The Ana River supplies the water that maintains the Summer Lake Wildlife Area wetlands.
 For most of its short 7 miles (11 km) course, the Ana River meanders through the Summer Lake Wildlife Area.
 It flows from a series of springs at the foot of Winter Ridge at the north end of the wildlife area to Summer Lake at the south end of the refuge.
 The river's source springs are located near and under Ana Reservoir.
The 60-acre (24 ha) reservoir is owned by the Summer Lake Irrigation District; however, the district's reservoir frontage is surrounded by the Summer Lake Wildlife Area property.
The springs provide a constant 52 °F (11 °C) flow year round.
 This helps the river maintain a relatively mild water temperature, even during the cold winter months.

After leaving the reservoir, the Ana River flows southeast for approximately 2 miles (3.2 km) with private ranch land on its north bank and the Summer Lake Wildlife Area on the south bank.
 Then for a short distance, the river passes through BLM land administered as part of the refuge.
 As the river enters the Bureau of Land Management area, it turns south, reaching the River Ranch Campground in the Summer Lake Wildlife Area in about 2 miles (3.2 km).
 The vegetation along this part of the river is dominated by big sagebrush, rabbitbrush, greasewood, needlegrass, ricegrass, and squirreltail.
 Native trees are rare along the Ana River except for a few Western juniper.

Just after the River Ranch Campground, the Ana River flows through a large impounded wetland.
 The wetlands and marsh pools cover approximately 4,500-acre (18 km²).
 In this area, a series of manmade dikes and channels maintain critical wildlife habitat.
 In the marsh, vegetation varies from sedges, rushes, and bluegrass in the meadows to cattails and bulrushes around the marsh pools.
 In the lower part of the river, the water becomes increasingly alkaline.
 Approximately 7 miles (11 km) from its source, the Ana River empties into the north end of Summer Lake.

The Summer Lake Wildlife Area is extremely important because its wetlands host hundreds of thousands of migratory birds each year.
 In 2005, the Oregon Department of Fish and Wildlife joined with the U.S. Department of Agriculture's Natural Resources Conservation Service, Oregon Hunters Association, Ducks Unlimited, and the North American Wetlands Conservation Council to enhance approximately 1,000 acres (4.0 km²) of seasonally flooded wetland habitat in the River Ranch area of the wildlife area.
 The project replaced a series of diversion structures along the Ana River supplying water to the adjacent wetlands.
 The project significantly improved the efficiency of the water management system, benefiting both the river and wetlands.
In 2009, the United States Army Corps of Engineers built three islands in the Summer Lake wetlands.
 The islands provide additional nesting sites for Caspian terns and other birds.
 The project was a joint effort by the Oregon Department of Fish and Wildlife, Army Corps of Engineers, Bureau of Land Management, United States Fish and Wildlife Service, United States Geological Survey, National Oceanic and Atmospheric Administration, Oregon Department of State Lands, and Oregon State University.
In 2010, a project financed by the State of Oregon, the Lake County Soil and Water Conservation District, Summer Lake Irrigation District, and Ducks Unlimited revitalized an additional 3,000 acres (12 km²) nesting habitat.
The Ana River supplies the water that maintains the Summer Lake Wildlife Area wetlands.  For most of its short 7 miles (11 km) course, the Ana River meanders through the Summer Lake Wildlife Area.  It flows from a series of springs at the foot of Winter Ridge at the north end of the wildlife area to Summer Lake at the south end of the refuge.  The river's source springs are located near and under Ana Reservoir. The 60-acre (24 ha) reservoir is owned by the Summer Lake Irrigation District; however, the district's reservoir frontage is surrounded by the Summer Lake Wildlife Area property. The springs provide a constant 52 °F (11 °C) flow year round.  This helps the river maintain a relatively mild water temperature, even during the cold winter months.
After leaving the reservoir, the Ana River flows southeast for approximately 2 miles (3.2 km) with private ranch land on its north bank and the Summer Lake Wildlife Area on the south bank.  Then for a short distance, the river passes through BLM land administered as part of the refuge.  As the river enters the Bureau of Land Management area, it turns south, reaching the River Ranch Campground in the Summer Lake Wildlife Area in about 2 miles (3.2 km).  The vegetation along this part of the river is dominated by big sagebrush, rabbitbrush, greasewood, needlegrass, ricegrass, and squirreltail.  Native trees are rare along the Ana River except for a few Western juniper.
Just after the River Ranch Campground, the Ana River flows through a large impounded wetland.  The wetlands and marsh pools cover approximately 4,500-acre (18 km²).  In this area, a series of manmade dikes and channels maintain critical wildlife habitat.  In the marsh, vegetation varies from sedges, rushes, and bluegrass in the meadows to cattails and bulrushes around the marsh pools.  In the lower part of the river, the water becomes increasingly alkaline.  Approximately 7 miles (11 km) from its source, the Ana River empties into the north end of Summer Lake.
The Summer Lake Wildlife Area is extremely important because its wetlands host hundreds of thousands of migratory birds each year.  In 2005, the Oregon Department of Fish and Wildlife joined with the U.S. Department of Agriculture's Natural Resources Conservation Service, Oregon Hunters Association, Ducks Unlimited, and the North American Wetlands Conservation Council to enhance approximately 1,000 acres (4.0 km²) of seasonally flooded wetland habitat in the River Ranch area of the wildlife area.  The project replaced a series of diversion structures along the Ana River supplying water to the adjacent wetlands.  The project significantly improved the efficiency of the water management system, benefiting both the river and wetlands. In 2009, the United States Army Corps of Engineers built three islands in the Summer Lake wetlands.  The islands provide additional nesting sites for Caspian terns and other birds.  The project was a joint effort by the Oregon Department of Fish and Wildlife, Army Corps of Engineers, Bureau of Land Management, United States Fish and Wildlife Service, United States Geological Survey, National Oceanic and Atmospheric Administration, Oregon Department of State Lands, and Oregon State University. In 2010, a project financed by the State of Oregon, the Lake County Soil and Water Conservation District, Summer Lake Irrigation District, and Ducks Unlimited revitalized an additional 3,000 acres (12 km²) nesting habitat.
Summer Lake Wildlife Area