I came across this site while out exploring. It’s a field and wetland managed for wildlife habitat. Several paths, perhaps a little over 1/2 mile, have been mowed in the tall grass to allow easy walking around the site to explore, learn, and to watch for wildlife. You can also view the spring which is the headwaters of Curtin Creek.
It can be tricky to reach, since the entrance is at the end of NE 72nd Ave, and 72nd Ave can only be turned onto when going west on NE 78th St.
Curtin Creek Wildlife Habitat 
Curtin Creek Wildlife Habitat 
Curtin Creek Wildlife Habitat
We visited today (4/4/22) but the gate was locked. It was 4;00 p.m. what hours and dsys is this habitat area open to the public?
Sorry, I had missed this question when you posted it some months ago. I believe that at Curtin Springs you can walk the trails at any time (daylight hours), just the parking lot and office are closed outside of regular hours. I have usually parked in the cul-de-sac near the entrance and walked in.
Why is it so hard to find information about this place? This page is the only mention we could find online, except it is shown on Google Maps. All the signage indicates it’s owned and managed by Clark County, but there’s nothing about it on the county website. But maps also show that it’s within the Vancouver city limits. Their website has nothing about it either. Today around 11am the gate was closed so we parked across the street. It’s a pleasant little walk, but you have to tune out the traffic noise and focus on the birds. Does anyone know the story about the house? It looks well maintained but not occupied.
The house is used as an office for maintaining the wildlife habitat.
Here are other items I could find online about the site:
On YouTube: Curtin Springs Wildlife Habitat
In The Columbian: Farmer’s wish for donated land coming to fruition
Clark County Parks Year in Review for 2016 includes some details.