Key Issues

Southern California steelhead are currently blocked from accessing potentially suitable habitat in the Middle Subbasin by natural barriers in the SLR River canyon, the Escondido Canal diversion dam and numerous other fish passage barriers located downstream of the subbasin;

The regulated timing, duration, and amount of flow releases from Henshaw Dam are likely not conducive to the lifecycle requirements of salmonids;

Warm water game fish present in the river would pose a major threat to the successful completion of the early lifecycle stages of steelhead/trout;

The decreased magnitude and frequency of flood flows has resulted in the buildup of fine sediments and decreased size and number of pools.

Findings Related to Issues

Flow and Water Quality:

The regulated timing, duration, and amount of flow releases from Henshaw Dam is not necessarily conducive to the lifecycle requirements of salmonids;

When water is not released from Henshaw Dam during periods of low flow, water temperatures and water quality are adversely affected. In addition to areas of the river going dry, stream water temperature increases could spur algal growth, which in turn, depletes the dissolved oxygen content, and the overall water quality may deteriorate;

The decreased magnitude and frequency of flood flows has resulted in the encroachment of vegetation into the stream, a buildup of fine sediments, and limited pool habitat;

Commercial groundwater harvesting near the headwaters of Cedar Creek removes tens of thousand of gallons of groundwater daily, reducing the amount of water flowing into Cedar Creek and thus into the SLR River.

Erosion/Sediment:

High amounts of fine sediment were observed throughout the surveyed area in shallow pools, pool tail-outs, and riffle habitats;

Soils (and bedrock) in streams of the Middle Subbasin are prone to erosion, and slides and streambank failures have been observed to contribute fines to the streams.

Riparian Condition/Water Temperature:

Streamside tree canopy providing shade over the water was generally suitable for the surveyed area. In addition to shrub and trees, some additional stream shade may be provided by areas where canyon walls are in close proximity to the river;

The 2007 Poomacha Fire burned the riparian habitat along the SLR River (western portion of subbasin) at a moderate severity with patches of high burn severity. During a post-fire visit to the Escondido Canal diversion dam, the riparian along the river appeared to be intact, but most of the surrounding hillsides were burned and moderately to highly denuded of vegetation;

Water temperature data collected by CDFG during spring habitat inventories indicate suitable stream temperatures. However, these data are limited, and therefore inconclusive;

NMFS employed a data temperature logger in the SLR River in the Cleveland National Forest proper during the spring of 2008 and will monitor the temperature extreme period during the summer and early fall months.

Instream Habitat:

Limited suitable spawning and rearing habitat were present in the SLR River within the surveyed area. Deep complex pools are lacking in the river as all of the reaches received poor EMDS ratings in pool quality, pool depth (except reach 3), and pool shelter;

The relatively high embedded substrate observed from pool tails and the relative shallow pools are indicative of the lack of significant stream flows to scour deeper pools and remove excessive fine sediments;

Warm water game fish were present throughout much of the surveyed area. If trout were provided access these fish would likely predate on the various lifecycle stages of trout;

Tributary habitat was inaccessible due to fish passage barriers, but appeared to be limited even above these barriers.

Gravel/Substrate:

Suitable salmonid spawning areas were available but limited in the subbasin. High embeddedness levels in pool tail-outs potentially limit successful egg incubation and the development and emergence of salmonid fry;

The post-fire effects of increased sediment input in the western half of the subbasin most likely resulted in buried spawning gravels that will require another series of storms in order to flush out these fine sediments and restore suitable spawning grounds.

Refugia Areas:

Salmonid habitat conditions in the Middle Subbasin are generally rated as low quality/low potential refugia. 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 habitat that is currently present is generally of poor quality; however, with seasonally appropriate flow releases from Henshaw Dam that would allow proper hydrologic processes to occur, the subbasin’s habitat suitability for trout could greatly increase;

Limited suitable habitat exists in the tributaries that were examined and are currently contain fish passage barriers near their confluences with the SLR River (see below).

Barriers:

In addition to the natural waterfalls in the SLR River canyon and the Escondido Canal diversion dam located just to the west of the subbasin, several natural waterfall and bedrock chute barriers were also observed in the SLR River in the Cleveland National Forest proper. These are partial, low flow barriers and under the right flow conditions, may be passable;

Wigham Creek is impassible at Highway 76, approximately 300 feet upstream of its confluence with the SLR River, as a culvert is perched four and half feet above a shallow pool. Prisoner Creek contains a long, steep bedrock chute near its confluence with the SLR River that would seem impassible to fish.