Flow and Water Quality:
Nearly all of the streams containing suitable habitat for steelhead/trout have to some extent, on-going water extraction activities for anthropogenic uses. This reduction of surface flows minimizes the available habitat for rearing fish, hinders upstream and downstream fish movement, and affects water temperature and water quality;
Pauma Creek contains perennial flows from its headwaters downstream to the Pauma Indian Tribe’s water diversion, which is located approximately 1/3 of a mile downstream of the Cleveland National Forest Service boundary. Thereafter, the stream loses surface flows during the mid to late summer months;
Gomez Creek, Pala Creek, Agua Tibia Creek, and Frey Creek contain only sections of perennial surface flows during the summer and early fall months. These sections may be sufficient to support small trout populations;
The lack of flows altogether or insufficient flows in the SLR River most likely would impede the passage of steelhead to these more suitable streams in the Northern Subbasin;
Water quality is being impacted by agricultural runoff that have direct access to streams;
There is a lack of water quality data on the streams in the Northern Subbasin. Results of a fall 2005 and spring 2006 bioassessment in Doane Creek indicated an Index of Biotic Integrity quality rating of “good” and “very good,” respectively.
The 2007 Poomacha Fire resulted in a large amount of sediment input to Pauma Creek that filled in deep pools as well as covered potential spawning gravels. In addition to fine sediment, log jams had formed from woody debris being carried downstream during significant rain events;
Other streams such as Agua Tibia Creek and Frey Creek, which were also within the burned area of the Poomacha Fire, may have experienced similar sediment inputs;
Large agricultural production has resulted in numerous terraced, steep hillsides. Although best management practices are in place, erosion from these hillsides most likely contributes fine sediments to the streams in the Northern Subbasin;
Livestock have unrestricted access to some tributaries, resulting in stream bank erosion;
Soils (and bedrock) in streams of the Northern Subbasin are prone to erosion, and slides and streambank failures have been observed to contribute fines to the streams.
Riparian Condition/Water Temperature:
Canopy cover on Pauma Creek and its tributaries (French Valley Creek and Doane Creek) was suitable for salmonids. In general, the Poomacha Fire did not adversely affect the canopy, as the fire, for the most part, did not burn in the riparian areas and remained a ground fire;
Canopy cover in Pauma Creek is also aided by the steep, canyon walls along much of the middle and upper portions of the creek and similar conditions may exist in other subbasin streams;
Water temperature data collected by CDFG during summer habitat inventories indicate suitable stream temperatures. However, these data are limited, and therefore inconclusive.
At the time of the 2007 and 2008 CDFG Pauma Creek habitat inventory surveys instream habitat conditions were considered poor to good depending on the habitat category. In the three surveyed reaches pool quality, pool depth, and pool shelter habitat characteristics fell below EMDS target values and were evaluated as unsuitable for steelhead trout. Conversely, canopy density and cobble embeddedness met EMDS target values and were evaluated as suitable conditions for steelhead;
Lower Pauma Creek has been modified as the creek has been straightened, lined with boulders, and all vegetation has been removed;
Marginal trout habitat was present in a small, surveyed portion of Gomez Creek, approximately 2 miles upstream of its confluence with SLR River. This area retained perennial flows with a robust canopy and a few potential spawning areas. It lacked deep pools and sufficient instream cover;
Similar habitat may be available in Agua Tibia, Frey Creek, and Pala Creek. Agua Tibia Creek appeared to retain surface flows for a longer duration, as witnessed during the summer of 2007 and late spring of 2008.
Suitable salmonid spawning areas were available in the surveyed reaches of the Pauma Creek and to a lesser extent Gomez Creek. In Pauma Creek, overall numbers of potential spawning gravels were moderate and embeddedness measurements met suitable EMDS target values;
The effects of the 2007 Poomacha Fire increased sediment input into the creek and most likely resulted in the burying of potential spawning gravels; nevertheless, numerous additional spawning areas were readily observed in a stream survey following the fire;
The accumulation of sediments as a result of the fire may require a series of winter storms in order to flush out these fine sediments and restore suitable spawning grounds throughout Pauma Creek.
Salmonid habitat conditions in Pauma Creek are rated as moderate potential refugia as it retains a healthy population of native, self-reproducing rainbow trout. In general, if fish passage modifications occurred at the Highway 76 Bridge, approximately ¾ of a mile to one mile of suitable spawning and rearing habitat would become available to steelhead trout. The potential habitat terminates at a ten-foot high, concrete wall located 2.4 miles above Highway 76;
Gomez Creek appeared to have a small stream reach of potential steelhead habitat, but without surveying downstream of this habitat it is not known if steelhead could access this area;
There are a few other tributaries, Agua Tibia Creek, Pala Creek, and Frey Creek, whose current habitat status is relatively unknown, but anecdotal records describe them as containing steelhead/rainbow trout habitat that was formerly utilized by these fish. Due to issues with accessibility and water extractions, available habitat may be more limited in these streams.
Several partial fish barriers exist along the lower SLR River that hinders/limits the potential for steelhead to utilize streams in the Northern Subbasin;
Fish passage barriers are present in Pauma Creek at the Highway 76 Bridge (RM 0.8) and 2.4 miles upstream of the Highway 76 bridge in the form of a 10-foot high concrete wall;
Other known barriers include the Pala Mission Road crossing in Pala Creek and in Gomez Creek at a road crossing 3.7 miles upstream its confluence with the SLR River. Additional barriers are most likely present in lower Gomez Creek, Frey Creek, and Agua Tibia Creek north of Highway 76.