WATERSHED CROSSINGS BY POSTMILE
Caltrans District 7 GIS Branch and Robert Wu, D7 Stormwater Liason, April 5, 2011.  Notes at end.
CO/RTE/PM LEAVING ENTERING POS COMMENT
LA 001 PM  00.000 Begin County San Gabriel River C  
LA 001 PM  00.190 San Gabriel River Los Cerritos Channel and Alamitos Bay C  
LA 001 PM  01.850 Los Cerritos Channel and Alamitos Bay Colorado Lagoon C  
LA 001 PM  02.740 Colorado Lagoon Los Cerritos Channel and Alamitos Bay C  
LA 001 PM  03.960 Los Cerritos Channel and Alamitos Bay Los Angeles River C  
LA 001 PM  07.700 Los Angeles River Dominguez Channel C  
LA 001 PM  09.240 Dominguez Channel Los Angeles Harbor C  
LA 001 PM  11.220 Los Angeles Harbor Machado Lake C  
LA 001 PM  17.380 Machado Lake JG 6 of Santa Monica Bay C  
LA 001 PM  21.230 JG 6 of Santa Monica Bay JG 5 of Santa Monica Bay C  
LA 001 PM  23.620* JG 5 of Santa Monica Bay Dominguez Channel B  
LA 001 PM  24.920 Dominguez Channel JG 2 of Santa Monica Bay D  
LA 001 PM  25.670 JG 2 of Santa Monica Bay Dominguez Channel D  
LA 001 PM  25.960 Dominguez Channel JG 2 of Santa Monica Bay D  
LA 001 PM  29.220 JG 2 of Santa Monica Bay Ballona Creek C  
LA 001 PM  30.660 Ballona Creek Marina del Rey C  
LA 001 PM  32.180 Marina del Rey JG 3 of Santa Monica Bay C  
LA 001 PM  36.700 JG 3 of Santa Monica Bay JG 2 of Santa Monica Bay C  
LA 001 PM  40.750 JG 2 of Santa Monica Bay JG 1 of Santa Monica Bay C  
LA 001 PM  46.790 JG 1 of Santa Monica Bay Malibu Creek C  
LA 001 PM  47.420 Malibu Creek JG 1 of Santa Monica Bay C  
LA 001 PM  60.080 JG 1 of Santa Monica Bay JG 4 of Santa Monica Bay C  
LA 001 PM  61.500 JG 4 of Santa Monica Bay JG 1 of Santa Monica Bay C  
LA 001 PM  62.800 JG 1 of Santa Monica Bay End Route C  
         
LA 002 PM  02.390 Begin Route JG 3 of Santa Monica Bay C  
LA 002 PM  02.580 JG 3 of Santa Monica Bay Ballona Creek C  
LA 002 PM  03.680 Ballona Creek Route Break C  
LA 002 PM  10.580 Route Restart Ballona Creek C  
LA 002 PM  12.740 Ballona Creek Route Break C  
LA 002 PM  13.100 Ballona Creek Echo Park Lake C 0.11 mile S. of Sunset Blvd.
LA 002 PM  14.350 Echo Park Lake Los Angeles River C 0.1 mile S. of Oak Glen Pl.
LA 002 PM  36.380 Los Angeles River San Gabriel River C  
LA 002 PM  42.900 San Gabriel River Los Angeles River D  
LA 002 PM  49.750 Los Angeles River San Gabriel River D  
LA 002 PM  50.500 San Gabriel River Los Angeles River C  
LA 002 PM  52.830 Los Angeles River Antelope C  
LA 002 PM  62.530 Antelope San Gabriel River D  
LA 002 PM  64.110 San Gabriel River Antelope D  
LA 002 PM  74.700 Antelope San Gabriel River C  
LA 002 PM  78.000 San Gabriel River Antelope D  
LA 002 PM  79.900 Antelope Mojave D  
LA 002 PM  82.260 Mojave End County C  
         
LA 005 PM  00.000 Begin County San Gabriel River C  
LA 005 PM  08.310 San Gabriel River Los Angeles River C  
LA 005 PM  46.700* Los Angeles River Santa Clara River B  
LA 005 PM  87.360 Santa Clara River Grapevine C  
LA 005 PM  88.600 Grapevine End Route C  
         
