Chapter 3 - Natural Resources - Marine Corps Base Camp Pendleton
Chapter 3 - Natural Resources - Marine Corps Base Camp Pendleton
Chapter 3 - Natural Resources - Marine Corps Base Camp Pendleton
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Integrated <strong>Natural</strong> <strong>Resources</strong> Management Plan [March 2012 - Update]<br />
maintained for each gauging station on or near <strong>Camp</strong> <strong>Pendleton</strong> and presented in Appendix<br />
H. A discontinuous collection of flow data, however, hinders the accuracy of some of these<br />
historical records.<br />
Peak discharges will likely increase in future years due to the effects of expanded<br />
urbanization in the upper watershed. Since the Leedshill-Herkenhoff 1989 study, the <strong>Base</strong><br />
reexamined these 100-year flow computations, particularly during the design of the Levee<br />
and Bridge project that was constructed from 1998 to 2001 to protect MCAS <strong>Camp</strong><br />
<strong>Pendleton</strong> and the 22-Area Industrial Complex. The 100-year design was initially<br />
computed to be 57,000 cfs but a severe storm in 1998 caused a revaluation of the river’s<br />
hydrologic characteristics resulting in an increase in the estimation of the 100-year flow to<br />
64,000 cfs.<br />
During the summer months and periods of extreme drought, the frequency of extremely<br />
low-flows within unregulated streams is particularly high throughout <strong>Camp</strong> <strong>Pendleton</strong>. It is<br />
not unusual for the San Mateo, San Onofre, and Los Flores Creeks to be dry from July<br />
through October. Historical data shows that the Santa Margarita River fails to flow to the<br />
ocean approximately 25% of the time (Leedshill & Herkenhoff 1989).<br />
3.1.4.3. Floodplains and Surface Waters<br />
<strong>Camp</strong> <strong>Pendleton</strong> recently completed several hydrologic and hydraulic studies of the major<br />
stream systems on <strong>Base</strong>. The Santa Margarita River study was completed in July 2000 and<br />
the Las Flores, Horno, Aliso, San Mateo and San Onofre Creek studies were completed<br />
during 2004. These studies determined the flow rate that would predict 100-year flood<br />
conditions for each of the major streams on <strong>Base</strong> (Table 3-3).<br />
TABLE 3-3. FLOW RATE PREDICTING 100-YEAR FLOOD CONDITIONS FOR<br />
MAJOR DRAINAGES ON MCBCP<br />
Drainage<br />
100-year flow<br />
(cfs)<br />
Author/Date<br />
Santa<br />
WEST Consultants<br />
64,000<br />
Margarita<br />
2000<br />
Aliso 2,659<br />
WEST Consultants<br />
2004<br />
Las Flores 7,803<br />
WEST Consultants<br />
2004<br />
Horno 1,404<br />
WEST Consultants<br />
2004<br />
San Onofre 14,158 URS 2004<br />
San Mateo 56,697 URS 2004<br />
<strong>Chapter</strong> 3 – <strong>Natural</strong> <strong>Resources</strong> 3-7