Key Issues

Southern California Coast Steelhead are currently blocked from accessing potentially suitable habitat in the Upper Subbasin due to the presence of Henshaw Dam, Escondido diversion dam and multiple other fish passage barriers located downstream of the subbasin;

The W.F. SLR River is currently the only stream in the subbasin to maintain resident, native trout populations;

Warm water game fish, present in the Lake Henshaw, W.F. SLR River, and potentially other streams in the subbasin pose a threat to trout successfully completing their early lifecycle stages;

Without sufficient precipitation to sustain surface flows, many streams in the Upper Subbasin contain only small sections of perennial flows.

Findings Related to Issues

Flow and Water Quality:

Stream flows are seasonal in all streams in the Upper Subbasin with some streams maintaining areas with year round water. Low water flow most likely influences water quality and instream water temperatures;

During these low-flow conditions, water quality and instream water temperatures may be unfavorable to trout;

Periods of grazing cattle beyond the Warner Ranch’s carrying capacity and severe drought have degraded water quality and riparian plant communities in streams and in Lake Henshaw (water quality);

The numerous wells located on the Warner Ranch may reduce the amount of water available for riparian species and reduce overall surface flows in the SLR River or its tributaries;

In general, there is a lack of water quality data on the streams in the Upper Subbasin.

Erosion/Sediment:

There is a lack of data concerning erosion/sediment in the streams of the Upper Subbasin.

Riparian Condition/Water Temperature:

Generally, streamside canopy appeared to be lacking in many of the subbasin’s streams lower reaches near their terminus into Lake Henshaw. These streams’ canopy cover may increase further upstream;

According to a 1978 W.F. SLR River survey report, the three mile section that maintains a trout population contained a mature riparian with nearly 100% canopy closure. More recent surveys on the WF have noted the existence a suitable riparian canopy;

Water temperature data is lacking in the streams in the subbasin. Without an extensive canopy and coldwater seeps, it seems likely that instream water temperatures during the summer and early fall extreme period would be unfavorable for trout.

Instream Habitat:

None of the streams in the Upper Subbasin were surveyed as a part of the watershed assessment; therefore, the condition of instream habitat in the subbasin’s streams is relatively unknown;

Previous surveys on the W.F. SLR River have noted suitable habitat conditions for trout such as, suitable spawning gravels, presence of moderate to deep pools, and mature canopy cover;

Warm water game fish are present in the W.F. SLR River and could inhabit other streams in the subbasin. These fish would predate on the various lifecycle stages of trout.

Gravel/Substrate:

Based on the self-sustaining, resident trout population in the W.F. SLR River, suitable salmonid spawning areas are available in this stream. Other streams with similar geology may possess spawning gravels as well.

Refugia Areas:

Salmonid habitat conditions in the Upper Subbasin are generally considered unknown as far as potential refugia due to the lack of recent surveys. The W.F. SLR River was considered medium potential because of its current trout population and its watershed boundaries located almost entirely within the Cleveland National Forest;

The subbasin is currently inaccessible to steelhead. Numerous downstream fish passage barriers would need to be modified in order to allow trout to have access to the area. The limited sections of permanent stream flow would be a limiting factor for potential refugia areas for trout.

Barriers:

In the West Fork SLR, rainbow trout are limited to a three mile reach at approximately three miles upstream of the confluence with Lake Henshaw, where they are confined by an upper and lower falls;

Fish passage barriers may be present on some of the streams that drain into Lake Henshaw. Stream surveys are needed to determine the presence/absence of any potential barriers.