LA 010 PM R02.155 Begin Route JG 3 of Santa Monica Bay C  
LA 010 PM R03.610 JG 3 of Santa Monica Bay Ballona Creek C  
LA 010 PM  16.570 Ballona Creek Los Angeles River C  
LA 010 PM  30.100 Los Angeles River San Gabriel River C  
LA 010 PM  45.760 San Gabriel River Santa Ana River C  
LA 010 PM  48.200 Santa Ana River End Route C  
LA 010 PM S00.000 Begin Spur Los Angeles River C  
LA 010 PM S00.655 Los Angeles River End Spur C  
         
LA 014 PM  24.800 Begin Route Los Angeles River C  
LA 014 PM  25.500 Los Angeles River Santa Clara River C  
LA 014 PM  53.530 Santa Clara River Antelope C  
LA 014 PM  77.000 Antelope End Route C  
         
LA 019 PM  03.980 Begin Route Los Cerritos Channel and Alamitos Bay C  
LA 019 PM  08.400* Los Cerritos Channel and Alamitos Bay End Route B  
         
LA 022 PM  00.000 Begin Route Colorado Lagoon C  
LA 022 PM  00.960 Colorado Lagoon Los Cerritos Channel and Alamitos Bay C  
LA 022 PM  01.260 Los Cerritos Channel and Alamitos Bay San Gabriel River C  
LA 022 PM  01.467 San Gabriel River End County C  
         
LA 023 PM  06.750 Jurisdiction 1 of Santa Monica Bay Sherwood Lake C 0.05 mile N. of Mulholland
LA 023 PM  07.280 Sherwood Lake Malibu Creek C 0.6 mile N. of Mulholland
LA 023 PM  08.900 Malibu Creek End County C  
         
LA 027 PM  00.000 Begin Route JG 1 of Santa Monica Bay C  
LA 027 PM  09.300 JG 1 of Santa Monica Bay Los Angeles River C  
LA 027 PM  20.060 Los Angeles River End Route C  
         
LA 039 PM 17.900 Begin Route San Gabriel River B  
LA 039 PM 44.400 End Route San Gabriel River B Jct LA 2
         
LA 047 PM  00.000 Begin Route Los Angeles Harbor C  
LA 047 PM  02.302 Los Angeles Harbor Route Break C  
LA 047 PM  03.497 Restart Route Los Angeles Harbor C  
LA 047 PM  04.161 Los Angeles Harbor End Route at SR 103 C  
         
LA 057 PM  00.000 Begin Route San Gabriel River C  
LA 057 PM R08.200 San Gabriel River Puddingstone Lake C  
LA 057 PM R08.950 Puddingstone Lake San Gabriel River C  
LA 057 PM R12.212 San Gabriel End Route C  
         
LA 060 PM  00.000 Begin Route Los Angeles River C  
LA 060 PM  09.570 Los Angeles River Legg Lake C 0.06 mile E. of 164/60 Sep.
LA 060 PM  10.840 Legg Lake Los Angeles River D 0.27 mile W. of Peck Rd.
LA 060 PM  11.000 Los Angeles River San Gabriel River D  
LA 060 PM  27.050 San Gabriel River Santa Ana River C  
LA 060 PM  30.400 Santa Ana River End County C  
         
LA 066 PM  00.000 San Gabriel River Puddingstone Reservoir C Jct Baseline Rd.
LA 066 PM  02.360 Puddingstone Reservoir San Gabriel River C 0.04 mile W. of Williams Ave.
LA 066 PM  04.170 San Gabriel River Santa Ana River C  
LA 066 PM  05.300 Santa Ana River End Route C  
         
LA 071 PM  00.335 Begin Route San Gabriel River C  
LA 071 PM  02.470 San Gabriel River Santa Ana River C  
LA 071 PM  04.785 Santa Ana River End County C  
         
LA 090 PM  00.921 Begin Route Marina del Rey C  
LA 090 PM  01.740* Marina del Rey Ballona Creek B  
LA 090 PM  03.280 Ballona Creek End Route C  
         
