Hyatt Reservoir (Jackson)

Reachcode: 18010206001001 | Area: 810.1 acres | Shoreline: 7.7 mi | View on Interactive Map

(From Atlas of Oregon Lakes, Johnson et al. 1985)  Hyatt Reservoir, a large impoundment located just east of the Cascade crest in southern Oregon, was formed in 1923 with the completion of a rock-faced, earthfill dam on Keene Creek. Although developed privately, it now forms an important component of the Talent Division of the Rogue River Basin Project, a multi-purpose water resource project of the U.S. Bureau of Reclamation. Howard Prairie Lake, the largest reservoir in this project, is three miles to the northeast. These reservoirs, although located in the Klamath drainage basin, store water for transfer and use in the Rogue River drainage basin where they contribute to irrigation of about 35,000 acres in the Medford area. Hyatt Reservoir stores the runoff from the headwaters of Keene Creek and releases them downstream to Little Hyatt Reservoir. From there, the water joins the outflow from Howard Prairie Lake and is transported via the Ashland Lateral Canal to Emigrant Lake, a component of the Project upstream from Medford.

The small, forested drainage basin of Hyatt Reservoir is a mixture of private land and federal land administered by the Bureau of Land Management. The shoreline itself is predominantly federal land and the B.L.M. has designated it as the High Lakes Recreation Site with associated facilities such as campgrounds and boat launches. There is also a private resort on the lake providing recreational services. Hyatt Reservoir has been heavily used for water-based recreation for many years and supports a good population of rainbow and brook trout. It is not fished as much as Howard Prairie Lake, but pressure from anglers has increased in recent years. This entire region of the Southern Oregon Cascades is also quite popular with winter sports enthusiasts.

Hyatt Reservoir is not deep; the average depth is only 18 feet and the water is well-mixed, so that much of the bottom is exposed to warm surface water. Thus, the recycling of algal nutrients is enhanced. Major ion concentrations are somewhat higher than in nearby Howard Prairie Lake, as are conductivity and alkalinity. Water transparency is limited to 5.6 feet (1.7 meters). These factors, combined with chlorophyll and phosphorus concentrations, all suggest a classification as eutrophic. In 1968 the reservoir was treated with the poison rotenone to eliminate rough fish. As a result, the trout population has flourished, a further indication that a productive food chain exists. The reservoir was the site of an illegal attempt to introduce a non-native fish (pike) in 1973. Past experience with introductions of foreign species indicates that they can be an especially dangerous environmental modification. Fortunately, the pike appear not to have survived in Hyatt Reservoir.


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The list below includes results of zebra and quagga mussels surveys conducted by the Center for Lakes and Reservoirs and other agencies. The results "non-detect" and "results pending" indicate that surveys for zebra and quagga mussels were conducted, but none were detected or results are pending. For more details on zebra and quagga mussel monitoring, please visit the Online Mussel Monitoring Map.

Date Status/Species Source
Aug. 22, 2013 non detect Portland State University
July 11, 2013 non detect Portland State University

The list of plants below includes results of aquatic plant surveys conducted by the Center for Lakes and Reservoirs as well as aquatic invasive plant species detections that have been reported to iMap Invasives: an online, GIS-based invasive species reporting and querying tool.

Plants listed in the table below are categorized as native to Oregon, on the Oregon Department of Agriculture’s (ODA’s) Noxious Weed List, on the Federal Noxious Weed List, or non-native but not listed as noxious. Federal Noxious Weed List plants are plants determined by USDA to be serious threats to U.S. agriculture, irrigation, navigation, public health or the environment (7 C.F.R. 360.200). The ODA Noxious Weed categories are:

ODA Class A - weeds either unknown or with small enough infestations to make eradication or containment possible; targeted for eradication or intensive control.

ODA Class B - regionally abundant weeds (may have limited distribution in some counties); targeted for local/regional control on case-by-case basis.

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Date Species Status Source
Aug. 22, 2012 Myriophyllum hybrid (hybrid of Eurasian and northern milfoils) Non-native CLR
Aug. 3, 2011 Sagittaria sp. (arrowhead) Native CLR
Aug. 3, 2011 Elodea canadensis (common elodea, Canadian waterweed) Native CLR
Aug. 3, 2011 Potamogeton crispus (curly leaf pondweed) Non-native CLR
Aug. 3, 2011 Myosotis sp. (forget-me-not) Native CLR
Aug. 3, 2011 Potamogeton gramineus (grass-leaved pondweed) Native CLR
Aug. 3, 2011 Chara sp. (muskwort) Native CLR
Aug. 3, 2011 Sparganium angustifolium (narrowleaf bur-reed) Native CLR
Aug. 3, 2011 Eleocharis acicularis (needle spikerush) Native CLR
Aug. 3, 2011 Myriophyllum sibiricum (northern watermilfoil) Native CLR
Aug. 3, 2011 Eleocharis sp. (spikerush) Native CLR
Aug. 3, 2011 Nitella sp. (stonewort) Native CLR
Aug. 3, 2011 Ranunculus aquatilis (water-buttercup) Native CLR
Aug. 3, 2011 Myriophyllum sp. (water-milfoil) Native CLR
Aug. 3, 2011 Persicaria amphibia (water smartweed) Native CLR
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