CHAPTER| - Department of Public Works, Los Angeles …dpw.lacounty.gov/wmd/watershed/bc/bcmp/docs/sept04...Centinela Avenue to approximately Venice Boulevard, and then zigzags southwest

Ballona Creek Watershed Management Plan

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Ballona Creek Watershed Task Force

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CHAPTER|TWO

Ballona Creek


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CHAPTER TWO

existing conditions

1 Clastic refers to a rock or sediment composed primarily of broken fragmentsderived from preexisting rocks or minerals that have been transported somedistance from their place of origin.

A. WATERSHED BOUNDARY

The Ballona Creek Watershed, located in the westernportion of the Los Angeles Basin, is a drainage area ofapproximately 130 square miles. The general boundariesof the watershed (Figure 2-1) include MulhollandHighway in the Santa Monica Mountains and theridgeline in the Hollywood Hills on the north, thewestern portion of Silverlake (west of the reservoir) andEcho Park (west of Echo Park Lake), and the I-110 freeway(and the southwestern portion of downtown Los Angeles)on the east, and Manchester Boulevard and theWestchester Bluffs on the south. The western boundarybegins just west of Sepulveda Boulevard in the SantaMonica Mountains, and generally follows Bundy/Centinela Avenue to approximately Venice Boulevard,and then zigzags southwest towards Marina del Rey andthe Ballona Creek Channel. The watershed planning areaincludes the coastal interface zone and coastal waters ofMarina del Rey, the Venice Canals, Ballona Lagoon, DelRey Lagoon, and Oxford Lagoon (also known as theOxford Flood Control Basin) as water quality in theseareas are interrelated.

B. GEOLOGY AND FAULTING

The Ballona Creek Watershed is located on the coastalplain of the Los Angeles basin, with the Santa MonicaMountains on the north and the Baldwin Hills on thesouth. The Santa Monica Mountains form the centralportion of the Transverse Ranges of Southern California,running from Point Arguello (north of Santa Barbara)into the Mojave Desert. The Transverse Ranges consistof several large areas of seismically active upliftedbasement rocks. The Baldwin Hills represent a surfaceexpression of the Newport/Inglewood Fault, formed overthe past several million years. West of the Baldwin Hills,the Ballona Escarpment, created over time by erosionalactivity of Ballona Creek, generally forms the southernedge of the Watershed. The topography of the Watershedis shown in Figure 2-2.

The Watershed is generally located on what is known asthe Southwestern Block of the Los Angeles basin (theportion of the basin south of the Santa MonicaMountains), which consists chiefly of marine clastic1 andorganic sedimentary strata of middle Miocene to recentepoch (from 14.5 to 1.7 million years ago), includingigneous rocks of middle Miocene epoch. The lowersequence generally consists of marine sandstone, siltstone,and minor amounts of conglomerate, deposited in ashallow marine environment.


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Figure 2-1 Ballona Creek WatershedSOURCE: LA County, Department of Public Works, Watershed Boundaries, Channels, and Roads, May 2003; EIP Associates, GIS, June 9, 2003


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Figure 2-2 Ballona Creek Watershed TopographySOURCE: LA County, Department of Public Works, Watershed Boundaries, Channels, Roads, and Topography May 2003;

EIP Associates, GIS, March 17, 2004


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2 Maximum credible earthquake is the largest earthquake (measured inmagnitude on the Richter Scale) that appears to be reasonably capable ofoccurring under the presently known geologic framework.

At the base of the Santa Monica Mountains (and theBaldwin Hills), these deposits are overlain by gentlyrolling terrain consisting of alluvial deposits, depositedas alluvial fan material resulting from erosion of thesouthern slopes of the Santa Monica Mountains and theslopes of the Baldwin Hills, respectively. In some locationssouth of the Santa Monica Mountains, these alluvialsurface deposits were incised by stream channels, whichgenerally faded across the broad coastal plain. Along thecoast, the marine deposits are generally covered bywindborne sand (deposited during the Pleistocene) oralluvial materials deposited by Ballona Creek.

The Ballona Creek Watershed includes two major faultsystems, the Santa Monica Fault zone and the NewportInglewood fault zone, and numerous smaller faults. TheSanta Monica Fault zone is comprised of several majoractive faults, including the Malibu Coast and SantaMonica–Hollywood Faults, which runs along thesouthern edge of the Santa Monica Mountains. The activeNewport-Inglewood Fault runs from off the coast ofNewport Beach to Culver City, and is responsible forthe chain of low hills extending from Signal Hill to theBaldwin Hills. Each of these fault zone systems is capableof producing large earthquakes, with a maximum credibleearthquake2 estimated as a magnitude 7.5 event on theSanta Monica–Hollywood Fault and a 7.4 event on theNewport-Inglewood Fault. Both of these would resultin severe earthshaking in most of the Watershed. Majorfaults in the vicinity of the Watershed are depicted onFigure 2-3.

Portions of the watershed are underlain by oil deposits,created by organic matter deposited long ago andsubsequently covered by layers of rock and othersediments. Although Native Americans, and laterSpanish settlers, utilized tar from La Brea Tar Pits towaterproof baskets and other materials, it was not until1892 that extraction of oil began in the watershed, withthe discovery of oil in Echo Park. In the coming decades,oil wells were drilled throughout portions of thewatershed. Initially, production was generally limitedto downtown Los Angeles and the area to the west, butexploration continued to move west. With the discoveryof the Inglewood oil field in 1924, production began inand around the Baldwin Hills. Oil was discovered inthe Venice area in 1930, which initiated an oil boomalong the coast. Today, oil extraction continues in theBaldwin Hills, with more limited production at scatteredlocations throughout the Watershed.


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Figure 2-3 Major Faults in the Watershed VicinitySOURCE: CDMG OFR 92-03 (1992), USGS MFI-512 (1965)


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SFIGURE 2-4 SEASONAL VARIATION IN HIGH AND LOW TEMPERATURES, CULVER CITY

Figure 2-5 Seasonal Distribution of Rainfall

Figure 2-4 Seasonal Variation in High and Low Temperatures, Culver CitySOURCE: Western Regional Climate Center

SOURCE: Common Ground, from the Mountains to the Sea, per datafrom the Western Regional Climate Center

C. CLIMATE

The Ballona Creek Watershed is within theMediterranean climate zone of California, which extendsfrom Central California to San Diego and is characterizedby wet winters and long dry summers. Other thanCalifornia, this climate type only occurs in coastal zonesalong the Mediterranean Sea, Western and SouthernAustralia, the Chilean coast, and the Cape Town regionof South Africa.

The topography of the Los Angeles region results in agreat deal of spatial variation in the local climate. Theproximity and steep rise of the San Gabriel Mountainsfrom the coast creates a barrier that traps moist ocean airagainst the mountain slopes and partially blocks summerheat from the desert and winter cold from the interiornortheast. Average daytime summer and wintertemperatures range from 71/63F° at the coast to 83/66F° downtown. Figure 2-4 shows the variation in annualmonthly temperatures in Culver City.

Long-term annual rainfall averages vary from 12.5 inchesalong the coast to 15.5 inches in downtown Los Angeles,with most precipitation falling in a few major stormevents between November and March. The seasonal

distribution of rainfall is provided in Figure 2-5. Forany given storm event, rainfall totals vary across theWatershed. The maximum recorded 24-hour rainfall inthe Watershed ranges from 4.5 inches in Culver City to5.88 inches at downtown Los Angeles.

Most winter storms come from the northwest, movingacross Southern California into Arizona. Typical stormsin the Watershed bring ¾ inch or less of rainfall. Stormsfrom the south or southwest are less common, butbecause they may stall off the coast, they may bring 3 to6 inches of rain over portions of the Watershed. Summerrains are rare, but when they occur they are a result oftropical thunderstorms originating in the Gulf of Mexicoor late summer hurricanes off the West Coast of Mexico.