LA 091 PM  06.012 Begin Route Dominguez Channel C Entering City of L.A.
LA 091 PM  08.430 Dominguez Channel Los Angeles River C  
LA 091 PM  13.870 Los Angeles River Los Cerritos Channel and Alamitos Bay C  
LA 091 PM  16.050 Los Cerritos Channel and Alamitos Bay San Gabriel River C  
LA 091 PM  20.741 San Gabriel River End County C  
         
LA 101 PM  00.000 Begin Route Los Angeles River C  
LA 101 PM  02.570 Los Angeles River Ballona Creek C  
LA 101 PM  08.900 Ballona Creek Los Angeles River C  
LA 101 PM  29.260 Los Angeles River Malibu Creek C  
LA 101 PM S00.000 Begin Spur Los Angeles River C  
LA 101 PM S01.329 Los Angeles River End Spur C  
         
LA 103 PM  00.000 Begin Route Los Angeles Harbor C  
LA 103 PM  00.880 Los Angeles Harbor Dominguez Channel D  
LA 103 PM  01.700 Dominguez Channel End Route D  
         
LA 105 PM R00.000 Begin Route JG 2 of Santa Monica Bay C  
LA 105 PM R00.500 JG 2 of Santa Monica Bay Dominguez Channel C  
LA 105 PM R06.760 Dominguez Channel Los Angeles River C  
LA 105 PM R17.110* Los Angeles River San Gabriel River B Sump drains all the way back to L.A. River.
LA 105 PM R18.145 San Gabriel River End Route C  
         
LA 107 PM  00.000 Begin Route Machado Lake C  
LA 107 PM  02.250 Machado Lake Dominguez Channel C  
LA 107 PM  03.220 Dominguez Channel JG 8 of Santa Monica Bay D  
LA 107 PM  03.760 JG 8 of Santa Monica Bay Dominguez Channel D  
LA 107 PM  04.794 Dominguez Channel End Route C  
         
LA 110 PM  00.000 Begin Route Los Angeles Harbor C  
LA 110 PM  03.810 Los Angeles Harbor Machado Lake C  
LA 110 PM  06.520 Machado Lake Dominguez Channel C  
LA 110 PM  13.500 Dominguez Channel Los Angeles River C  
LA 110 PM  19.940 Los Angeles River Ballona Creek C  
LA 110 PM  22.900 Ballona Creek Los Angeles River C  
LA 110 PM  31.912 Los Angeles River End Route C  
         
LA 118 PM  00.000* Begin County Los Angeles River B  
LA 118 PM  14.000 Los Angeles River End Route C  
         
LA 126 PM  00.000 Begin County Santa Clara River C  
LA 126 PM  05.822 Santa Clara River End Route C  
         
LA 138 PM  00.000 Begin Route Santa Clara River C  
LA 138 PM  02.400 Santa Clara River Antelope B  
LA 138 PM  74.900 Antelope End County B  
         
LA 164 PM  01.385 Begin Route Los Angeles River C  
LA 164 PM  01.570 San Gabriel River Los Angeles River C  
LA 164 PM  02.800 Los Angeles River Legg Lake D  
LA 164 PM  03.230 Legg Lake Los Angeles River D 0.1 mile S. of 60/164 Sep.
LA 164 PM  08.800 Los Angeles River End Route C  
         
LA 187 PM  03.500 Begin Route Marina del Rey C  
LA 187 PM  03.500 Begin Route Marina del Rey C  
LA 187 PM  04.440 Marina del Rey Ballona Creek C  
LA 187 PM  08.900 Ballona Creek End Route C  
LA 187 PM R00.000 Begin Route Los Angeles River C Jct 5
         
LA 210 PM R31.640 Los Angeles River Peck Road Lake C 0.36 mile E. of Santa Anita Ave.
LA 210 PM R36.000 Los Angeles River San Gabriel River C  
LA 210 PM R46.330 San Gabriel River Puddingstone Reservoir C 0.11 mile E. of San Dimas Canyon Rd.
LA 210 PM R49.130 Puddingstone Reservoir San Gabriel River C 0.02 mile E. of College
LA 210 PM R50.470 San Gabriel River Santa Ana River C  
LA 210 PM R51.850 Santa Ana River San Gabriel River D Baseline Rd.
LA 210 PM R51.960 San Gabriel River Santa Ana River D  
LA 210 PM R52.150 Santa Ana River End County C  
         
LA 213 PM  00.000 Begin Route JG 7 of Santa Monica Bay C  
LA 213 PM  00.120 JG 7 of Santa Monica Bay Los Angeles Harbor C  
LA 213 PM  04.150 Los Angeles Harbor Machado Lake C  
LA 213 PM  07.740 Machado Lake Dominguez Channel C  
LA 213 PM  07.984 Dominguez Channel End Route C Carson St.
         
