries study area may overall risk of erosion. Approximately • Particles and sediment from roads the worst problems that were occurring benefit from roof drain extensions. They 50% of the western-most tributary and landscaping as well as from in these tributaries. could reduce erosion of private property system is classified moderately high to erosion in the channels themselves. into creek channels by extending high, while about 25% is moderate. Lack of trees to shade streams in Creeks in this area flow mostly through residential rain drains that discharge developed areas without adequate privately-owned property. There are at the top of steep stream banks. Roof As tributaries to the Tualatin River, water stream setbacks can increase summer few opportunities to provide solutions drains are extended down the stream quality is a concern in these streams. stream temperatures. on public property, where long-term banks to the ordinary high water mark. The Tualatin River is water quality maintenance can be better assured, and Roof drain extensions may be offered limited under the Clean Water Act for where the general public benefits more. as a part of the Technical Assistance phosphorus, bacteria, dissolved oxygen, Program. and temperature. Analysis for the Stormwater Master

Tualatin River Tributaries - page 1 - Tualatin Tributaries Study Area

Durham are eroding the downstream channels in both tributary systems.

Bank instability caused by erosion has threatened buildings and trees on private properties just south of Durham. In recent years, the City has invested in several solutions to address this erosion.

Further evidence of damage from erosive flows are deep headcuts where the tributaries meet the Tualatin River.

Tualatin River Tributaries - page 2 - Study Area Summary August 2017 River Terrace Study Area

Existing Conditions River Terrace is a 0.8 sq. mi. study area at Washington County to the Tualatin River. 30 years. The Stormwater Master Plan the far western edge of Tigard. used hydraulic and hydrologic modeling As in the Bull Mountain study area, to study the capacity of the storm sewer River Terrace was annexed to the City creeks in and below River Terrace fall system to handle current flows and flows recently and is currently undergoing quickly down the mountain in highly expected from future development. rapid development to primarily erodible channels composed of fine soils. residential land use from rural land use. Because of the recent intensive planning The City completed the River Terrace in River Terrace, the study area was not The study area is perched on the western Community Plan in 2014 and the River included in the city-wide Stormwater slopes of Bull Mountain. Eight small Terrace Stormwater Master Plan in 2015 Master Plan’s evaluation of erosion risk. stream systems flow west and south from to guide development and stormwater River Terrace through unincorporated management in the area over the next continued on back page Issues and Risks Proposed Strategies and Solutions Proposed Capital Improvement Projects Under current rural conditions, River To protect tributary streams and the and to slowly release stored runoff Terrace tributaries to the Tualatin River Tualatin River, new housing and mixed- after storms. Facilities must serve as would likely continue to degrade. Further use developments in River Terrace are community amenities. degradation could include channel required to meet stringent new standards incision (the process of eroding the for stormwater control. Standards in Area B channel bottom, creating vertical or near place in River Terrace exceed those in use Area B consists of two relatively small vertical banks) and channel widening. in Tigard and throughout the rest of the non-contiguous areas where small-scale Clean Water Services district. Low Impact Development Approaches Managing stormwater impacts of River (LIDA), such as rain gardens, will provide Terrace’s rapid transformation from rural Three areas have been designated for water quality treatment while regional to urban and suburban is essential to different types of stormwater strategies. detention ponds will slowly release preventing further damage to streams. The map at right shows the location of stored runoff after storms. Like the each strategy area. combined regional facilities in Area A, Creeks in River Terrace are tributaries regional detention facilities must serve as to the Tualatin River. Water quality is Area A community amenities. a concern. The Tualatin River is water Roughly half of River Terrace will use quality limited under the Clean Water regional combined water quality and Area C Act for phosphorus, bacteria, dissolved water quantity control facilities. Each For Area C, in the southwest corner of oxygen, and temperature. These water large facility will serve a substantial area the study area, the 2015 River Terrace quality concerns affect threatened fish, of new development. Facilities will be Stormwater Master Plan recommended other wildlife habitat, and human health. designed both to remove pollutants continued on back page

River Terrace - page 1 - River Terrace Study Area Existing Conditions, continued Proposed Strategies and Solutions, continued The River Terrace Stormwater Master Plan found use of LIDA to remove pollutants and conveying the following existing conditions: high flows from storms around erodible and vulnerable tributaries to the Tualatin River. • Culverts under Roy Rogers Road have capacity However, the cost to build the conveyances for current flows exceed the City’s capacity to fund it. As a result, the City allows LIDA for treatment and regional • Culverts under Beef Bend Road are water quantity facilities to detain runoff, similar to undersized for current flows Area B. • Existing culverts under Roy Rogers and Beef Bend roads may block fish passage The strategy for Area C may be re-evaluated if the • Steep drainages in soils with fine sediments urban growth boundary expands to the south of below River Terrace are at a high risk for River Terrace. erosion Modeled Stormwater Facilities • Clayey soils overlay basalt bedrock on hilly The map at left shows locations of regional terrain, limiting the use of infiltration to facilities modeled in Areas A and B. Actual manage stormwater regional facilities proposed by developers during • Most tributaries are in an advanced stage of the land use and engineering review process are channel degradation not required to be located in the exact locations of the modeled facilities shown on the map. Stormwater facilities were not modeled for Area C.

