Cal. Gov. Code § 23130
The boundaries of Orange County are as follows:
Beginning at the northwest corner of San Diego County at a point in the Pacific Ocean opposite San Mateo point; thence northerly along the San Diego County line to the southerly line of the Rancho Mission Viejo as shown on the survey on file in book 8, pages 34 through 46 inclusive of Records of Survey in the office of the County Recorder of Orange County;
Thence, easterly and northeasterly to an angle point therein, said point being Rancho Mission Viejo Corner No. 7, as shown on said Record of Survey; thence northerly 12,693.95 feet along the northwestern boundary of San Diego County to the southwest corner of Section 33, T. 7 S., R. 6 W., said point being also the most southwest corner of Riverside County; thence northerly 1,324.46 feet along the western boundary of said Riverside County to the southwesterly corner of Government Lot 3, Fractional Section 33, T. 7 S., R. 6 W., S.B.M., as shown on that survey on file in book 122, pages 17 and 18 of Records of Survey in the office of the County Recorder of Orange County;
Thence leaving said western boundary south 89°25'11" east, 2,042.68 feet to the southeast corner of the NE. 1/4 of the SE. 1/4 of said Section 33; thence north 01°00'50" east, 1,320.33 feet to the northeast corner of the NE. 1/4 of the SE. 1/4 of said Section 33; thence north 00°27'14" east, 2,647.46 feet to the northeast corner of said Section 33; thence along the north line of said section north 89°16'14" west, 2,086.39 feet to the northwest corner of Government Lot 1 of said section, being a point on the existing western boundary of said Riverside County;
Thence along said boundary of Riverside County northerly, northeasterly, northwesterly, westerly, northerly, westerly and northwesterly to a point on the south line of Section 36, T. 3 S., R. 8 W., as shown on that survey on file in book 131, pages 24 and 25 of Records of Survey in the office of the Orange County Recorder, said point lying distant therein north 89°05'38" west 151.58 feet from the southeast corner of said Section 36;
Thence leaving said existing boundary of Riverside County and along said south line north 89°05'38" west, 2,484.00 feet; thence continuing along said south line, north 89°07'27" west, 818.46 feet to the easterly line of the Rancho Lomas de Santiago; thence along said easterly line north 02°53'27" west, 3,273.18 feet to a point on a nontangent curve, concave to the northwest and having a radius of 1,550.00 feet, a radial from said point bears north 14°05'30" west; thence easterly, leaving said east line, along said curve through a central angle of 15°01'17" and arc length of 406.35 feet; thence nontangent to said curve, south 84°32'29" east, 155.61 feet; thence north 65°40'06" east, 75.15 feet; thence north 48°16'56" east, 150.70 feet; thence north 68°49'57" east, 35.37 feet to said existing boundary of Riverside County;
Thence northwesterly along the said boundary to the corner common to Riverside, San Bernardino, and Orange Counties; thence northwesterly along the southwest boundary of San Bernardino County to the point of intersection of said boundary with the southerly line of T. 2 S., R. 9 W., being also the corner common to San Bernardino and Los Angeles Counties; thence westerly along the township line between T. 2 and 3 S., to the northeast corner of Annexation 69-1 (Ryness-Smith No. 2) to the City of Brea, said point also being the southeast corner of Tract No. 46685, per map filed in Book 1209, pages 56 and 57, of Maps, in the office of the Recorder of the County of Los Angeles, being distant north 89°00'53" west, 1670.40 feet from the northeast corner of Section 3, Township 3 South, Range 10 West; thence, leaving the Township line between T. 2 and 3 S., along the boundary line of said Tract No. 46685, the following courses: north 13°53'07" east, along the easterly line of said Tract, 100.12 feet to the northeast corner thereof; thence, north 76°01'25" west, along the northeasterly line of said Tract, 1018.58 feet to the easterly terminus of that course shown as "north 86°32'58" west, 163.32 feet" on said Tract; thence, north 85°34'56" west, along the northerly line of said Tract, 163.25 feet to the northwest corner thereof; thence, south 00°57'29" west, along the most westerly line of said Tract, 47.01 feet, to the northeasterly boundary line of Tract No. 25335, per map filed in Book 775, pages 35 and 36, of Maps, in the office of the Recorder of the County of Los Angeles, said point being north 76°00'59" west, along said northeasterly line 10.26 feet, from the northeast corner of said Tract; thence along the boundary of said Tract No. 25335, the following courses: north 76°00'59" west, along said northeasterly line of said Tract, 1224.52 feet to the northwest corner thereof; thence south 00°52'39" west, along the westerly line of said Tract, 564.75 feet to the southwest corner of said Tract, being a point of intersection with the Township line between T. 2 and 3 S., distant south 89°00'53" east, 1449.86 feet from the northwest corner of said Section 3, Township 3 South, Range 10 West; thence, leaving said boundary of Tract No. 25335, westerly along the Township line between T. 2 and 3 S., to the corner common to T. 2 and 3 S., R. 10 and 11 W.; thence southerly along the range line between R. 10 and 11 W., to the southeast corner of Section 13, T. 3 S., R. 11 W., in the Rancho Los Coyotes; thence in a general southwesterly direction along section lines, quarter section lines and quarter quarter section lines in the Rancho Los Coyotes, as follows: westerly along the section line to the quarter corner on the south line of said Section 13; thence southerly along the quarter section line to the center of Section 24, T. 3 S., R. 11 W.; thence westerly along the quarter section line to the quarter corner on the west line of said Section 24; thence southerly along the section line to the southwest corner of said Section 24; thence westerly along the section line to the quarter corner on the north line of Section 26, T. 3 S., R. 11 W.; thence southerly along the quarter section line to the center of said Section 26;
