Martha McLean – Anza Narrows, Regional park by Santa Ana River in Riverside, California.

Martha McLean – Anza Narrows is a 40-acre (0.16 km²) regional park on a shaded bluff above the Santa Ana River in Riverside, California. Its landscape mixes shaded picnic areas with open turf and ends at bluffs that drop to the river. The park has an 18-hole disc golf course, hiking, bicycle and equestrian trails, and reservable group picnic sites.

The grounds mark where Juan Bautista de Anza's expeditions crossed the Santa Ana River in 1774 and 1776, establishing the first European passage through Riverside. This crossing became a key route for early settlement and development in the region.

The grounds connect visitors to the Juan Bautista de Anza National Historic Trail extending across Southern California through an on-site commemorative marker. The location reflects the early importance of this passage for European exploration in the region.

The park sits on a bluff above the Santa Ana River, with picnic areas and open turf ending at the bluffs that drop to the water. Trails for hiking, bicycles and horses cross the grounds, and an 18-hole disc golf course occupies part of the site. Group picnicking is available with reservations made through the City of Riverside.

The park's name honours Martha McLean, who with her friend Ruth Anderson campaigned in the 1960s against the US Army Corps of Engineers' plan to channelise the Santa Ana River. The river here keeps a natural course instead of a concrete channel, and the park sits on a shady bluff above it.