Naches River FMO Habitat

Overview

The Naches River is the main tributary of the Yakima River entering just north of the city of Yakima. It begins approximately 45 miles upstream at the confluence of the Bumping and Little Naches rivers (the American River flows into the Bumping River about 3.5 miles above this point). Other major tributaries of the Naches River include the Tieton River and Rattlesnake Creek. With the exception of storage dams, which block upstream migration on the Bumping and Tieton rivers, bull trout are able to migrate freely within the system. Below these dams there are 16.5 miles of habitat available to fish on the Bumping River and 21 miles on the Tieton River. Numerous smaller tributary streams also flow into the Naches River.

Habitat Conditions

The shared FMO habitat for all of the Naches River fluvial bull trout populations is considered to be primarily located in the Naches River although there is some evidence that the Tieton River and mainstem Yakima River are used as well. It is difficult to summarize habitat conditions in the Naches River given the length of the river (45 miles). Generally, the upper 27 miles (above the Tieton River confluence) flows through forested lands of mixed ownership. Much of this is National Forest but there are also areas that are privately owned; residences and groups of residences are ubiquitous with a few small farms present lower in the reach. There is also considerable recreational access and use. State Route (SR) 410 runs adjacent to the river for the entire length of this segment and has impacted floodplain function. Below the Tieton River confluence land use along the Naches River converts to predominantly agricultural (orchards, irrigated pasture, and hay production) and there are numerous water diversions. U.S. Highway 12 runs adjacent to the river from the Tieton River confluence downstream to the mouth impairing floodplain function. Haring (2001) describes numerous positive habitat attributes such as good riparian condition (in the upper portion of the river), good pool frequency and depth, good LWD and substantial amounts of off-channel habitat. These positive attributes combined with the length of river available for bull trout habitation suggest that FMO habitat conditions in the mainstem Naches River are not limiting population productivity for Naches River fluvial bull trout populations.

Tieton River FMO Habitat

The significance of the Tieton River as FMO habitat for the Naches River fluvial populations is unknown. However, adult bull trout have been captured in the Tieton River (in the stilling basin directly below Tieton Dam) that genetically assigned to the Rattlesnake Creek and American River populations (Small et al. 2009). The Tieton River flows for just over 23 miles from the base of the dam to its confluence with the Naches River. U.S. Highway 12 parallels the river on the left bank for much of this length, which has altered the riparian corridor. However, this road has little effect on floodplain function as the river is naturally confined in this section. Other roads, structures, several developed campgrounds, and the Yakima-Tieton diversion dam contribute to the rivers disturbed condition. The channel is in poor condition due to structural restrictions and an almost complete absence of LWD (Haring 2001). The most significant negative impact on fish habitat in the Tieton River is the regulated flow regime, which also contributes to the lack of LWD and channel complexity. The timing and magnitude of stream discharge in the river is the most highly altered of any in the Yakima Basin. Winter flows are 60-80% less than would occur under unregulated conditions and flow variability is extremely low. At a time when overwintering bull trout would be seeking pool habitat with cover, relatively none exists. During the first week of September an extreme, managed hydrologic event (“flip-flop”) occurs when dam releases are rapidly increased and average river flows often exceed by an order of magnitude what would be a natural base flow, sometimes exceeding 2,000 cfs. This condition persists to varying degrees for over a month.

Threats - NEED GROUP INPUT

Connectivity

Fish Passage Barriers

Threat Severity: Unknown, likely insignificant

Bull trout populations using Naches River as FMO habitat are not limited by natural barriers within the FMO habitat. Tieton and Bumping dams reduce metapopulation dynamics and geneflow. Nelson dam, a fish passage barrier on the mainstem Naches River near the Yakima River confluence was removed in 2023.

Low flows in parts of the Naches River during late summer may impact connectivity, however, bull trout intending to spawn usually migrate to their spawning grounds in June and July when flows are more adequate.

ANYTHING I MISSED???

Entrainment

Threat Severity: NEED INPUT

Several diversions exist along the Naches river. DOES ANYONE KNOW ANYTHING ABOUT NACHES RIVER ENTRAINMENT?

