I'd like to fly to Borrego Valley Airport (L08) and it's inside California's Anza-Borrego Desert State Park. How does this work, given that I'm supposed to say at least 2000 feet AGL when flying over a state park? Am I allowed to descend below 2000 feet AGL only for takeoff and landing at the airport, or can I be below 2000 feet AGL at other times when flying over the state park?
You should minimize your time less than 2000 ft AGL while safely operating the aircraft to arrive at Borrego Valley (L08). I would interpret the rule to mean I will only descend below 2000 ft AGL when it is required for my safe descent to arrive at a normal pattern altitude in a safe position to land the aircraft.
Here's an excerpt from FAA Advisory Circular 91-36D titled VISUAL FLIGHT RULES (VFR) FLIGHT NEAR NOISE-SENSITIVE AREAS that explains this rule:
b. Pilots operating noise producing aircraft (fixed-wing, rotary-wing and hot air balloons) over noise sensitive areas should make every effort to fly not less than 2,000 feet above ground level (AGL), weather permitting. For the purpose of this AC, the ground level of noise-sensitive areas is defined to include the highest terrain within 2,000 feet AGL laterally of the route of flight, or the uppermost rim of a canyon or valley. The intent of the 2,000 feet AGL recommendation is to reduce potential interference with wildlife and complaints of noise disturbances caused by low flying aircraft over noise-sensitive areas.
c. Departure from or arrival to an airport, climb after take-off, and descent for landing should be made so as to avoid prolonged flight at low altitudes near noise-sensitive areas.
d. This advisory does not apply where it would conflict with Federal Aviation Regulations, air traffic control clearances or instructions, or where an altitude of less than 2,000 feet AGL is considered necessary by a pilot to operate safely.
Having never flown into this airport before, I would study the sectionals and charts very carefully. The state park is one concern. There are specific notes on the sectional requesting aircraft to stay above 2000 feet. There are also restricted areas, military training areas, laser illumination areas, etc. all around the airport. Not to mention the rising terrain and obstacles as high as 7100 feet around an airport with a 522-foot field elevation and a 10,000-foot Minimum Sector Altitude. Then, the airport having to have a specific obstacle departure procedure is a big red flag for me.
If it were me flying into this airport, I would request flight following to the RNAV (GPS) RWY 26 IAP all the way in to the traffic pattern. Then, I would land straight in or circle to runway 8. The minimums are probably a full 1200 feet above the field elevation for a reason. Remember to circle South of the airfield (right traffic pattern for runway 8). And, do not overfly the area Northwest of the field nor the elementary school 1 nautical mile West of the field. This is from a quick glance of the charts and chart supplement.