The road to Cavanaugh Pond Natural Area is restricted to workers only. Sophia and I walked in to see the pond and river. 
I was touring a mobile home for sale for my job (project is a mobiel home park south of the airport, there are several people needing to relocate). And as I was leaving I noticed the road to Cavanaugh Pond. I remember touring this area before, when I trained and volunteered as a Cedar River Naturalist in 2003. It had been raining for a few days, and I had Sophia in the car with me - it was only sprinkling at the time so we stopped to go for a walk!
More pictures below...
More about Cavanaugh Pond
(Courtesy of http://dnr.metrokc.gov/wlr/lands/natural/cavanaugh-pond.htmCavanaugh Pond Natural Area is approximately 44 acres in size and consists of four parcels. The site is located on the left bank of the mainstem Cedar River, between River Mile (RM) 5.5 to 7.0. The western boundary of the site is located at approximately 1/4 mile east of Renton’s city limits. The Natural Area is adjacent to the Cedar River Trail and to State Route 169, Renton-Maple Valley Road. Three of the parcels were acquired in 1976; the fourth parcel was purchased in 1990.
The easternmost parcel of the Natural Area includes 14-acre Cavanaugh Pond, the only Class 1 wetland on the Cedar River valley floor. The wetland supports open water, forested, scrub-shrub, and emergent habitats. The dominant vegetation at the site is typical red alder and black cottonwood riparian forest, with dense understory vegetation. The eastern parcel containing Cavanaugh Pond wetland has more open vegetation along an old roadbed to the north and west side of the pond, where ongoing restoration work is directed at controlling invasive species.
Cavanaugh Pond Natural Area supports a variety of habitats from riparian forest to a structurally complex wetland, which provide diverse habitat for fish and wildlife.
Cavanaugh Pond is noted for its populations of spawning sockeye salmon. The mainstem Cedar River supports coho salmon, chinook salmon, sockeye salmon, coastal cutthroat trout, and winter steelhead.
The eastern parcel of Cavanaugh Pond Natural Area supports regular use by local foot traffic from the Cedar River Trail and by other local residents. Use is primarily for walking and nature observation, concentrated on the levee road and the area around Cavanaugh Pond. The site is used by public agency staff and volunteers for educational activities in the fall in association with Cedar River salmon educational programs. The Washington Department of Fish and Wildlife (WDFW) annually install a temporary weir at the site to collect adult sockeye for hatchery production during the fall.
The primary access to the site is on the easternmost parcel of land: 174th Avenue SE provides direct pedestrian access off of SR 169 and the adjacent Cedar River Trail. From the 174th Avenue entrance, a roadbed provides the main trail into the property. The road extends along the top of the river revetment to the western edge of the pond at the Cedar River. Other informal trails may exist at the site, but there is little to no access to the western parts of the property due to dense vegetation and occasional wetlands along the Cedar River Trail.
There is no authorized parking at the site; parking on the east edge of the site is owned by the Riverbend Mobile Home Park and parking for Natural Area use is not allowed (except under special arrangement during fall salmon education events).