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Figure 2-6 Historic Ballona Creek Watershed Drainage Area Overlay Map, 1896 and 1986SOURCE: Braa et al. 2001, Seeking Streams: A Landscape Framework for Urban and Ecological Revitalization in the Upper Ballona Creek Watershed

D. HYDROLOGY

Historically, Ballona Creek was a meandering stream,lined with dense vegetation that met the Pacific Oceanin a broad expanse of tidal lagoons and wetlands. Variousperennial and intermittent streams were located in thecanyons of the Santa Monica Mountains; however,according to historical maps, many of these tributariesdisappeared as they crossed the coastal plain (presumablydue to percolation of instream flow to groundwater).High groundwater in West Hollywood and the areaknown as La Cienega (e.g., including present dayHancock Park) resulted in surface seeps and springs,which resulted in the formation of marshland andswamps. At times, runoff from these areas may have been

sufficient to feed a perennial tributary to Ballona Creek.Another area of marshland and swamps was locatednortheast of the Baldwin Hills, possibly due to theNewport-Inglewood Fault serving as a barrier togroundwater movement. Various intermittent streamswere also found in the area around the Baldwin Hills,along with Centinela Creek, which drained the southernportion of the Watershed. In some areas, winter rainstransformed surface depressions and areas with denseclay soils into seasonal vernal pools. Because tidal flushingwas not constrained, the estuary of Ballona Creek andthe associated tidal wetlands trapped sediment erodedfrom upland areas and collected runoff behind barrierbeaches. Figure 2-6 overlays the historic stream patternsover current development, depicting the general locationof these streams.


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Until the twentieth century, Ballona Creek and thevarious tributaries were largely unconstrained. Whenwinter rains swelled the creeks, they often changedcourse, flooding farms, homes and businesses. As urbandevelopment moved west of downtown Los Angeles,various tributaries began to be channelized or filled in.The increasing urban and suburban development alsoincreased the extent of impervious surfaces, increasingrunoff volumes from storm events. A flood in 1914resulted in considerable property damage and left areasnear the coast flooded for many months.

Channel confluence

The City of Los Angeles began to straighten portions ofBallona Creek in the 1920s. Following a subsequentflood in 1934, the U.S. Army Corps of Engineers(USACE), in conjunction with the Los Angeles CountyFlood Control District (LACFCD), lined the lowerportions of the creek channel with large rocks (quarriedfrom Santa Catalina Island) and channelized the upperportions in concrete between 1935 and 1939. The majortributaries to the Creek were channelized starting in

1950, with the Sawtelle-Westwood system built betweenMarch 1950 and February 1960, Centinela Creekchannel between 1960 and 1962, and the BenedictCanyon system channels (including Higgins andColdwater Canyon Channels), between December 1962and January 1964. Between 1959 and 1965, in responseto the 1941 Flood Control Act, the USACE and theLACFCD modified the existing Ballona Creek channelby dredging silt deposits, raising walls and levees, andgrouting the levee facing. Currently, Ballona Creek isdesigned to discharge approximately 71,400 cubic feetper second into Santa Monica Bay from a 50-yearfrequency storm event. Two sections of Ballona Creekare still maintained by USACE, seaward of Pacific Avenue(near the mouth) and between La Cienega Boulevardand La Salle Avenue (upstream). The Los Angeles CountyDepartment of Public Works (LACDPW) maintainsother portions of the Creek.

Today, most of the drainage network in the Ballona CreekWatershed is controlled by structural flood controlmeasures, including debris basis, storm drains,underground culverts, and open concrete channels.Ballona Creek remains underground in the easternportion of the Watershed, becoming an open channelnear Venice Boulevard and Pickford Street (about sixblocks west of La Brea Avenue), before continuingapproximately nine miles to Santa Monica Bay. Only afew channels remain open for major portions of theirlength, including the Sepulveda Wash (also known asWalnut Creek) and Centinela Creek. Very few naturalstream channels remain, mostly in the Santa MonicaMountains and Baldwin Hills. Some former streams inthe major canyons have been channelized and remainopen channels at some locations, including Stone CanyonCreek and Benedict Canyon Creek. A few remnantchannels also exist on the coastal plain, in some parks(such as Pan Pacific Park in the Fairfax area), on the UCLAcampus, and on private land, including some backyardsalong former drainage courses, and at least two golfcourses, including the Wilshire Country Club and LosAngeles Country Club.


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3 An anticline is a surface rise where the underlying rocks dip on either sideof the rise.

1-2ELBATwolFffonuRemertxEkeerCanollaB

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ecruoS ,sreenignEfosproCymrA.S.U: anollaBdnayeRledaniraMydutSytilibisaeFkeerC 3002,

Due to the extensive modification of the creek andtributaries, natural hydrologic functions have beensignificantly reduced in the Watershed. Withapproximately 40 percent of the Watershed covered withimpervious surfaces (Stolzenbach 2001), runoff entersthe creek and tributaries more quickly, and in greatervolume than occurred prior to development. Extremerunoff flow conditions for the Creek (at SawtelleBoulevard), is provided in Table 2-1. Infiltration ofprecipitation to groundwater has been reduced andriparian vegetation and aquatic habitat has beeneliminated from most channels. As most channels arenow lined with concrete, the natural processes of erosionand sedimentation have been altered, with erodedsediment now transmitted to the mouth of Ballona Creek(where it periodically results in partial closure of theboat entrance to Marina del Rey). The construction oflevees on Ballona Creek, coupled with construction ofMarina del Rey significantly reduced the extent of tidalwetlands, and reduced the extent of tidal flushing in theestuary and associated lagoons (including Del ReyLagoon and Ballona Lagoon). With the introduction ofimported water and extensive landscaping, runoff fromlandscape irrigation has created year-round flows in mostchannels, which historically were dry most of the year.

E. GROUNDWATER

Groundwater is located under most of the Ballona CreekWatershed, which is primarily underlain by agroundwater formation known as the West Basin(comprised of the Hollywood and Santa Monicasubbasins) and a small portion of the Central Basin underthe southeastern portion of the Watershed. TheHollywood subbasin is bounded on the north by SantaMonica Mountains and the Hollywood Fault, on theeast by the Elysian Hills, on the west by the InglewoodFault zone, and on the south by a surface divide knownas the “La Brea high,” formed by an anticline3 that bringsimpermeable rocks close to the surface. The Santa Monicasubbasin is bounded by the Santa Monica Mountainson the north, the Ballona escarpment on the south, theInglewood Fault zone on the east, and the Pacific Oceanon the west. The Central Basin is bounded on the northby the La Brea high, and on the northeast and east byless-permeable rocks of the Elysian, Repetto, Merced,and Puente Hills. The southeast boundary of the CentralBasin roughly follows Coyote Creek, while the southwestboundary is formed by the Newport-Inglewood Faultsystem.

Groundwater in the Ballona Creek Watershed isreplenished by percolation of rainfall and stream flowfrom the Santa Monica Mountains to the north and theBaldwin Hills to the south. With approximately40 percent of the watershed covered by impervioussurfaces and concrete lining most tributary channels,the land area open to direct infiltration of rainfall andpercolation from stream channels has been substantiallyreduced.


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Where groundwater levels are high, permeable rocks orconfining structures, such as faults, may result ingroundwater reaching the surface as areas of moist soil, aseep, or a spring. Historically, high groundwater levelsin some portions of the Watershed resulted in marshesand surface springs. In general, most of these surfacesprings have ceased or been capped (such as the formerCentinela Springs in Inglewood). However, naturalsprings still exist at various locations in the Santa MonicaMountains and at a few locations on the coastal plain,including the Kuruvungna Springs on the grounds ofUniversity High School near the western boundary ofthe Watershed. High groundwater levels still exist inmany of the same locations where they were historicallyfound, including West Hollywood, La Cienega, Venice,and portions of Culver City. In these areas, the highgroundwater table may pose issues for buildingfoundations, result in seepage into below-grade spaces,and increase the risk of liquefaction during seismic events.