LA 405 PM  00.266 Begin County San Gabriel River C Atherton St.
LA 405 PM  00.420* San Gabriel River Los Cerritos Channel and Alamitos Bay B  
LA 405 PM  05.950 Los Cerritos Channel and Alamitos Bay Los Angeles River C  
LA 405 PM  08.700* Los Angeles River Dominguez Channel B  
LA 405 PM  22.470 Dominguez Channel Ballona Creek C  
LA 405 PM  37.130 Ballona Creek Los Angeles River C  
LA 405 PM  48.600 Los Angeles River End Route C  
         
LA 605 PM  00.000 Begin County San Gabriel River C  
LA 605 PM  24.000 San Gabriel River Peck Road Lake D  
LA 605 PM  25.100 Los Angeles River San Gabriel River D  
LA 605 PM  26.000 San Gabriel River End Route C  
         
LA 710 PM  05.000 Begin Route Los Angeles Harbor C  
LA 710 PM  06.390 Los Angeles Harbor Los Angeles River C  
LA 710 PM  32.700 Los Angeles River End Route C  
         
VEN 001 PM  00.000 Begin County JG 1 of Santa Monica Bay C  
VEN 001 PM  00.020 JG 1 of Santa Monica Bay Ventura Coastal Streams C  
VEN 001 PM  07.480 Ventura Coastal Streams Calleguas C  
VEN 001 PM  09.900 Calleguas Revolon Slough C  
VEN 001 PM  10.800 Revolon Slough Calleguas C  
VEN 001 PM  10.920 Calleguas Revolon Slough C  
VEN 001 PM  13.260 Revolon Slough Calleguas C  
VEN 001 PM  14.600 Calleguas Oxnard C  
VEN 001 PM  17.630 Oxnard Channel Islands Harbor C  
VEN 001 PM  19.630 Channel Islands Harbor Santa Clara River C  
VEN 001 PM  21.075 Santa Clara River Route Break C Joining US 101.
VEN 001 PM  21.250 Restart Route Pitas Point C Separating from US-101.
         
VEN 023 PM  00.000 Begin County Malibu Creek C  
VEN 023 PM  03.200 Malibu Creek Route Break into Calleguas C  
VEN 023 PM  03.339 Restart Route from Calleguas Calleguas C  
VEN 023 PM  18.560 Calleguas Santa Clara River C  
VEN 023 PM  24.165 Santa Clara River End Route C  
         
VEN 033 PM  00.000 Begin Route Ventura River Estuary C at Ven 101
VEN 033 PM  04.090 Ventura River Estuary Ventura River C  
VEN 033 PM  04.500 Ventura River Ventura River Estuary C  
VEN 033 PM  05.560 Ventura River Estuary Ventura River C  
VEN 033 PM  25.720 Ventura River Santa Clara River C  
VEN 033 PM  26.190 Santa Clara River Ventura River C  
VEN 033 PM  26.910 Ventura River Santa Clara River C  
VEN 033 PM  42.800 Santa Clara River Santa Maria C  
VEN 033 PM  57.500 Santa Maria End County C  
         
VEN 034 PM  04.295 Begin Route Channel Islands Harbor C  
VEN 034 PM  04.320 Channel Islands Harbor Oxnard C  
VEN 034 PM  06.300 Oxnard Revolon Slough C  
VEN 034 PM  07.300 Revolon Slough Calleguas Creek C  
VEN 034 PM  07.600 Calleguas Creek Revolon Slough C  
VEN 034 PM  11.860 Revolon Slough Calleguas Creek D  
VEN 034 PM  13.170 Calleguas Creek Revolon Slough D  
VEN 034 PM  13.320 Revolon Slough Calleguas Creek D  
VEN 034 PM  17.600 Calleguas Creek End Route C  
         