Dewatering due to flow management

Threat Severity: Insignificant?

Naches River FMO habitat is not known to dewater.

Land-use Issues

Forestry

Threat Severity: Unknown

Figure X. Timber harvest boundaries in the Naches River watershed. Colors denote different harvest time frames. Colors on the map range from 1991- Present.

There has been some timber harvest in the Naches River watershed over the past 35 years (Figure X). The harvest has primarily occurred upland of the river and away from known spawning tributaries, but there may be some impacts to FMO habitat, like increased sedimentation from erosion and roads, and reduced recruitment of large wood to the river. Those impacts are unquantified.

Agriculture and Grazing

Threat Severity: Unknown, likely insignificant

Livestock grazing occurs along the Naches River but habitat degradation significant at the reach scale is not believed to occur. About 50% of the grazing allotments in the Naches Watershed are for sheep, which are moved constantly by shepherds and should have minimal impact to the riparian areas.

The Okanogan-Wenatchee National Forest has been working on an updated environmental impact statement (2025) for grazing allotments in the Naches watershed, which has included input from members of the Yakima Bull Trout Working Group in an attempt to minimize any negative effects to bull trout.

Recreation

Threat Severity: Unknown, likely significant.

Recreational impacts to bull trout in Naches River FMO habitat are not quantified but are likely to be a threat. There has been riparian and aquatic habitat degradation due to recreation, including heavy use of established and dispersed camping sites and day use areas. When fires are allowed, campers remove and burn downed wood that may otherwise be recruited to the river. Rock dams are a persistent issue, but few are channel spanning. Pollution including trash, human waste, and road run-off may be impacting water quality.

There is heavy recreational use in the Little Naches drainage, including hundreds of miles of ORV trails, which may increase sedimentation and down-stream impacts in Naches FMO habitat.

There have been no reports of non-angling harassment of bull trout, but due to proximity of camp sites near river and bull trout large size and visibility fish may be harassed.

Roads and Development

Threat Severity:

Residential development is present in FMO habitat but is not thought to cause significant habitat degradation considering the extent of FMO habitat

High road density in little naches and OHV use could be source of sedimentation

Mining

Threat Severity:

Ecological Interactions

Brook Trout

Threat Severity:

Brook trout present but no hybrids have been identified through genetics analyses. Significance of threat is unknown

Other Invasive Species

Threat Severity:

Diminished Prey Base

Threat Severity:

Anadromous fish runs severely depleted from historic levels. Juvenile anadromous salmonid prey is scarce or not available. Impact is unknown but could be significant. Dearth of anadromous carcasses robs stream of marine-derived nutrients that likely drove invertebrate productivity. Impact is unknown but could be significant

Disease

Threat Severity:

Water Quantity and Quality

Flow issues/dewatering

Threat Severity:

Threat is not present. High flows in lower Naches during flip-flop but pre-spawn bull trout are well upstream by the time they occur

Altered flows in FMO habitat are result of reservoir releases from Bumping and Tieton Dams. Impacts associated with this mechanism are unknown but believed to be insignificant

Current and modeled future temperature conditions

Threat Severity:

Fisheries Impacts

Angling Regulations/Fisheries Use/Poaching (Recreational)

Threat Severity:

Legal angling for other species does occur in the American and Naches rivers. Illegal angling for bull trout may also occur. Unknown impact from incidental or targeted takes but could be moderately significant.

Management/Monitoring (Research)

Threat Severity:

Other Threats

Low Population Resiliency

Climate Change

Wildfire impacts (sedimentation, increased water temperature)

---

Actions

Future link/ iframe to PowerApp will go in this section.

Update Notes

2012 BTAP text copied into Yakipedia and edited to match new format in February 2025 by Aimee Taylor. ADD LINK TO 2012 BTAP pdf placemark

Additional edits proposed by Alex Conley, Aimee Taylor and XXXXXXX small group. Reviewed, and updated and approved by BTWG in XXXXXXXXXXXXX

Specific detail on out of cycle updates: