ForestWatch and SLO Coastkeeper File Lawsuit to Restore Endangered Steelhead in Sisquoc River

Upper Sisquoc River in the spring.

Today, Los Padres ForestWatch and San Luis Obispo Coastkeeper filed a lawsuit in Superior Court seeking water releases from Twitchell Dam to prevent the extinction of Southern California steelhead in the Santa Maria River system. The legal action aims to ensure that steelhead are left with enough water to swim upstream to historic spawning grounds in the Sisquoc River, deep in the Los Padres National Forest. Click here for our Frequently Asked Questions.

For more than 100 years, California law has required dam operators to release sufficient water to keep fish stocks in good condition. Yet since its construction in the 1950s, the Santa Maria Valley Water Conservation District has managed Twitchell Dam to prevent flows from the Santa Maria River to the ocean, severely limiting migration, and stranding endangered steelhead in a drying channel.

Steelhead were plentiful in the Upper Sisquoc River in 1916, when streamflows were unaltered.

Seventy years ago, the Santa Maria River had the second-largest steelhead run in Santa Barbara County. By some estimates as many as ten thousand fish traveled up the watershed in wet years, with the Sisquoc River in the Los Padres National Forest being the most important spawning tributary within the stream network.

However, several large dams have since blocked historic steelhead runs along the Pacific Coast. Now, steelhead are one of the most endangered fish species in the United States. This unique form of rainbow trout that spawns in coastal streams before migrating to the Pacific Ocean to mature is a keystone species for our region and an indicator of the health of our local waterways.

Twitchell Dam on the Cuyama River – the northern tributary to the Santa Maria River – has been identified as a major obstacle to steelhead passage, but not in the conventional sense. Steelhead have never migrated into the Cuyama in significant numbers. Instead, steelhead migrate to and from spawning grounds in the southern tributary to the Santa Maria River – the Sisquoc River. Rather than physically blocking fish passage, it is the operation of Twitchell Dam, limiting the timing and quantity of flow in the mainstream of the Santa Maria River, that prevents juvenile steelhead from reaching the Pacific, and mature ocean-dwelling steelhead from returning to their natal spawning habitat in the upper Sisquoc River.

The three major rivers involved shown in blue, with their line thickness proportional to streamflow (thicker line = higher streamflow). Note that streamflow in the Cuyama River drops dramatically downstream of Twitchell Dam, subsequently lowering the amount of water in the Santa Maria River.

In 2007, the California Coastkeeper Alliance sued to compel state officials to initiate stream flow studies as required by law. The flow study for the Santa Maria River system was launched in 2010, and the resulting 2013 report by Stillwater Sciences recommended an improved flow regime at Twitchell Dam, yet the water district has failed to implement the recommendations. The lawsuit aims to implement the Stillwater Study’s recommendations to improve the flow regimes at Twitchell Dam and restore the endangered steelhead to good condition. Experts estimate that only 3-4% of Twitchell Reservoir water would be affected if enough water was released to allow fish passage along the Santa Maria River to and from the Sisquoc River.

A young angler catching and releasing steelhead on the upper Sisquoc River in 1979.

Endangered steelhead have nearly disappeared from river systems throughout the central coast due to dam construction and increased water usage. Today’s legal action seeks to restore one of our region’s most prolific fisheries while maintaining reliable water supplies for our farms and communities.

Southern steelhead were listed as endangered under the federal Endangered Species Act in 1997. Since then, several studies have identified the Santa Maria River system as a top priority for restoring steelhead fisheries throughout southern California. These studies also identify insufficient streamflows from Twitchell Dam as the primary factor limiting steelhead recovery in this watershed.

ForestWatch is represented in this matter by the Santa Barbara-based Environmental Defense Center, and SLO Coastkeeper is represented in this matter by Lawyers for Clean Water. The groups will present their legal arguments to the court later this summer as we work towards restoring one of southern California’s most important steelhead fisheries.

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