VEN 101 PM  00.000 Begin County Malibu Creek C  
VEN 101 PM  01.210 Malibu Creek Calleguas Creek C  
VEN 101 PM  14.050 Calleguas Creek Revolon Slough C  
VEN 101 PM  20.080 Revolon Slough Oxnard C  
VEN 101 PM  21.060 Oxnard Santa Clara River C  
VEN 101 PM  25.900 Santa Clara River Buenaventura C  
VEN 101 PM  30.650 Buenaventura Ventura River Estuary C  
VEN 101 PM  31.530 Ventura River Estuary Pitas Point C  
VEN 101 PM  43.530 Pitas Point South Coast C  
VEN 101 PM  43.622 South Coast End County C  
         
VEN 118 PM  00.516 Begin County Santa Clara River C  
VEN 118 PM  02.820 Santa Clara River Revolon Slough C  
VEN 118 PM  09.280 Revolon Slough Calleguas Creek C  
VEN 118 PM  32.600* Calleguas Creek End County B  
         
VEN 126 PM  00.000 Begin Route Buenaventura C  
VEN 126 PM  00.970 Buenaventura Santa Clara River C  
VEN 126 PM  34.637 Santa Clara River End County C  
         
VEN 150 PM  00.000 Begin County South Coast C  
VEN 150 PM  02.530 South Coast Pitas Point C  
VEN 150 PM  05.240 Pitas Point Ventura River C  
VEN 150 PM  25.520 Ventura River Santa Clara River C  
VEN 150 PM  34.400 Santa Clara River End Route C  
Notes:  This report should generally be consistent with the 1:200,000 scale watershed boundary maps also published by GIS Branch via Internet and PDF.  For some Caltrans projects, the listing may be a convenient alternative to those maps for finding associated watersheds.  Neither the maps nor this list are certain, especially where routes pass near watershed edges.  It is derived from various sources, of varying positional accuracy, but mostly EPA and Department of Water Resources watershed mapping, with the HQ Office of GIS postmile service.  Some locations or purposes may require further study of drainage structures.  Consult the glossary below, and contact GIS Branch or Stormwater Branch for more information.
Glossary--
CO/RTE/PM County, Route, and Postmile of estimated crossing of route centerline.
Prefix added where significant.  (e.g. LA-101 spur and 10 spur)
An asterisk * indicates some verification performed.  (see also POS.)
LEAVING The name of the watershed behind (in the direction of decreasing postmiles) this postmile point.
The watersheds are really sub-watersheds defined by differing pollution control regulations.  For example, at one time, we mapped Marina del Rey "watershed" because a TMDL agreement was under study.  Even after such a TMDL agreement is officially accepted, such a small pollution control regulation area may never become part of the published statewide Cal-Water system.  If you ask, we can provide a table showing how our watershed regulation areas fit under those larger watersheds.
ENTERING The name of the watershed regulation area ahead of (in the direction of increasing postmiles) this postmile point.
POS Positional accuracy "letter grade" for this watershed crossing.
"A" = Complete study of drainage structures to delineate a boundary accurate enough for any purpose.  Neither a postmile nor our usual maps could accurately represent such a detailed boundary, so a special map would need to be prepared for each crossing, or a zoomable CADD or GIS map employed.
"B" = Superficial analysis of drain plans and surface topography to delineate watershed limits with better accuracy than statewide GIS sources alone.  Sometimes the analysis was performed by City engineers or consultants, sometimes by Caltrans Hydraulics or GIS staff.  "B" listings are about the same accuracy as a good postmile fix, which generally means +/-100 feet along the centerline.  Still, mapping bigger than our standard 1:200,000 scale will be required to see the detail near these crossing points.
"C"= Simple intersection of TeleAtlas roads with watersheds from DWR and other sources, including digitizing off paper maps.  Little consideration may have been given to subsurface structures.  In at least one case, a sump rendered the "C" mapping incorrect by miles!  However, for low-risk purposes, "C" is probably the only boundary available.
"D"=Same as "C" except that the watershed boundary appears to be meandering along our route, meaning you should consider asking for a "B" accuracy study.
COMMENT To clarify the location or special considerations.