River Terrace - page 2 - Study Area Summary August 2017 Ball Creek Study Area

Existing Conditions At 0.4 sq. mi., Ball Creek is the smallest overlaps the City’s Tigard Triangle urban upstream of the Portland & Western area studied for the Stormwater Master redevelopment area. Railroad tracks in the study area have Plan. been straightened to accommodate The creek has been greatly altered development. Ball Creek runs through a heavily by piping and straightening. A large industrial and commercial area west of diameter culvert conveys Ball Creek Only very narrow riparian corridors the I-5 and Hwy 217 interchange. The underground nearly 1,200 feet under remain. Incision, which is the formation Ball Creek system flows into Tigard from three different industrial properties of deep, steep banks resulting from Portland and Lake Oswego. The creek immediately west of I-5 as well as under downward erosion of the steam channel, flows for a total of 0.7 miles in Tigard. SW Bonita Road to SW 72nd Avenue. is occurring along most of the creek.

A small portion of the study area All remaining open channel segments continued on back page Issues and Risks Proposed Capital Improvement ProjectsProposed Solutions The Stormwater Master Plan assessed not own or control most of it, except a along with pollutants common to all One strategy in Ball Creek is to maintain, the risk of erosion in Tigard’s streams. small portion in the street right-of-way urban runoff such as sediment. repair, and rehabilitate existing storm The assessment analyzed the likelihood (ROW). Its location under buildings and sewers and culverts to maintain of erosion based on stream geology and parking lots creates logistical challenges A Metro property at the mouth and City conveyance capacity in the system. the consequence of erosion based on the for repair, rehabilitation, or replacement. and ROW are the only public lands along stream’s proximity to important features In addition, it passes under properties Ball Creek. Lack of usable space limits The northern part of the study area such as roads, sewer lines, and buildings. controlled by three separate owners. the City’s ability to build above ground may benefit from the Tigard Triangle detention and water quality facilities to Stormwater Implementation Plan. The Nearly all of Ball Creek is classified as a Water quality is a concern. Ball Creek control flows and improve water quality plan will support redevelopment, which moderate overall erosion risk. drains to Fanno Creek, which is water in the area. Underground solutions or will bring properties up to current water quality limited for bacteria, dissolved partnerships with private landowners quality treatment standards. The large underground culvert that oxygen, phosphorus, and temperature may be possible. conveys Ball Creek under several under the Clean Water Act. Oregon A partnership with ODOT to treat and commercial properties is perhaps the Department of Environmental Quality Flooding is another concern. The detain runoff from I-5 and Hwy 217 is biggest risk in the study area. A collapse recently added arsenic, iron, lead, intersection of SW 72nd Avenue and SW possible. Tigard will support Clean Water or significant blockage of the pipe could tetrachloroethylene, and zinc to Fanno Bonita Road flooded during a December Services’ programs to restore vegetated result in flooding upstream, property Creek’s water quality limitations. 2015 rain storm after the large culvert’s corridors on private properties and will damage, and danger to people. trash grate was blocked by debris. partner with CWS and Metro at Ball Industrial and commercial land uses Creek’s confluence with Fanno Creek. The culvert is vital to conveying the have been found to discharge metals, creek through the basin, yet Tigard does hydrocarbons, nutrients, and chemicals, There are no priority CIPs in Ball Creek.

Ball Creek - page 1 - FannoBall Creek Creek Study Study Area Area DRAFT

Downstream of SW 74th Avenue, Ball Creek meets Fanno Creek in a mapped significant wetland at an open space owned by Metro. Most of Metro’s open space along Ball Creek falls within the Fanno Creek study area boundary and is not further discussed in the Ball Creek study area fact sheet.

The Ball Creek study area was developed before most water quality regulations were in effect. Despite draining I-5, Hwy 217, and more than 200 acres of industrial and commercial impervious area, there is almost no water quality treatment in the study area.

Ball Creek - page 2 -