Why the Marsh Behind Franklin Boulevard Keeps Getting Bigger

If you have driven Franklin Boulevard toward the Cosumnes River Preserve any time in the last few years, you may have noticed the wetland footprint keeps expanding. Fields that used to grow row crops are underwater in winter now. Stands of young valley oak stand where there used to be irrigation ditches. Ask most people why, and you get some version of "the Nature Conservancy owns it" or "it's a state park thing." Neither is quite right anymore, and the real answer explains why the marsh keeps growing on a schedule you can actually track.

In mid-July 2026, Sacramento Valley Conservancy and a company called Westervelt Ecological Services announced they had permanently protected a fresh piece of river frontage inside the Preserve: the Johnson Cosumnes Mitigation Bank. It is not a park purchase funded by your property taxes or a nonprofit's donor gala. It is a private restoration project, paid for by something happening nowhere near Galt at all.

The land didn't come from a park fund. It came from a permit somewhere else

Here is the mechanism, in plain terms. When a developer, a utility, or a public agency somewhere in California disturbs a wetland or a stream while building something, state and federal rules often require them to offset that damage. One way to do it is to buy "mitigation credits" from a company that has restored habitat somewhere else. Westervelt is that company here. It buys agricultural land along the Cosumnes, tears out the berms that keep the river fenced in during flood season, and sells the resulting habitat credits to whoever needs to offset a project elsewhere in the region.

Westervelt's own July 13 announcement describes the Johnson Cosumnes site as 217 acres. The Conservancy's release a few days later, on July 17, describes the deal as covering 204 acres of new river frontage inside the more than 51,000-acre Cosumnes River Preserve. The discrepancy is likely a matter of gross acreage versus protected frontage, and either way, this is the same parcel: a stretch of the lower Cosumnes that fills a gap in an otherwise fragmented corridor of protected floodplain.

This isn't a one-off. Westervelt has now completed five restoration projects adjacent to the Preserve, and together with the Conservancy has permanently protected more than 1,350 acres of Cosumnes floodplain, including two earlier projects called Zacharias and McDonald Ranch. If you have watched the marsh grow for a few years running, this is why: it is not a single donation drive winding down. It is a repeatable business model that keeps adding acreage every time a construction project somewhere else in the state needs a wetland offset.

Kelly Hopkins, executive director of Sacramento Valley Conservancy, put the stakes in plainer terms when the deal closed:

"This property is a critical wildlife linkage in the Cosumnes River corridor, and Sacramento Valley Conservancy is thrilled to partner with Westervelt to protect it in perpetuity."

What construction crews are doing to the land this year

The restoration plan for Johnson Cosumnes is not decorative. Crews are lowering or removing sections of the old agricultural berms so the river can reconnect with its historic floodplain during high water. They are cutting a network of channels designed to move fish more freely between the restored floodplain and the main river as conditions change through the season, which matters for keeping juvenile salmon from getting stranded when water levels drop. The project also targets what biologists call thermal refuge: more shade, more natural flow, and better connections to cooler water pockets that fish need to survive a Central Valley summer.

Construction is expected to wrap this fall, with an additional release of mitigation credits following completion. For a Galt resident, the practical translation is that the parts of the Preserve nearest this new parcel will look visibly different by winter than they did last year. Where there was flat pasture, expect standing water, new channels, and the kind of scrubby young growth that draws waterfowl before it draws hikers.

Getting there before the cranes do

None of this changes how you actually visit the Preserve. The Visitor Center is still at 13501 Franklin Blvd, and the core trail system is unchanged even as the acreage around it grows:

• River Walk Trail – a 3.3-mile loop along the river and adjacent meadows, mostly flat, mixing boardwalk and natural surface
• Lost Slough Wetlands Walk – about a mile, crossing Willow Slough and looping past a perennial pond good for spotting turtles
• The boardwalk trail – a quarter-mile, ADA-compliant loop that is especially worth it once sandhill cranes are on the ground
• Second Saturday River Walk Bird Surveys – docent-led monthly surveys, early morning, meeting at the Visitor Center

The trails themselves are open sunrise to sunset, though the Visitor Center building keeps shorter posted hours, generally in the 9 to 5 range. There is no potable water on the trails, so bring your own, and bug spray is not optional near the sloughs in warmer months. Pets are not allowed beyond service animals on leash, and there is no camping, hunting, or bank fishing anywhere inside the core Preserve.

The reason to plan around this fall specifically is timing. Sandhill cranes typically begin arriving in late September, with prime viewing running from October 15 through March 1. That window now overlaps almost exactly with the construction wrap-up on the new Johnson Cosumnes parcel, which means the first crane season after this expansion will show you the freshest version of the corridor before a full year of growth smooths it over.

A pattern worth knowing if you live here

The Preserve started small. The Nature Conservancy's original purchase in 1984 was 85 acres of old-growth riparian forest. Four decades later it has grown past 51,000 acres through a mix of public agencies, a private company selling mitigation credits, and partners including the Bureau of Land Management, Ducks Unlimited, Sacramento County Parks and Open Space, and the California Department of Fish and Wildlife. On a single winter day, observers once tracked 58,000 birds moving through the Preserve in one sitting, a number that gives some sense of why the Pacific Flyway treats this stretch of the Cosumnes as a critical stopover rather than a nice-to-have.

Knowing how the growth actually happens changes what you watch for. Instead of waiting for a headline about a new state park or a donor campaign, the next expansion is more likely to show up quietly, tied to a mitigation filing for a project you will probably never hear about directly. Westervelt has said it intends to keep adding priority parcels along the corridor. If the last decade is any guide, the marsh behind Franklin Boulevard is going to keep getting bigger, on a schedule set by construction permits somewhere else in California rather than by anyone's fundraising calendar.

That is a strange thing to know about your own backyard nature preserve, and it is the kind of detail that does not show up on a trail map. It is also a good excuse to go take a look at what changed before this fall's cranes fill in the rest of the story.

If you are curious about property near the Preserve, on Franklin Boulevard, or anywhere else in Galt, Herald, or Wilton, Roenspie + Johnson knows this corridor well and is always happy to talk through what is happening in the neighborhood. Contact us for a local market consultation whenever the timing is right for you.