Henry Hagg Lake

Washington County

Willamette/Sandy Basin

Location Area 1,153 acres (466.6 hect) Elevation 304 ft (92.7 m) Type reservoir Use irrigation, recreation Location 6 miles southw est of Forest Grove Access off Ore Hw y 47 via Scoggins Valley Road USGS Quad Gaston (24K), Y amhill River (100K) Coordinates 45˚ 28' 32" N, 123˚ 11' 50" W USPLSS tow nship 1S, range 04W, section 20

Henry Hagg Lake is a large multipurpose reservoir, created in 1974 by the Bureau of Reclamation with the construction of an earthf ill dam on in western Washington County. The reservoir was named in honor of Henry Hagg, a prominent dairyman and Washington County official who died in 1971. Scoggins Dam and Henry Hagg Lake form the primary component of the Bureau of Reclamation's Tualatin Project, which also includes the Patton Valley Pumping Plant, the spring Hill Pumping Plant, 20 booster Source: Oregon National Guard, 1981-82. View looking northwest. pumping plants, and 86 miles of piped lateral distribution system. To early settlers in the , the site of the modern project was known as "Twality ` Drainage Basin Characteristics Plains." It was one of the earliest farming settlements in Oregon. Agriculture developed Area 37.5 sq mi (97.1 sq km) Relief steep Precip 45-65 in (114-165 cm ) quickly because there were numerous open areas that permitted cultivation without the Agriculture expense and labor of clearing timber stands, and also because of the fertile soils in the Land Forest Range Water Irrig Non Irrig Urban Other Tualatin Valley. As the population increased, timbered tracts were cleared and more land Us e % 89.4 2.9 5.1 - 2.6 - - came under cultivation. Hay, grain, and livestock production were the basis for the early Note s - agricultural economy and are still important in the economy of the area. From a small start, irrigation increased substantially and it soon became apparent that storage of water would be Lake Morphometry M axim um Average needed. Also, flood and drainage problems had been a source of concern since early Area 1,153.0 acres (466.6 hect) Depth 110 ft (33.5 m) 51ft (15.6 M) settlement. Studies by the Bureau of Reclamation and Corps of Engineers made it clear that Ave/Max Depth Ratio 0.460 Volume 58,952 acre ft (72.82 cu hm ) irrigation and flood control were not the only water resource needs in the area. There was a Shoal area 9% Volum e factor 1.39 Shape factor 2.57 greater need for municipal and industrial water than originally anticipated. Construction of Length of Shoreline 12.2 mi (19.6 km) Retention tim e 1 yr the long Notes - considered project was finally authorized in 1966. Construction of facilities began in 1972 and they were completed in 1978. Scoggins Dam, a 151-foot high earthfill structure was W ater Quality completed in 1974 and the reservoir filled in 1975. Total capacity of Henry Hagg Lake at full Trophic status mesotrophic pool is 59,910 acre-feet, according to Bureau of Reclamation data. Sam ple date 10/07/81 Tem p 60.8F (16.0C) Diss. Oxygen (m g/l) - Benefits from the project have been several. Agricultural land has been more productive by Transparency 8.2 ft (2.5 m) Phosp (mg/l) 0.020 Cholorophyl a (mg/l) 5.1 providing a dependable water supply through the growing season, especially during the late Alkalinity 23 Conductivity (umhos/cm) 64 pH 6.6 summer period. The top 20,300 acre-feet of reservoir space is used for flood control, Major Na K Ca Mg Cl SO4 sufficient to completely regulate a flood the size which occurs about once in 50 years at the Ions 3.6 0.5 6.2 2.3 2.8 2.7 damsite. Another 14,000 acre-feet of water are used for supplemental municipal and Notes - industrial purposes for four communities. In addition, 16,900 acre-feet of water are made Sam ple date 05/09/75 Tem p 57.2F (14.0C) Diss. Oxygen (m g/l) 9.3 available to improve the water quality of the by scheduled releases of water in Transparency 10 ft (2.9 m) Phosp (mg/l) 0.010 Cholorophyl a (mg/l) - the summer when natural flows are low. Alkalinity 25 Conductivity (umhos/cm) 53 pH 7.7

