Water Management

Bitterroot River Erosion near Gravel Pit-photo

"Where channel migration of the Bitterroot River is occurring, do not inhibit the river from establishing natural flow patterns during high flow events, where appropriate, to enhance existing riparian woodlands and provide suitable restoration sites for both gallery and riverfront forest vegetation that could provide breeding, nesting, feeding, or migration habitat for target species" (Bitterroot River management objective stated in the Refuge CCP, over the next 15 years).


Surface Waters

Dike Work in the 60's-photo Lee Metcalf Refuge receives surface water from: tile drain ditches, springs, ephemeral and perennial creeks, subsurface flow, and three lateral irrigation ditches (source majority). The North Lateral Ditch, Middle Lateral Ditch, and South Lateral Ditch are mapped in Figure 17 from the Refuge CCP. These lateral ditches are supplied by the Supply Ditch, a primary canal that carries diverted Bitterroot River water from Victor to just north of the refuge. Surface water entering the refuge from the east often has a high nutrient load as it traverses or drains out of grazed or farmed lands. As a result, the refuge receives nutrient-rich drainage water that results in abundant algal growth during summer months.

Aerial Photo of Pond 10 before Otter Pond-pondThe refuge has a complex system of irrigation ditches, springs, creeks, impoundments, and water control structures for moving water within the refuge to fill the various impoundments and to irrigate upland fields. In 1982, the refuge submitted 24 water right claims in response to State Senate Bill 76, which mandated adjudication of pre-1973 State water rights. These 24 pre-1973 claims total 31,297.88 acre-feet per year. There is also one post-1973 storage permit (300 acre-feet per year) and two domestic well permits (11.5 acre-feet per year) that increase the total refuge-owned water rights to 31,609.38 acre-feet per year (table 4). Most of these rights are supplemental, meaning the water sources are commingled to supply the refuge needs for optimum operation. In addition, the refuge receives up to 2,600 acre-feet per year (average diversion rate of 8.57 cubic feet per second) from the Supply Ditch Association to augment refuge water rights. This water flows through three lateral irrigation ditches and costs approximately $4,000 annually. Post-1973 claimed, permitted water rights total 34,209.38 acre-feet per year.

Bass Creek Water Control Structure-photoIn 2008, the Department of Natural Resources and Conservation of the State of Montana began examining water right claims for the refuge. In this process, a claims examiner reviews various elements to determine the validity and necessity of each claim. A preliminary decree is anticipated to be issued by the water courts in the next few years. After the objection process is completed and the water court is satisfied, the claim representing prior use and a final decree will be issued.

Flume Reading by Staff-photoWater is diverted on the refuge to store approximately 2,079 acre-feet of water on 795 acres of wetland impoundments. Water is also used for grassland units on approximately 205 acres. The main season of water use is from mid-March until early December. This varies with water conditions as determined by annual precipitation, snowmelt, and availability of water from the Supply Ditch. Adequate water is important to provide spring and fall migration stopover habitat for migratory birds and for irrigation of habitat restoration sites within upland fields during the summer. During the winter, most impoundments are kept full to provide water for resident species such as bass, aquatic invertebrates, and wintering waterfowl.


Bitterroot River

Bitterroot River Erosion near RR Trestle-photoAbout 10–15 miles north of Stevensville, the Bitterroot River channel is more confined, compared to its highly braided form farther south. Despite limited changes in river shape north of Stevensville, the river stretch along the refuge has maintained a highly dynamic, instable channel form due to its geological, topographic, and hydraulic position. The historical floodplain at the refuge was characterized by the following: (1) multiple abandoned channels (for example, Barn and Francois Sloughs) that were connected with the main river channel during high-flow events; (2) small within-floodplain channels (for example, Rogmans and Swamp Creeks) that received water from ground water discharge and occasional overbank backwater flooding during high-flow events; (3) entry of two mountain- or terrace-derived major tributaries to the Bitterroot River (for example, North Burnt Fork Creek and Three Mile Creek); (4) slightly higher elevation inter-drainage point bars, natural levees, and terraces; and (5) alluvial fans (figure 7).

Bitterroot River-Main Stem photo at WVAIn 1971, the refuge contracted the placement of riprap material along 1,250 feet of the east bank of the Bitterroot River west of McPherson Ditch (USFWS 1988–93). This riprap was subsequently eroded and moved by high riverflows; by 1984 the riprap was gone, and the bank at this location was moving eastward. Since the mid-1990s, levees built along the Bitterroot River, including the area where the riprap was placed in 1971, have eroded and been at least partly breached in places as the Bitterroot River attempts to move laterally (figure 14). Also, the Bitterroot River appears to be moving more discharge through the North Island Slough area immediately north of Otter Pond on the north side of the refuge. These river movements could potentially affect the north Otter Pond levee; cause water movement across other floodplain areas on the refuge; and affect other structures, roads, and the railroad bed.