Drain clogged with debris

F. WATER QUALITY

REGULATORY BACKGROUND

The quality of water in Ballona Creek reflects the extentof human modification of the Watershed. As settlementof the area began, issues associated with humanoccupation, including animal waste and the disposal ofsewage, also became concerns. Once the creek waschannelized, as urban development became extensive,the discharge of chemical contaminants from industrialuses became an issue.

The Dickey Water Pollution Control Act of 1949established a State Water Pollution Control Board (laterrenamed the State Water Quality Control Board) andnine regional water pollution control boards that roughlycorresponded to the major watersheds in the state. In1967, the State Water Rights Board merged with theState Water Quality Control Board to create the StateWater Resources Control Board. The Porter-CologneWater Quality Control Act (of 1969) conferred broadpowers to the State and Regional boards to protect thebeneficial uses of water, and established a requirementfor water quality control plans (or Basin Plans, whichidentify beneficial uses for water bodies) for each region.The Porter-Cologne Act served as a model for the FederalWater Pollution Control Act Amendments of 1972(commonly referred to as the Clean Water Act).

In the Ballona Creek Watershed, primary authority forsurface water quality rests with the Los Angeles RegionalWater Quality Control Board (LARWQCB). The Boardhas the authority to issue permits for discharge frompoint sources and stormwater under the NationalPollutant Discharge Elimination System. The firstNPDES countywide permit for stormwater was issuedin 1990.

The 1994 Water Quality Control Plan, Los Angeles Region(Basin Plan), prepared by the LARWQCB, noted thatthe water quality in Ballona Creek was impaired bypollutants from industrial effluent, illegal dumping of


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EXIS

TIN

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ON

DIT

ION

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sewage, historical overflows of untreated sewage intoBallona Creek during the storm events, and pollutantsfrom nonpoint sources. (With recent upgrades to theHyperion Sewage Treatment Plant, overflows to BallonaCreek have been substantially curtailed.)

Per the (federal) Clean Water Act the State WaterResources Control Board adopts a list of impaired waterbodies (the “303(d)” list) for the State of California,which currently includes Ballona Creek, BallonaWetlands, and Marina del Rey (back basin). The listwas amended and updated most recently in 2002 (andadopted in February 2003) and identifies water qualityimpairments (including trash, metals, pathogens, andorganic pesticides) that restrict the beneficial usesidentified in the Basin Plan.

To preserve the beneficial uses identified in the BasinPlan, the LARWQCB has the responsibility to identifythe Total Maximum Daily Load (TMDL) for eachpollutant of concern (identified on the list of impairedwater bodies) and identify a conceptual implementationstrategy to achieve the relevant water quality standard.Although a TMDL for trash in Ballona Creek has alreadybeen established (along with a wet-weather pathogenTMDL for Santa Monica Bay and a bacteria TMDL forMother’s Beach in Marina del Rey) the majority ofTMDLs for Ballona Creek and the Watershed have yetto be established.

WATER QUALITY MONITORING

Water quality in Ballona Creek is monitored by a varietyof local agencies, including the cities of Los Angeles,Santa Monica, Culver City and West Hollywood, theCounty of Los Angeles (Department of Beaches andHarbors and Department of Public Works), the LosAngeles Regional Water Quality Control Board, theSanta Monica Bay Restoration Commission and the U.S.Army Corps of Engineers. Heal the Bay and SantaMonica Baykeeper conduct volunteer monitoring.Occasional monitoring is also performed in conjunctionwith research projects conducted by the Southern

California Coastal Water Research Project, UCLA, andLoyola Marymount University. The frequency ofmonitoring varies considerably from daily monitoringby Los Angeles City, monthly monitoring by the LosAngeles County Department of Public Works, andquarterly monitoring by Santa Monica Baykeeper. Inaddition, three snapshot sampling events were conductedduring the dry season in 2003 and additional samplingin 2004 to provide baseline data for TMDL developmentis anticipated. The County conducts water sampling attwo locations on Ballona Creek: at Fairfax Avenue andSawtelle Boulevard. The Fairfax Avenue location is usedfor dry weather flow samples only, while the SawtelleBoulevard location is used for collection of both dryweather and storm flow samples. Although Santa MonicaBaykeeper began monitoring relatively recently, theprogram samples most of the publicly accessibletributary storm drains in the lower portion of BallonaCreek. The County of Los Angeles has installed a trashnet near the mouth of Ballona Creek, to reduce theamount of trash entering Santa Monica Bay. The trashis removed periodically and the amount of trash removedis recorded, although the net is designed to catch largeritems and give way during high flow events and, thus,does not capture all of the trash in the Creek. For moreinformation on water quality monitoring, refer toChapter 5 (Community Based Monitoring Program).

SURFACE WATER QUALITY

The 303(d) list of water quality impairments in theWatershed is provided in Table 2-2 along with theregulatory standards used to identify those impairments(in Table 2-3). The amount of trash removed by theCounty of Los Angeles from the net at the mouth ofBallona Creek during 2002 is illustrated in Figure 2-7.The amount of sediment discharged by Ballona Creekhas been estimated at a total of approximately 44,615 m3

(with 39,760 m3 of sand and 4,855 m3 of silt), althoughsediment production is highly variable due to therelationship with land use, water management, andhydrological conditions within the Ballona CreekWatershed (USACE 2003).


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EXIS

TIN

G C

ON

DIT

ION

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2-2ELBATstnemgeSdetimiLytilauQretaWfotsiL)d(303noitceSAWC2002dehsretaWkeerCanollaB

emaN rossertS/tnatulloP secruoSlaitnetoPLDMT

ytiroirPeziS.tsEdetceffA

desoporPLDMT

noitelpmoC

keerCanollaB )tnemides(muimdaC ecruoStnioP/tniopnoN hgiH selim5.6 4002

)eussit(*AmehC nwonknUecruoS hgiH selim5.6 4002

)eussit(enadrolhC ecruoStnioP/tniopnoN hgiH selim5.6 4002

devlossiD,reppoC ecruoStniopnoN hgiH selim5.6 4002

)eussit(TDD ecruoStnioP/tniopnoN hgiH selim5.6 4002

)eussit(nirdleiD ecruoStnioP/tniopnoN hgiH selim5.6 4002

sesuriVciretnE ecruoStnioP/tniopnoN hgiH selim5.6 3002

tnuoCmrofiloChgiH ecruoStnioP/tniopnoN hgiH selim5.6 3002

devlossiD,daeL ecruoStniopnoN hgiH selim5.6 4002

)eussit(sBCP ecruoStnioP/tniopnoN hgiH selim5.6 4002

Hp /sreweSmrotS/ffonuRnabrUecruoStniopnoN

woL selim5.6

yticixoTtnemideS ecruoStnioP/tniopnoN hgiH selim5.6 4002

latoT,muineleS /sreweSmrotS/ffonuRnabrUecruoStniopnoN

woL selim5.6

)tnemides(revliS ecruoStniopnoN woL selim5.6

yticixoT ecruoStnioP/tniopnoN hgiH selim5.6 4002

devlossiD,cniZ /sreweSmrotS/ffonuRnabrUecruoStniopnoN

woL selim5.6

yrautsEkeerCanollaB )tnemides&eussit(enadrolhC ecruoStnioP/tniopnoN hgiH selim3.2 4002