Thence westerly along the quarter section line to the quarter corner on the west line of said Section 26; thence southerly along the section line to the southwest corner of said Section 26; thence westerly along the section line to the northeast corner of Section 33, T. 3 S., R. 11 W.; thence southerly along the section line to the quarter corner on the east line of said Section 33; thence westerly along the quarter section line to the center of said Section 33; thence southerly along the quarter section line to the northeast corner of the SE. 1/4 of the SW. 1/4 of said Section 33; thence westerly along the quarter quarter section line to the center of the SW. 1/4 of said Section 33; thence southerly along the quarter quarter section line to the south line of said Section 33; thence westerly along the township line between T. 3 and 4 S., to the northeast corner of Section 5, T. 4 S., R. 11 W.; thence southerly along the section line to the northeast corner of the SE. 1/4 of said Section 5; thence westerly along the quarter section line to the northwest corner of the NE. 1/4 of the SE. 1/4 of said Section 5; thence southerly along the quarter quarter section line to the center of the SE. 1/4 of said Section 5; thence westerly along the quarter quarter section line to the westerly line of the SE. 1/4 of said Section 5; thence southerly along the quarter section line to the quarter corner on the south line of said Section 5; thence westerly along the section line to the northeast corner of the NW. 1/4 of the NW. 1/4 of Section 8, T. 4 S., R. 11 W.;
Thence southerly along the quarter quarter section lines to the northeast corner of the SW. 1/4 of the SW. 1/4 of said Section 8; thence southwesterly in a straight line to a point on the south line of the Moody Creek Channel as shown on that survey on file in book 120, page 5 of Records of Survey in the office of the Recorder of Orange County, said point being on a nontangent curve, concave southeasterly and having a radius of 950.00 feet, a radial from said point bears south 03°41'24" east; thence westerly along said south line and said curve through a central angle of 26°34'39" and an arc length of 440.67 feet to its point of intersection with the east line of the Coyote Creek Channel, said point being on a nontangent curve concave northwesterly and having a radius of 5,200.00 feet, a radial from said point bears north 75°11'46" west; thence southwesterly along said easterly line and said curve through a central angle of 03°10'38" and an arc length of 288.36 feet; thence continuing along said easterly line, tangent to said curve, south 17°58'52" west, 132.27 feet to a point on the existing boundary of Los Angeles County; thence southwesterly along said boundary in a straight line to the southwest corner of Section 8, T. 4 S., R. 11 W. said corner also being Los Angeles/Orange County Corner No. 11 as shown on Los Angeles County Surveyor's Map No. 8175 on file in the office of the Surveyor of the County of Los Angeles;
Thence south 00°11'50" east, along the section line to a point on the boundary line between Rancho Los Coyotes and Rancho Los Alamitos, said point also being Los Angeles/Orange County Corner No. 10;
Thence south 59°07'40" west, a distance of 3,391.48 feet to Los Angeles/Orange County Corner No. 9;
Thence south 39°48'20" west, a distance of 5,650.97 feet to Los Angeles/Orange County Corner No. 8;
Thence south 11°36'55" west, a distance of 2,241.41 feet to Los Angeles/Orange County Corner No. 7;
Thence south 27°55'55" west, a distance of 8,375.40 feet to Los Angeles/Orange County Corner No. 6;
Thence south 31°22'50" east, a distance of 1,296.21 feet to Los Angeles/Orange County Corner No. 5;
Thence south 27°12'00" east, a distance of 2,106.10 feet to Los Angeles/Orange County Corner No. 4;
Thence south 16°46'45" east, a distance of 1,444.82 feet to Los Angeles/Orange County Corner No. 3;
Thence south 2°48'35" east, a distance of 2,207.94 feet to Los Angeles/Orange County Corner No. 2;
Thence south 57°10'40" west, a distance of 8,238.78 feet to Los Angeles/Orange County Corner No. 1;
Thence south 33°00'00" west, a distance of 622.43 feet to a point on the northeasterly line of block 59, Alamitos Bay tract, as shown on the map recorded in map book 5, page 137, on file in the office of the Recorder of the County of Los Angeles, distant thereon south 57°50'45" east, a distance of 428.91 feet from the most northerly corner of said block 59; thence continuing south 33°00'00" west, a distance of three miles, more or less to the southwesterly boundary line of the State of California (the boundary line between Los Angeles and Orange hereinabove described and established being shown on said county surveyor's map No. 8175; and likewise on map No. 300 on file in the office of the Surveyor of Orange County); thence southeasterly along the state line to the point of beginning.
Ca. Gov. Code § 23130