Major Na K Ca Mg Cl SO4 Henry Hagg Lake has also become a very important recreational resource for people in the Ions 3.1 0.7 5.0 1.9 2.4 1.6 northern Willamette Valley. Boat launching and mooring facilities have been constructed and Notes All data from USGS there are large day-use areas provided with picnic tables, shelters, and water and sanitary facilities. Water-skiing is a popular activity at the lake; but the south end of the lake has a 10 mph speed limit for the benefit of sailors, swimmers, and other users. The lake is stocked develops in the lake in summer, with a sharp thermocline at about 30 feet (10 meters) depth. annually with rainbow trout and has rapidly become one of the state's more popular fishing There is some tendency for oxygen depletion in the deeper water, below 30 feet. In recent lakes. A fish trap was built below Scoggins Dam to collect, for hatchery use, the anadromous years, unwanted rough fish species in the lake have increased in numbers, and they compete fish blocked by the dam. Several dead trees were left in the reservoir to attract osprey, and with trout for food and space. Plans have been made by the Oregon Department of Fish and portions of the reservoir area are managed to provide winter range for elk and black-tailed Wildlife to chemically poison the lake to eliminate the unwanted species; however, this effort deer. has been postponed until 1984 because of funding cuts. The drainage basin contributing to Henry Hagg Lake is a 37.5 square mile area in the foothills of the Coast Range. Saddle Mountain, 3535 feet above sea level, is the highest point Concentrations of major ions in the lake are comparable to those in other Willamette Valley in the drainage basin, indeed the highest point in the northern . reservoirs which are influenced by turbidity, such as Fern Ridge Lake and Hills Creek Lake, Geologically the area is underlain by a mixture of sandstone and older volcanic rocks that and somewhat higher than in most other lakes and reservoirs. At times there are large flocks typify the foothills of the Coast Range. Thick soils of weathered clay and silt overlie the of ducks and other water birds on the lake and around the shoreline. The phytoplankton bedrock. A second-growth Douglas fir forest covers most of the drainage basin, with some occurring in the summer (McHugh, personal communication) are predominantly mesotrophic open grassland used for grazing; there are also some small farms. Land ownership in the to eutrophic diatoms (Asterionella Formosa, Synedra ulna), with occasional blue-green algal basin is, in part, private and, in part, federal (administered by the Bureau of Land blooms occurring at a few localities in the reservoir. Blooms of Volvox globator (a green Management). The shoreline of the reservoir was originally owned by the federal government alga) have also been observed and may be common to new reservoirs as it has also been (Bureau of Reclamation), although ownership has reverted to Washington County. observed in newly created Lost Creek Lake near Medford. Concentrations of phosphorus and chlorophyl, the water transparency, and the partial depletion of dissolved oxygen in the At full pool Henry Hagg Lake covers 1153 acres; it has a maximum depth of 110 feet, an hypolimnion all indicate the lake is highly mesotrophic. It is one of the more productive lakes average depth of 51 feet, and the water level fluctuates about 22 feet annually. It has, in in the Willamette Valley. It is common for new impoundments to be more eutrophic in the general, maintained good water quality since filling in 1975. However, some problems have first few years after flooding while the easily available nutrients in vegetation and in the developed in recent years. Because of its recent origin, the banks of the reservoir are not yet upper soil layers are entering the lake. The lake may shift to a lower trophic state as it stabilized and erosion and slumping produce local turbidity, particularly when waves are stabilizes with time. generated on the water surface by wind or motorboats. A pronounced thermal stratification

88 Atlas of Oregon Lakes

Source: NASA, 1980. Vertical photograph. Lake Reports 89