)tnemides(TDD ecruoStnioP/tniopnoN hgiH selim3.2 4002

tnuoCmrofiloChgiH ecruoStnioP/tniopnoN hgiH selim3.2 4002

)tnemides(daeL ecruoStnioP/tniopnoN hgiH selim3.2 4002

)tnemides(sHAP ecruoStnioP/tniopnoN woL selim3.2

)tnemides&eussit(sBCP ecruoStnioP/tniopnoN hgiH selim3.2 4002

yticixoTtnemideS ecruoStnioP/tniopnoN hgiH selim3.2 4002

yrosivdAgnitsevraHhsifllehS ecruoStnioP/tniopnoN hgiH selim3.2 3002

)tnemides(cniZ ecruoStnioP/tniopnoN hgiH selim3.2 4002


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EXIS

TIN

G C

ON

DIT

ION

S

(2-2ELBAT )deunitnocstnemgeSdetimiLytilauQretaWfotsiL)d(303noitceSAWC2002dehsretaWkeerCanollaB

emaN rossertS/tnatulloP secruoSlaitnetoPLDMT

ytiroirPeziS.tsEdetceffA

desoporPLDMT

noitelpmoC

keerCanollaBsdnalteW

noitategeVcitoxE ecruoStniopnoN woL serca513

snoitaretlAtatibaH ecruoStniopnoN woL serca513

noitacifidomordyH ecruoStniopnoN woL serca513

gnihsulFladiTdecudeR ecruoStniopnoN woL serca513

hsarT ecruoStniopnoN woL serca513

yeRledaniraMsnisaBkcaB--robraH

)tnemides&eussit(enadrolhC ecruoStniopnoN muideM sercA193

)tnemides(reppoC ecruoStniopnoN woL sercA193

)eussit(TDD ecruoStniopnoN muideM sercA193

)eussit(nirdleiD ecruoStniopnoN muideM sercA193

yrosivdAnoitpmusnoChsiF ecruoStniopnoN muideM sercA193

tnuoCmrofiloChgiH ecruoStniopnoN hgiH sercA193 4002

)tnemides(daeL ecruoStniopnoN muideM sercA193

)tnemides&eussit(sBCP ,sedicitsepfoesulacirotsiHlairea/ffonurretawmrots

noitisoped

muideM sercA193

yticixoTtnemideS ecruoStniopnoN muideM sercA193

)tnemides(cniZ ecruoStniopnoN muideM sercA193

yeRledaniraMhcaeBrobraH

serusolChcaeB ecruoStniopnoN hgiH selim92.0 3002

tnuoCmrofiloChgiH ecruoStniopnoN hgiH selim92.0 3002

ecruoS ,sreenignEfosproCymrA.S.U: ydutSytilibisaeFkeerCanollaBdnayeRledaniraM 3002,


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EXIS

TIN

G C

ON

DIT

ION

S

3-2ELB

ATstne

mriapmI

)d(303dehsreta

WkeerC

anollaBrof

sdlohserhTyrotalugeRlatne

mnorivnEdetaicoss

Atne

mriapmI

aideM

esUlaicifeneBrete

maraProtacidnI

eulaVstinU

ecruoSseto

N

keerCanollaB

muimda

Ctne

mideSefiL

citauqA

muimdac

6.14/

6.9).t

wyrd(

mppLEPlF

/MRE

AA

ON

1

Ameh

CeussiT

efiLcitauq

Atneutitsnoc

Ameh

Cyna

001).t

wtew(

bppenilediu

GS

AN

2

enadrolhC

eussiTefiL

citauqA

enadrolhc0.8

).twte

w(bpp

LRTM

BCR

WS

reppoC

devlossiD

retaW

efiLcitauq

Areppoc

devlossid9

L/guC

CC

RTC

3

TD

DeussiT

efiLcitauq

AT

DD-'p,p

0.23).t

wtew(

bppLRT

MB

CRWS

nirdleiD

eussiTefiL

citauqA

nirdleid56.0

).twte

w(bpp

LRTM

BCR

WS

sesuriV

ciretnEreta

W1-

CER?

??

?

tnuoC

mrofiloC

hgiH

retaW

1-CER

mrofiloclacef002

lm001/

NPM

OQ

WPB

4

daeLdevlossi

Dreta

WefiL

citauqA

daeldevlossid

5.2L/gu

CC

CRT

C5

sBCP

eussiTefiL

citauqA

sBCPlatot

3.5).t

wtew(

bppLRT

MB

CRWS

Hpreta

WefiL

citauqA

Hp5.8-5.6

--O

QW

PB

yticixoTtnemideS

tnemideS

efiLcitauq

Alavivrus

dopihpma

----

OQ

WPB

6

muineleSlatoTreta

WefiL

citauqA

muineleslatot0.5

L/guC

CC

RTC

revliStne

mideSefiL

citauqA

revlis77.1

/7.3

).tw

yrd(mpp

LEPlF/

MREA

AO

N6

yticixoTreta

WefiL

citauqA

tnemssessa

yticixot--

--O

QW

PB7

hsarTreta

W2

CER,efiLcitauq

A--

----

OQ

WPB

8

cniZdevlossi

Dreta

WefiL

citauqA

cnizdevlossid

811L/gu

CC

CRT

C9

yrautsEanollaB

enadrolhC

eussiTefiL

citauqA

enadrolhc3.8

).twte

w(bpp

LRTM

BCR

WS

enadrolhC

tnemideS

efiLcitauq

Aenadrolhc

97.4/

6).t

wyrd(

bppLEPlF

/MRE

AA

ON

01

TD

Dtne

mideSefiL

citauqA

TD

D-'p,p7.15

/1.54

).tw

yrd(bpp

LEPlF/

MREA

AO

N11

tnuoC

mrofiloC

hgiH

retaW

1-CER

mrofiloclacef002

lm001/

NPM

OQ

WPB

21

daeLtne

mideSefiL

citauqA

dael2.211

/812

).tw

yrd(mpp

LEPlF/

MREA

AO

N31

sH

APtne

mideSefiL

citauqA

sH

APlatot177,61

/297,44

).tw

yrd(bpp

LEPlF/

MREA

AO

N41

sBCP

eussiTefiL

citauqA

sBCPlatot

3.5).t

wtew(

bppLRT

MB

CRWS

sBCP

tnemideS

efiLcitauq

AsB

CPlatot8.881

/081

).tw

yrd(bpp

LEPlF/

MREA

AO

N51


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EXIS

TIN

G C

ON

DIT

ION

S

3-2ELB

AT)deunitnoc(

stnemriap

mI)d(303

dehsretaW

keerCanollaB

rofsdlohserhT

yrotalugeRlatnemnorivnE

detaicossA

tnemriap

mIaide

MesUlaicifeneB

retemaraP

rotacidnIeulaV

stinUecruoS

setoN

yticixoTtnemideS

tnemideS

efiLcitauq

Alavivrus

dopihpma

----

OQ

WPB

61

gnitsevraH

hsifllehSyrosivd

Areta

Wgnitsevra

HhsifllehS

mrofiloclacef07

lm001/

NPM

OQ

WPB

71

cniZtne

mideSefiL

citauqA

cniz172

/014

).tw

yrd(mpp

LEPlF/

MREA

AO

N81

sdnalteW

anollaB

noitategeVcitoxE

--tatiba

Hdnalte

W--

----

OQ

WPB

91

snoitaretlAtatiba

H--

tatibaH

dnalteW

----

--O

QW

PB02

noitacifidomordy

H--

tatibaH

dnalteW

----

--O

QW

PB12

gnihsulFladiTdecudeR

--tatiba

Hdnalte

W--

----

OQ

WPB

22

hsarTreta

Wtatiba

Hdnalte

W--

----

OQ

WPB

32

SETO

Ntne

mriapmi

enimreted

otdesu

sdlohserhto

wtfo

rewoL.1

,enadrolhc,nirdleid,nirdlasedulcni

sedicitsepfo

puo rgA

mehC.2

,)enadnilgnidulcni(

HC

H,edixoperolhcatpeh,rolhcatpeh,nirdne

enehpaxotdna

naflusodneL/g

m001

fosse ndrah

semussa

CC

C.3egnahc

ottcejbusnoitangised

1-CER;nae

mgol

yad-03.4L/g

m001

fossendrah

semussa

CC

C.5evitcejb

Oevitarra

Nno

desaB.6tne

mriapmi

enimreted

otdesu

sdlohserhto

wtfo

rewoL.7

evitcejbO

evitarraN

nodesaB.8

evitcejbO

evitarraN

nodesaB;etelp

mocL

DMT.9

L/gm

001fo

ssendrahse

mussaC

CC.01

tnemriap

mieni

mretedot

desusdlohserht

owt

f ore

woL.11tne

mriapmi

enimreted

otdesu

sdlohserhto

wtfo

rewoL.21

naem

golyad-03.31

enimreted

otdesu

sdlohserhto

wtfo

rewoL.41

tnemriap

mieni

mretedot

desusdlohserht

owt

fore

woL.51tne

mriapmi

enimr eted

otdesu

sdlohserhto

wtfo

rewoL.61

tnemriap

mievitcejb

Oevitarra

Nno

desaB.71naide

myad-03.81

enimreted

otdesu

sdlohserhto

wtfo

rewoL.91

tnemriap

mievitcejb

Oevitarra

Nno

desaB.02evitcejb

Oevitarra

Nno

desaB.12evitcejb

Oevi tarra

Nno

desaB.22evitcejb

Oevitarra

Nno

desaB.32evitcejb

Oevitarra

Nno

desaB.42

SMRET

FO

NOITI

NIFED

OQ

WPB

evitcejbO

ytilauQ

retaW

nalPnisaB

=

CCCRTC

suounitnoC

airetirC

eluRscixoT

ainrofilaC

=)re ta

whserf(noitartnecno

C

MREA

AO

N,seulav

naideM-egnaR

stceffEA

AO

N=

eniraM

niyticixoT

gnitciderP,5991,.la.tegno L

nodesab

,senilediuG

ytilauQtne

mideSlaciremu

Nhti

wstne

mideS727-417:)4(71,yrtsi

mehC

dnaygolocixoTlatne

mnor ivnE

LEPlFno

desab,leveLstceffE

elbaborPadirolF

=fotne

mssessA

ehtot

hcaorppA,4991,.la.te

dlanoDca

Mrof

deraper P,sretaWlatsao

CadirolF

niytilau

QtnemideS

,.dtL,secivreSlatnemnorivnE

dlanoDca

M,REDlF

eht.

C.B,htimsydaL

LRTM

BCRWS

sleveLeudiseR

eussiT.xaM

BCR

WSa

C=

cixoTdna

hctaWlessu

MetatS

ehtrof

depolevedmargorP

gnirotinoM

ecnatsbu S

enilediuG

SA

Ndedne

mmoceR

3791E

AN/S

AN

=snoitartnecno

CeussiT

mumixa

M


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Figure 2-7 Trash Removed from Mouth of Ballona Creek, 2002SOURCE: Debris Collection Report as M.H. email attachment. Provided by Brian White, Watershed Management Division, LADPW

4-2ELBATgnidaoLtnatulloPrehtaeWteWlacipyT

dehsretaWkeerCanollaB

tnanimatnoC )gK(daoLlaunnA

muimdaC 7

muimorhC 261

reppoC 180,1

daeL 183

yrucreM 81

lekciN 481

muineleS 61

sdiloSdednepsuS 225,3 )snoTcirteM(

cniZ 109,6

ecruoS : ordePnaSotstnanimatnoCfosecruoSdesab-dehsretaW3002,sdnerTdnasnrettaP:yeRledaniraMdnayab

Based on the water quality impairments identified aboveand the results of various monitoring efforts, the SouthernCalifornia Coastal Water Research Project (SCCWRP)has modeled wet weather pollutant loadings for variouscontaminants, as shown in Table 2-4.

Sediment testing has been conducted numerous timesin Marina del Rey and the entrance channel. Althoughno sediments have been measured that have levels ofchemical contaminants high enough to qualify ashazardous to humans under the California HazardousWaste Control Law, some pollutant levels may be highenough to have negative effects on aquatic organisms.Elevated levels of chemicals were generally highest inthe areas with finest particle size, particularly near thecenter of the main entrance channel and the shoals nearthe foot of the breakwater in front of and at the BallonaCreek mouth.


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Based on data collected during snapshot dry weathersampling events in 2003, the mean concentration andload, temporal variability, and spatial distribution ofmetals and bacteria in the open portion of Ballona Creekhave been analyzed by SCCWRP. Although metalsconcentrations were below chronic criteria (for a humanhealth hazard) under the California Toxics Rule, in almostall of the in-river samples, bacteria concentrations at themajority of storm drains and in-river sites wereconsistently above applicable standards. In general, theCreek was found to exhibit a bimodal distribution ofelevated metals and bacteria, with the highest levelsoccurring immediately upstream of the tidal portion ofthe Creek and another area of elevated levels below thelocation where Ballona Creek daylights from anunderground storm drain to an exposed channel (withlower levels in between). These two portions of BallonaCreek correspond to locations where storm drains withconsistently high concentrations and loads discharge tothe Creek (e.g., Sepulveda Channel and BenedictCanyon). Modeling performed for the Army Corps ofEngineers suggests that elevated hydrocarbon levels arefound in the Sepulveda Wash (although elevated levelswould also be expected in areas with current and/orhistoric oil production). This suggests for somepollutants, source reduction and treatment efforts couldbe focused on subwatersheds drained by specifictributaries.

A study of the effect of stormwater and urban runoffdischarge into Santa Monica Bay (Bay 1999) found thefollowing:

� Virtually every sample of Ballona Creek stormwatertested was toxic to sea urchin fertilization.

� The first storms of the year produced the most toxicstormwater in Santa Monica Bay during the study.

� The toxic portions of the stormwater plume werevariable in size, extending from ¼ to 2 milesoffshore of Ballona Creek.

� Surface water toxicity caused by unidentifiedsources was frequently encountered during dryweather in Santa Monica Bay.

� Copper and other unidentified constituents mayalso be responsible for some of the toxicity measuredin Santa Monica Bay.

� The measured concentrations of zinc and copper inBallona Creek stormwater were estimated to accountfor only 5 to 44 percent of the observed toxicity.

� Sediments offshore of Ballona Creek generally hadhigher concentrations of urban contaminants,including common stormwater constituents suchas lead and zinc.

� Sediments offshore of Ballona Creek showedevidence of stormwater impacts over a large area.

A study by the County of Los Angeles found that in1995/96, the highest fecal coliform readings at fivestations coincided with the largest storm of the season,while in 1996/97, the highest fecal coliform readings attwo stations coincided with the first storm of the seasongreater than 0.1 inch rainfall (LACDPW 2000). Theseobservations suggest that peak fecal coliform levels maybe related to hydrologic conditions that occur across thewatershed (e.g., rainfall patterns), and not just land useor other conditions in individual tributaries.

GROUNDWATER QUALITY

Information on groundwater quality under most of theWatershed is limited, as only the cities of Beverly Hillsand Santa Monica use groundwater for domestic watersupplies. In the Hollywood subbasin, water from onepublic supply (tested in 1998) showed a Total DissolvedSolid (TDS) content of 526 mg/L. In the Santa Monicasubbasin, water samples from 7 public supply wellsindicate an average TDS content of 916 mg/L and a rangeof 729 to 1,156 mg/L. High TDS levels begin to interferewith the use of water between 500 and 1,000 mg/L. At1,000 mg/L, water is considered brackish and unusable.High TDS levels are commonly referred to as “hard”water, which contributes to the formation of calciumand other deposits on shower walls and other surfacesregularly exposed to water. Sometimes, high TDS wateris mixed with low TDS sources (such as imported water)to make the water more usable for domestic purposes.


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In addition to high levels of dissolved solids (commonthroughout most of Southern California), othercontaminants from urban land uses may be present ingroundwater. In urbanized areas, these may includevolatile organic compounds, hexavalent chromium (orChromium 6), and N-nitrosodimethylamine (NDMA)from industrial activities and nitrates from the use offertilizers and septic tanks. In the early 1990s, the Stateof California mandated upgrades to undergroundgasoline storage systems to prevent leakage of gasolineand migration to groundwater. In 1996, the discoveryof a gasoline additive, Methyl Tertiary Butyl Ether(MTBE) in groundwater extracted from wells in the Cityof Santa Monica indicated that such systems may notalways be effective. The contamination prompted ashutdown of city wells and ultimately resulted inlegislation mandating the removal of MTBE fromgasoline. However, the extent of possible MTBEcontamination in soil and/or groundwater in theWatershed is currently unknown.

