Coastal San Luis Resource Conservation District

The Los Osos Creek Wetland Reserve

 

This 144 acre site is located on Los Osos Creek, just upstream of the Morro Bay estuary.  The site is owned by George Martines, a private landowner.  The USDA Natural Resources Conservation Service (NRCS) and the Coastal San Luis Resource Conservation District (CSLRCD) have purchased permanent wetland reserve easements on the property.  The State Coastal Conservancy (SCC) provided funding for the CSLRCD easement.

The easements were acquired in order to return 111 acres to flood plain and riparian habitat and serve as a sediment deposition area, trapping sediment before it could enter Morro Bay.  Thirty-three acres are permanently protected in an agricultural easement.  As this is still private property, there is no public access to the site.

Project Background:
Morro Bay is the most significant estuary along the central coast of California.  It provides significant economic, recreational, environmental and esthetic values.  The most significant problem facing the Bay is accelerated sedimentation.  Los Osos Creek drains into Morro Bay and delivers a significant share of the sediment to the Bay.  Recent studies funded by the SCC and coordinated by the CSLRCD documented the impacts of sediment on the Bay, resulting in the Morro Bay Watershed Enhancement Plan to reduce watershed sedimentation.  Several elements of the plan have already been implemented.

One key component of the plan is to provide a sediment trap on Los Osos Creek near its confluence with Morro Bay.  To accomplish this, the wetland reserve easements were purchased in 1995. Historically, the site was a freshwater wetland and riparian forest.  In the twentieth century the site was converted to agricultural use.  The creek bed was moved and levees were constructed along the creek to control flooding.  It was farmed continuously until 1995.  Since 1995 the site has been allowed to revert to wetland.  The floods of 1995 did most of the work by rupturing the levees and seeding the area with millions of willow trees.

Today, the site is functioning as a sediment trap and is outstanding wildlife habitat.  Mature steelhead trout have been observed in the creek.  Large bucks roam the willows.  Birds and waterfowl are constantly in abundance.  In the winter of 1997-98, it was estimated that more than 70,000 cubic yards of sediment were accumulated on the site.

Recent News:
The CSLRCD is beginning work on a Management Plan for the Los Osos Creek Wetland Reserve.  The CSLRCD will be releasing an RFP to consultants in the near future for developing the management plan. ... A steelhead trout migration barrier project was completed in November 1998.  A massive log jam, sediment and debris was removed from the channel of Los Osos Creek in order to insure that steelhead trout could migrate through the site to their spawning grounds in Clark Valley.


Los Osos Wetland map