Aptos Creek Is Raising More Young Steelhead in the Forest Than at the Beach

On the morning of September 29, 2025, a fisheries crew stood under the Rio del Mar walk bridge and measured the water of Aptos Lagoon. It was 18.7°C, fresh from surface to bottom, and 1.25 meters deep in the channel. A sand berm had built up at the end of the rock jetty, so even high tide could no longer push saltwater in. Over two days of sampling, the crew estimated 85 juvenile steelhead in the whole lagoon.

That number comes from the county's 2025 Santa Cruz Mountains steelhead monitoring report, prepared by D.W. Alley & Associates and released in April 2026. Read on its own, it looks like a creek in trouble. The same report also follows the creek up into the hills, and up there the figures have been rising for years. The part of Aptos Creek most of us walk past is its weakest stretch. The creek is recovering upstream, and the logs crews dropped into it inside the Forest of Nisene Marks in 2025 are a bet on that upstream recovery.

Upstream, four straight years of gains

Each fall the monitoring crew samples four sites in the Aptos watershed: a lower and an upper site on Aptos Creek, and a lower and an upper site on Valencia Creek. Averaged together, the density of juvenile steelhead has risen every year since 2021.

Fall 2025 brought the four-site trend close to its multi-year average. Yearlings and older fish averaged 6.3 per 100 feet, compared with a long-term average of 5.8. The report flags that with only four sites, the change from 2024 to 2025 is not statistically significant. The five-year direction still holds.

The averages also hide a split. Total and young-of-year densities came in "much below average" at the lower Aptos and lower Valencia sites, and above average at both upper sites. The young fish that hatched in 2025 were found at the upper sites, which means adult steelhead returning from the ocean in the 2025 rains got far enough upstream to spawn there.

What one pile of wood already showed

Between the lower and upper Aptos Creek sites sits a cluster of wood that the monitoring team first examined in 2022. In 2021 the crew found no young-of-year steelhead at the upper site. From 2023 through 2025 they found more there than in 2022, and the report credits the multiple bankfull storm flows of the previous rainy season with letting adult fish get past that wood. In a big enough storm, wood in the creek doesn't keep fish out of the upper reaches, and the upper reaches are where young fish are doing well.

That's the reasoning behind the work State Parks and the Resource Conservation District of Santa Cruz County began on September 23, 2025. Crews placed felled trees and logs along roughly 1.5 miles of Aptos Creek inside the Forest of Nisene Marks. Lookout Santa Cruz reported the start of the project that week. It said the wood is meant to create the twists, turns, pools and riffles salmon rely on, and to trap sediment and reconnect the creek to its floodplain. The State Parks project page puts it more plainly:

"A 'messy' stream is often a healthy one."

The method was "chop and drop," according to a Fall 2026 Cal Fly Fisher column that the RCD included in its October board materials. The same column describes how fallen trees slow the current, which lets gravel settle into spawning beds and gives juvenile fish cover.

The timing matters for reading the numbers above. The crew sampled on September 29 and October 6, 2025, the same weeks crews were working in the creek. The juveniles counted that fall came from spawning in the 2025 rains or earlier, and the 2024 to 2025 gain was already in place before the new wood went in. Last winter was the first spawning season with the logs in the creek.

Down at the beach, the trouble is sand

Wood helps upstream. The lower creek has a different problem. The report says the one February 2025 storm that likely topped bankfull may have reduced egg survival through redd scour or burial in sand, "especially in lower Aptos and all of sandy Valencia Creek." In some wetter years, egg survival in lower Aptos Creek may be much lower because of sedimentation. Some of the lower creek also improved in 2025, with deeper pools, less fine sediment and more escape cover in lower Aptos Reach 3. Fewer fish turned up there anyway.

The lagoon estimate of 85 compares with an 11-year average of 235 and an estimate of 312 in 2024. Soquel Lagoon, a few miles up the coast, held an estimated 2,309 juvenile steelhead the same fall, well above its own average of 1,534. The fish the crew did catch at Rio del Mar were larger than in 2024, which the report suggests may reflect less competition.

Under all of this is a sobering line. The report says the number of adult steelhead returning to the Aptos watershed has likely declined to the point where, in some years, juveniles come nowhere near filling the available rearing habitat, even in dry years. The upper creek has room for more fish. What it needs is more adults reaching it, and the logs are meant to help the ones that do get there.

Walking the creek while the trails are closed

The irony for anyone who loves this forest is that the stretch where the creek is doing best is also the hardest to reach right now. The State Parks page for the Forest of Nisene Marks lists these as closed until further notice because of storm damage and erosion:

• Aptos Creek Trail
• West Ridge Trail Camp
• The trail to Five Finger Falls, closed at the Big Slide Trail and Aptos Creek Trail junction

Aptos Creek Road is down to a single lane in places, walkers share it with cars, and no parking is allowed on the road. Day use is $8 per vehicle.

The closure notice carries no date, so check the park page the morning you go. Several routes in the park's hiking guide don't appear on the closure list. These include Aptos Rancho Trail to George's Picnic Area, Loma Prieta Grade from the Porter Picnic Area toward the Hoffman's site, and the Old Growth Loop past the Pourroy Picnic Area and its grove of old-growth redwoods. That grove was protected in private ownership and added to the park in recent years.

Lower down, two public places put you beside the creek itself. Aptos Village County Park, at 100 Aptos Creek Road, lists creek access among its features. At Rio del Mar State Beach, the walk bridge stands over the same lagoon the crew sampled.

Look from the bank rather than wading in. County Environmental Health keeps a permanent water-quality posting for Aptos Creek at Rio del Mar Beach, most recently updated October 20, 2026, and advises staying out of creeks and lagoons during and after rain.

What the winter rains decide

Steelhead are not the only fish with a stake in Aptos Creek. Across California's coast, the California Department of Fish and Wildlife describes coho moving upstream roughly from mid-November to mid-January, after heavy rain breaks open the sandbars at creek mouths. CDFW includes naturally spawned coho from Aptos Creek in the endangered Central California Coast population. For steelhead, the county report ties the 2025 spawn at the upper sites to that year's winter storm flows, which likely gave adults enough access to reach them. This season's rains will decide how many get past the new wood.

For anyone who wants to help the trails that lead to that forest, Advocates for the Forest of Nisene Marks holds trail days on the third Sunday of each month, weather permitting, with no session in December. The next one is Sunday, November 15, 2026, at 9:30 a.m., followed by January 17, 2027. State Parks says the Nisene Marks Volunteer Trail Crew meets at the entrance kiosk.

After more than thirty years of living near Pleasure Point, I find that the details that matter most along Aptos Creek are often ones the guidebooks leave out. If you'd like to talk about Aptos, the creek, or the corners of mid-county you know best, Caroll Basile is always glad to have that conversation, and to offer a free home valuation whenever the timing is right for you.