SOURCES OF WATER POLLUTION

As indicated in the Los Angeles Regional Board’s 1994Basin Plan, pollutants degrading the beneficial uses canbe categorized into point source pollutants and nonpointsource pollutants. Pollutants from point sources aretransported to water bodies in controlled flows at well-defined locations, such as discharges from wastewatertreatment facilities or industrial sites. Pollutants fromnonpoint sources are diffuse, both in terms of their originand mode of transport to surface and ground waters.These pollutants are transported to waters by runoff fromprecipitation, irrigation, and atmospheric deposition.

As there are no wastewater treatment facilities in theWatershed, even with approximately 150 point sourcesin the Watershed, nonpoint sources are the primarycontributor to most of the water quality impairments inthe Creek and associated water bodies. Occasionaloverflows from the Hyperion treatment system (greatlyreduced in recent years) and illicit sewer connections tothe storm drain system contribute to the presence of

contaminants in both stormwater and dry season flows.Typical pollutants in runoff include urban debris (ortrash), suspended solids, bacteria, viruses, heavy metals,pesticides, petroleum hydrocarbons, and other organiccompounds (LARWQCB 1994).

The sources of contaminants in stormwater and dryweather runoff vary widely, from industrial andcommercial uses, fueling and maintenance facilities,transportation facilities (including highways and streets),maintained open spaces (such as parks and golf courses)and residential land uses. In addition, sediment fromexposed land surfaces (such as vacant land andconstruction sites) and atmospheric deposition ofpollutants (from vehicles and aircraft, constructionactivities, and industrial sources) represent additionalsources of contaminants.

The County of Los Angeles has identified light industrial,transportation, and retail/commercial land uses asproducing the highest median concentrations for totaland dissolved zinc in runoff. Light industrial andtransportation land uses displayed the highest medianconcentrations for total and dissolved copper, and lightindustrial produced the highest concentrations ofsuspended solids. Runoff concentrations from theremaining land use types (high-density single-familyresidential, education, multifamily residential, and mixedresidential) were significantly less. As part of this effort,metal fabrication businesses were identified as producingthe highest median concentrations for zinc, copper, andsuspended solids (LACDPW 2000).

Pesticides and insecticides that find their way into thewaters often stem from their use in lawns and gardensthroughout the cities in the watershed. Similar to metals,the introduction of pesticides and insecticides into thewaters of the watershed via urban runoff can result insediment and water column toxicity. Pesticides that mixor dissolve in the water often remain toxic and canadversely affect the health of organisms living in the watersuch as fish, shrimp, and algae.


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Organic compounds affecting the beneficial uses of thewaters in the Watershed include polychlorinatedbiphenyls (PCBs), polynuclear aromatic hydrocarbons(PAHs), and dichloro-diphenyl-trichloroethane (DDT).PCBs were used in transformer oils as a heat-exchangemedium in the past and have since been banned fromuse due to their toxic, bioaccumulative, and extremelystable properties in the environment. Although there arestill many transformers currently in use that containPCBs, over time, these transformers will be replaced inresponse to regulatory mandates and/or routinereplacement activities. PAHs are the byproducts of thecombustion of refined petroleum products or the burningof biomass fuels (e.g., wood fires), or leach from refinedpetroleum products (e.g., asphalt, creosote, or spilledmotor oils). The primary sources of PAHs in theWatershed are vehicles, aircraft, and other engines fueledwith gasoline or diesel fuel, which results in aerialemissions. DDT, a widely used and long-lasting pesticidethat was banned in 1972, still remains present instormwater and dry-weather runoff in the Creek.

Coliforms serve as indicator organisms for water qualitysampling. Indicator organisms are nonharmful organismsthat are associated with disease-producing or pathogenicorganisms (Stenstrom 1999). High coliform counts canindicate the presence of high concentrations ofpathogenic bacteria, viruses, and protozoans. As waterfrom Ballona Creek discharges into Santa Monica Bay,beach closures may occur when bacterial indicator levelsat the beaches are too high, which may present a serioushealth risks to swimmers. In addition, high levels ofpathogenic organisms can also result in health risks tohumans associated with the consumption of the localseafood. According to the draft bacteria TMDL for SantaMonica Bay, elevated levels of bacterial indicators maybe due to sanitary sewer leaks and spills, illicitconnections of sanitary lines to the storm drain system,runoff from homeless encampments, illegal dischargesfrom recreational vehicle holding tanks, malfunctioningseptic tanks, and fecal matter from animals and birds.

Urban debris, or trash, may be present in both stormwaterand urban runoff and includes material suspended inthe water column and floating material. Floatables caninhibit the growth of aquatic vegetation, decrease habitatsfor fish and other living organisms, and cause harm towildlife through ingestion of, or entanglement with thesematerials. Some debris, including diapers, medical andhousehold waste, and chemicals, are also a source ofbacteria and toxic substances. The source of thesematerials is human activity, in the form of litter, and thedeposition of leaves and grass clippings on sidewalks andgutters and their subsequent transport into the stormdrain system.

Studies of Marina del Rey indicate that Ballona Creek isthe largest contributor of sediments and associatedchemicals in the marina, with minor contributions fromOxford Basin, the Washington Boulevard drain, andmarine activities. Oxford Basin discharges into Basin Eat the back of the marina, while the WashingtonBoulevard drain empties into the harbor via BallonaLagoon. Basin E has been found to have elevated levelsof contaminants, which could come directly from thedischarges of Oxford Basin or could have originated fromBallona Creek and were carried back into Basin E withfine sediments. The primary source of chemicals to themarina during the dry season is from marine activitiessuch as boating, oil spills, overboard waste disposal,antifouling paint (which contain copper and are designedto slough off over time), and sacrificial zinc anodes(USACE 2003), which suggests changes in boating andmaintenance practices can reduce these sources.

Because much of the monitoring to date has been limitedin a spatial or temporal sense, many of the conclusionsregarding the sources of contaminants are rather general.


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Although sources of some contaminants have beensuggested, identification of the specific location of thesesources is hampered by a lack of definitive monitoringdata and an inadequate understanding of the storm drainsystem. As a result, although individual drains thatdischarge into the Ballona Creek channel have beenidentified as a source of elevated levels of contaminants,an understanding of the precise area drained by eachdrain varies by jurisdiction and location, and thusidentifying sources of contamination along individualtributaries will be important to developing sourcereduction and/or treatment programs.

G. HABITAT

Because of extensive urbanization, few natural areasremain within the Ballona Creek Watershed. Over thepast two centuries, common practices in ranching,farming, and landscaping have resulted in theintroduction of a vast array of nonnative plants andanimals. As a result, most natural or vacant areas in theWatershed include a mix of native and nonnative species.The proximity of undeveloped and natural spaces tohumans can result in regular or occasional disturbance(including pets, passive recreation and brush clearancefor fire safety), which further reduces the value of thesespaces as habitat, particularly to sensitive native plantand animal species.

View across Ballona Wetlands


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Historically, plant communities within the Watershedincluded coastal dunes, salt marsh, native grasslands,coastal sage scrub, chaparral, coast live oak woodland,California walnut woodlands, freshwater marsh, andriparian woodlands. Given the wide range of plantcommunities, native fish, birds, mammals, reptiles,amphibians, and insects were abundant. Fossils recoveredfrom La Brea Tar Pits provide ample evidence of manysuch creatures in the Watershed over the millennia.

Remnants of historically occurring plant communitiescan be seen in the natural and semi-natural areas of theWatershed, including the Ballona Wetlands, the BallonaLagoon complex, the Baldwin Hills, and the undevelopedportions of the Santa Monica Mountains (includingseveral mostly natural parks, such as Griffith Park andRunyon Canyon Park). Small pockets of undevelopedland also provide home to naturally occurring plants,but the extent of human disturbance often limits thevalue of these spaces as habitat. Fragmentation of habitatcreates substantial barriers to the migration of plantsand animals, which over time can reduce species diversityand populations.

