The 93-acre expansion area at Mile Square Regional Park has been closed since September 23, 2024. OC Parks' Phase 2 notice lists what is being built behind the fence: an amphitheater, a Great Meadow, a Children's Adventure Play Area, a multi-use field, a main vehicle road, parking and a restroom building. OC Parks expects to finish by spring 2027.
Those 93 acres used to be the Mile Square Golf Course. The Orange County Register covered the decision in July 2021 under a headline about the park losing 18 holes of golf and gaining 93 acres of recreation space. Some of what the county is building now was originally scheduled for later. The pieces under construction are the ones meant for crowds: a lawn sized for events, terraced seating facing it, and a play area big enough to draw families from outside the neighborhood. When they're done, they also let the City of Fountain Valley grow its own side of the park.
What the county is building, by the numbers
The county's Final Environmental Impact Report, dated July 2021, has the most detail on what these features will look like.
| Feature | What the 2021 plan describes |
|---|---|
| Great Meadow | 8 acres at the center of the former golf course parcel |
| Amphitheater | Terraced seating next to the meadow, designed for 2,000 people |
| Children's Adventure Play Area | 2 acres of open-ended, nature-oriented play, with areas for several age groups |
| Multi-use turf field | Sports, plus overflow parking, event spillover and special programming |
| Vehicle access | A new entrance at Heil Avenue and Euclid Street, with a 30-foot internal road tying into existing park roads near Edinger Avenue and Euclid Street |
A 2,000-seat amphitheater is a large venue for a park that has mostly hosted ball games, picnics and fishing. Mile Square totals 607 acres. It has two 18-hole golf courses on its western edge, three soccer fields, three baseball and three softball diamonds, an archery range, a nature area and two fishing lakes. None of that includes a dedicated place for concerts or large gatherings. The plan is also built around events. Even the multi-use field is meant to take overflow parking and spillover crowds when the meadow and amphitheater are in use.
The meadow moved up a phase
The 2021 plan split the expansion into phases and gave each one its own work. The early phases looked like this:
- Phase 1: a modified pond, new circulation trails, a permanent 20-foot-wide perimeter trail with security lighting, tree planting and hydroseeding, picnic tables in the northeast corner, and temporary restrooms in the southwest corner.
- Phase 2A and 2B: maintenance yard changes, pond and habitat work, the main road, two parking lots, a restroom building, the Heil Avenue entry, stormwater channel improvements, new pathways and a relocated ranger station.
- Phase 3: the multi-use turf field, a historic promenade with a tree walkway, the Great Meadow, another restroom and two more parking lots.
- Phase 4: a Civic Plaza and Visitor Center, more trees, one more pond modification and one more parking lot.
The Phase 2 under construction now includes the Great Meadow and the multi-use field, which the 2021 plan had put in Phase 3. It also includes the amphitheater and the Children's Adventure Play Area. The plan expected this kind of change. It says the order of phases "may be altered based on changing needs, available grants, and alternative financing opportunities." In practice, that means the meadow and the amphitheater will arrive with this phase. The plan had them as the second wave of work.
The 2023 trail is behind the same fence
Phase 1 construction started in March 2022. OC Parks' expansion page records it as complete and open to the public in November 2023. The county's Phase 1 plan sheet shows picnic tables, pedestrian paths, a restroom, a lighted path for pedestrians and emergency or maintenance vehicles, and the lakes.
Ten months later, the fence closed off all of it. The Mile Square park page says the entire 93-acre expansion area stays closed until Phase 2 is finished. The lighted perimeter trail and the picnic tables in the northeast corner are inside the construction zone. When the expansion reopens, the lighted trail will come back along with the new meadow, amphitheater and play area.
Fountain Valley's side of the park is waiting
The 607 acres include land the county leases to the City of Fountain Valley along Brookhurst Street. The city has built that land into the Fountain Valley Recreation Center & Sports Park, with a community center, lighted ball diamonds, basketball courts, play areas and a tennis complex.
In early 2025, the Orange County Board of Supervisors approved a new 50-year lease. The Orange County Register reported on March 7, 2025, that the lease adds about 14 acres and brings the city's share to about 92 acres. The added land extends from the ball fields that reach farthest into the park. The Register reported that the city gets that land once the county finishes converting the golf course and the city updates its parks master plan. The agreement estimated 18 to 24 months.
The Register also quoted the city's Community Services Director, Rob Frizzelle, on what residents have asked for:
"We have frequently heard from our residents the need for independent active recreational needs such as dog parks, expansion of the fitness trails, more pickleball — there is always a need for more pickleball — as well as reservable event venues and sports fields."
That is a list of resident requests, not a design. The Register ties the handover to the city's parks master plan update. In the same Register article, First District Supervisor Janet Nguyen said, "This park is very utilized throughout the year, whether it's the county side or the city side." Ted Bui, Fountain Valley's mayor at the time, said the added land means "a lot more green space, a lot more activities that our residents and surrounding cities will be able to enjoy."
Both sides of the park are moving toward more use at once. The county is building gathering space in the middle of the park, and the city is lined up to add recreation acreage beside it. The city's part can't start until the county's is finished.
What's open at Mile Square this month
The rest of the park is open while the work continues. Fall and winter hours are 7 a.m. to 6 p.m. The Nature Area is open daily from 7 a.m. to 3 p.m. Parking costs $3 per vehicle on weekdays and $5 on weekends, and more on some holidays and event days. Freedom Hall has free table tennis and badminton on Saturdays and Sundays from 8 a.m. to 4 p.m., first come, first served.
The OC Parks calendar for 16801 Euclid St. still has these November programs:
- Thursday, November 19: Introduction to Archery for Adults, at the park's archery range.
- Saturday, November 21: Makers Square: Paint Your Own Wood Coaster.
- Saturday, November 21: Jr. Ranger Adventure: Mile Square Regional Park, which OC Parks lists under "Multiple Locations."
The two fishing lakes and the bike and paddle boat rentals are in the original park, outside the fence. On a weekend walk you can circle the lakes and look across the fence at the old fairways where the 8-acre meadow and the 2,000-seat amphitheater are planned. OC Parks anticipates completion by spring 2027.
When the expansion opens, it will add a large event venue and a new front entrance at Heil and Euclid to the streets east of the park. If you live near Mile Square and are thinking about selling before or after that, 1% Listing Broker can give you a free 1% home valuation. We'll show you what your home could sell for and how much more you'd keep with a flat 1% listing fee.