Invasive species are found throughout the Watershed.An “invasive species” may be defined as a nonnativespecies that causes or is likely to cause economic orenvironmental harm or harm to human health. Invasivespecies can be plants, animals, and other organisms (e.g.,microbes). Human actions are the primary means ofinvasive species introductions. In the Watershed, nearlyall of the annual grasses on undeveloped lands arenonnative species that replaced native perennial grasseslong ago. Other common invasive species in theWatershed include tree tobacco (Nicotiana glauca), anative of Argentina, and several species of nonnative weedsincluding Russian thistle (Salsola tragus), castor bean(Ricinus communis), broom (Spartium sp.), and pampasgrass (Cortaderia sellanoa). One highly invasive speciescommonly found in streams in the region, giant reed(Arundo donax), is found in only limited locations inthe Watershed, probably due to the lack of riparianhabitat.

The last remaining areas of native habitat in theWatershed are summarized below.

1. Santa Monica Mountains

Part of the Transverse Ranges, the Santa MonicaMountains stretch from Point Mugu in Ventura Countyto the Hollywood and Elysian Hills. Historically, themountains supported a diverse range of habitats,including coastal sage scrub, chaparral, coast live oakwoodland, riparian woodlands, and freshwater marshesadjacent to perennial springs. Given the diversity ofhabitats and microclimates, a diverse array of bird,mammals, reptiles, amphibians, and insects would havebeen found in the headwaters of the Ballona CreekWatershed.

Runyon Canyon Park


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In 1896, Colonel Griffith J. Griffith deeded 3,015 acresof his Rancho Los Feliz estate to the City of Los Angeles(the park was later expanded to 4,107 acres).Development of the Hollywood Hills began early in thetwentieth century. The Hollywood (land) sign waserected in 1923 and the Mulholland Highwaycompleted in 1924, making most of the southern slopeof the Santa Monica Mountains (within the Watershed)accessible for residential development. Residentialdevelopment required roads, building pads, and utilities,including water. Over time, the remaining undevelopedareas in the mountains were limited to steep slopes andremote canyons. The modification of hillslopes, fillingof canyons, and the increased extent of impervioussurfaces altered runoff patterns, leading to channelizationof streams in the canyons to protect lives and property.Widespread landscaping introduced nonnative andinvasive species throughout the mountains, includingplants that thrive on the year-round runoff created byirrigation of yards and gardens.

Today, because of the extensive residential development,natural habitat in the Santa Monica Mountains withinthe Ballona Creek Watershed is limited and fragmented.Natural areas include large portions of Griffith Park andRunyon Canyon Park, and portions of Laurel CanyonPark and Beverly Glen Park. A large area around Upperand Lower Franklin Canyon Reservoirs is preserved aspart of the Santa Monica Mountains National RecreationArea. In addition, the City of Los Angeles managesundeveloped areas around the Hollywood and StoneCanyon Reservoirs. Remaining natural areas are locatedon private land, much of which may be too steep fordevelopment.

That portion of the Santa Monica Mountains withinthe Watershed provides habitat for many mammals, birds,reptiles, and invertebrates. Larger mammals, includingthe coyote and deer are limited to more remote areas,while rabbits, ground squirrels, mice, and the opossum

are found throughout the area. Birds include warblers,sparrows, hawks, owls, and jays, along with species foundthroughout the coastal plain, such as the northernmockingbird, house finch and spotted and mourningdoves.

The Santa Monica Mountains Conservancy territoryincludes that portion of the Watershed generally northof Sunset Boulevard, except for that portion within theCity of Beverly Hills. The Conservancy has acquiredparkland and open space and preserved remaininghabitat in several locations in the mountains. In 2002,residents of the City of Los Angeles that reside in theSanta Monica Mountains approved the formation of theSanta Monica Mountains Open Space PreservationAssessment Districts (Nos. 1 and 2). The districts willacquire and preserve additional open space, wildlife areas,and natural lands and protect important habitat andwildlife corridors in the Santa Monica Mountains in theCity of Los Angeles.

2. Baldwin Hills

The undeveloped areas of the Baldwin Hills cover anarea of approximately 1400 acres of which one-third iscurrently developed as parkland and two-thirds (950acres) is in private ownership, primarily supporting oiland gas production. Existing parks include the KennethHahn State Recreation Area, the Ladera Ball Fields, theVista Pacifica Scenic Site, Culver City Park, and NormanO. Houston Park.

The major plant communities in the Baldwin Hillsinclude coastal scrub,4 annual grasslands, and somelimited riparian areas. The coastal scrub community lackssome of the typical plant species found in the coastalsage scrub community, which may suggest this plantcommunity is in decline, with nonnative speciesreplacing historically occurring plants. The annualgrasslands are primarily composed of nonnative and

4 Due to the absence of a dominant sage species of the genus Salvia in theBaldwin Hills, this community is termed coastal scrub, instead of the morecommon coastal sage scrub.


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invasive species, typical of most grasslands in SouthernCalifornia. The riparian areas are very limited and includeonly a limited number of plant species typically associatedwith riparian vegetation in the region. Riparian vegetationmay be supported by runoff from landscape irrigation,although some areas could be supported by groundwaterseeps. Invasive plants also represent an issue in this area,with pampas grass the most visible.

Animal populations in the Baldwin Hills reflect thedegraded nature of existing vegetation and the extent ofhuman disturbance. The coastal California gnatcatcher(Polioptila californica), a Federal listed threatened species,was reported in the Baldwin Hills in 1980. TheTricolored Blackbird (a California State Species of SpecialConcern) has been observed recently and the Pallid Bat,Western Mastiff Bat and the Los Angeles Pocket Mouse(also State Species of Special Concern), may be found inthe Baldwin Hills (Molina 2001). The absence of thecoyote from the Baldwin Hills and the presence of feraldogs and cats have altered traditional predation patterns,which in turn have adversely affected small birds andother small vertebrates.

Because remaining habitat is generally limited to theeastern and western edges of the Baldwin Hills (in areasin both public and private ownership), fragmentationof this habitat represents an issue for long-term geneticdiversity and population viability. The Baldwin HillsConservancy, created in 2000, is charged to acquire anddirect the management of public lands within theBaldwin Hills area. Existing biological resources havebeen cataloged in the Biota of the Baldwin Hills,published by the Natural History Museum of LosAngeles County. The Baldwin Hills Park Master Planidentifies opportunities for restoration of habitat,including the creation of wildlife corridors within theBaldwin Hills and to Ballona Creek, which runs justnorth of the Baldwin Hills Scenic Overlook.

3. Riparian

Due to the extensive hydrologic modification of theWatershed, riparian vegetation along Ballona Creek andtributary streams is virtually nonexistent on the coastalplain. Concrete lined storm drains provide noopportunities for the establishment of historicallyoccurring trees and plants that supported birds,mammals, insects, amphibians and fish (in locations withperennial water). Thus, existing riparian habitat in theWatershed is limited to small areas in the Baldwin Hills,primarily in canyon bottoms, along the base of slopes(where heavy soils retain moisture) and along tributarystreams in upper portions of the Santa MonicaMountains.

Bronson Canyon, Griffith Park


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Ballona Lagoon

4. Vacant/Undeveloped Lands

As noted above, historical practices in ranching, farmingand landscaping have introduced a wide array ofnonnative and invasive species in the Watershed. As aresult, most undeveloped or vacant land supports bothnative and nonnative species representative of two plantcommunities: ruderal and annual grasslands. The ruderalplant community is also known as a weedy plantcommunity. It is characterized by periodic or constantdisturbances such as weed control, heavy vehicle use,disking, controlled or uncontrolled burning, and similardisruptive activities. Ruderal plant communities aregenerally found in flat open areas, with the plant speciesdominated by native and introduced weed species highlyadapted to disturbance. The annual grassland plantcommunity occurs primarily on heavy soils and generallyflat topography. Because annual grasslands includespecies introduced long ago, it is considered an invasiveplant community that has replaced the perennialgrasslands formerly found in California. As an invasiveplant community, it is tolerant of disturbance, and isgenerally found in areas that are similar to ruderal habitatsbut that are undergoing fewer disturbances.

Undeveloped areas on the coastal plan provide foraginghabitat for various birds, including raptors such as hawksor owls (especially in areas close to the hills) variousreptiles and small mammals. However, most wildlifespecies found in these areas are tolerant of human activityand may also occur in landscaped areas such as parksand in backyards.

5. Ballona Wetlands / LagoonComplex

Historically, Ballona Creek met the Pacific Ocean in amosaic of marine tidal channels and lagoons, coastaldunes, brackish pools, perennial riparian habitat,freshwater marshes, and dry upland areas. This complexcovered more than 3,000 acres, of which about 1,000acres were lagoons that were heavily influenced by tidalregimes and flood flows. This diverse and productiverange of habitats would have supported a wide array ofaquatic and terrestrial plants and animals.


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Human impacts on the wetlands/lagoon complex beganin the late 1800s, with the development of severalhunting lodges, resorts, and a railroad. In the early 1900s,the Pacific Electric Railroad (the “red cars”) was extendedto Playa del Rey and road development began in thearea. Real estate developments in Venice and Playa delRey began to encroach upon the wetlands. Thechannelization of Ballona Creek in 1935 restricted waterflow, and the wetlands and lagoons began to dry up.From the 1930s into the 1950s, oil derricks wereconstructed throughout the area and large portions ofthe wetlands were diked, drained, or developed intoartificial ponds. The development of Marina del Rey inthe late 1950s removed a large portion of the remainingwetlands. As a result, the wetlands shrank to less than200 acres, about 10 percent of the original area.

The State-listed endangered Belding’s savannah sparrow(Passerculus sandwichensis beldingi) breeds in the Ballonawetlands. The Federal and State listed endangeredCalifornia least tern (Sterna antillarum browni) breedson nearby Venice Beach (within a fenced reserve area)and forages in the lagoons and channels of the Ballonawetlands. Other listed species that do not breed in thearea but forage in the Ballona wetlands include theFederal listed threatened western snowy plover(Charadrius alexandrinus nivosus), the State listedendangered American peregrine falcon (Falco peregrinusanatum), and the California brown pelican (Pelecanusoccidentalis californicus).

The precise current extent of the Ballona Wetlands iscomplicated. Until recently, only one parcel ofundeveloped land (Area B, south of Ballona Creek andnorth of Culver Boulevard) was usually identified as theBallona Wetlands. Tidal flushing was recently restoredto the central portion of this area. In 2001, the State ofCalifornia chose to retain Area C (north of Ballona Creekand east of Lincoln Boulevard) as part of a tax settlement.Fill material was deposited in Area C during constructionof the flood control channel in the 1930s and againduring construction of Marina del Rey. In 2003, a

freshwater marsh was completed (south of JeffersonBoulevard and west of Lincoln Boulevard), into whichstormwater runoff from Playa Vista and the JeffersonDrain is discharged. The State of California recentlypurchased 483 acres, which could further expand thearea of former wetlands available for restoration. A mapshowing the recent land acquisition in the BallonaWetlands is provided in Figure 2-8.

The bluffs above the Ballona Wetlands historicallysupported coastal prairie habitat, which has been mostlyeliminated in coastal Los Angeles. The slopes (also knownas the Ballona Escarpment) support degraded stands ofcoastal sage scrub, although invasive species andornamentals introduced to control erosion have greatlylimited the extent of native vegetation.

Historic development in the area has also greatly reducedthe extensive network of tidal lagoons, leaving onlyBallona Lagoon (which provides a water connection tothe Venice Canals) and Del Rey Lagoon, south of theBallona Creek channel. Tidal flushing to both lagoons isconstrained to reduce high water during flood events.Del Rey Lagoon is located within Del Rey Lagoon Park,and is mostly surrounded by lawn areas, although aproposed project would remove invasive plants andreplant native vegetation on the east and west banks ofthe lagoon.


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Figure 2-8 Ballona Wetlands AcquisitionADAPTED FROM: California Coastal Conservancy


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Ballona Lagoon and the Venice Canals are generally linedby residential development. Vegetative restoration workalong the east bank of Ballona Lagoon has replacednonnative vegetation; however, restoration work remainsto be completed along the western bank. Other recentimprovements in the lagoon have expanded the area ofmudflats and limited public access. The City of LosAngeles has also proposed improvements to the GrandCanal (the connection between Ballona Lagoon and theVenice Canals), including new storm drains, planting ofnative vegetation and improved walkways.

Along the northern edge of Marina del Rey, OxfordLagoon (also known as the Oxford Flood Control Basin)was designed as a stormwater detention basin with atidal gate to restrict tidal interchange. The lack of tidalflushing results in poor water quality and high bacterialevels, which then impacts water quality in the adjacentBasin E in Marina del Rey. The Oxford Lagoon is fencedto limit public access and is generally surrounded bynonnative trees and shrubs. The lack of public accessand presence of year-round water attracts a wide rangeof bird species.

Marina del Rey, the adjacent lagoons, the central portionof Area B of the Ballona Wetlands (where partial tidalflushing was recently restored) and Ballona Creek providea variety of salt-water, estuarine, and mudflat habitats,which support shore birds and migratory waterfowl (someof which were noted above) and a variety of fish andinvertebrates. However, the lack of tidal flushing in thelagoons and associated water bodies, and poor waterquality in Marina del Rey and Ballona Creek, limits thenumber and diversity of fish, birds, and other creaturessupported by these aquatic habitats.

Oxford Flood Control Basin

The discharge of stormwater and urban runoff fromBallona Creek into Santa Monica Bay reduces waterquality and clarity within the nearshore areas of the bayand results in the deposition of sediment (with varyingtoxicity) at the mouth of the creek. Stormwater andurban runoff may also be toxic to some forms of aquaticlife in Santa Monica Bay, due to the presence of metals,such as zinc, and other urban contaminants.


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5-2ELBATdehsretaWkeerCanollaBehtnihtiwesUdnaL

esUdnaL sercAlatoT sercAlatoTfotnecreP

ylimaF-elgniS 940,83 %7.54

ylimaF-itluM 699,41 %0.81

laicremmoC 466,6 %0.8

cilbuP 840,3 %7.3

lairtsudnIthgiL 173,3 %0.4

nabrUrehtO 929,2 %5.3

nepO 478,31 %7.61

nwonknU 653 %4.0

latoT 782,38 %0.001

ecruoS : retaWmrotSfostcapmIcimonocEdnalaicnaniF,snartlaC8991,dehsretaWkeerCanollaB,tnemtaerT

H. LAND USE

The Watershed is comprised of the Cities of Beverly Hills,Culver City, and West Hollywood and parts ofInglewood, Los Angeles and Santa Monica and small-unincorporated areas of Los Angeles County. Thepopulation in the Watershed is approximately 1.6 millionpeople (Braa et al. 2001).

Caltrans estimated land uses in the Watershed basedupon information from the Southern CaliforniaAssociation of Government (SCAG). As shown inTable 2-5, the predominant land use in the Ballona CreekWatershed is residential, representing 63.7 percent ofthe total land area, including multi-family residentialuses covering 18 percent of the area. Although open areasrepresent 16.7 percent, this category may include parksand other open areas not generally open to the public,including vacant land and golf courses. Figure 2-9 showsland use in the Watershed.


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SOURCE: SCAG 1993 Land Use, 1996; EIP Associates, GIS, July 14, 2003

Figure 2-9 Land Use in the Ballona Watershed

Documents

CHAPTER| - Department of Public Works, Los Angeles …dpw.lacounty.gov/wmd/watershed/bc/bcmp/docs/sept04...Centinela Avenue to approximately Venice Boulevard, and then zigzags southwest