A draft federal study recommends taking out the earthen causeway that allows hikers and bicycle riders to reach Bateman Island in the Columbia River in Richland.

No bridge is proposed in the U.S. Army Corp of Engineers environmental assessment and feasibility report, which looked at ways to improve conditions for salmon.

That would leave the island only accessible by boat under the favored alternative in the study.

Now the causeway is used by the public to fish, hike and watch birds on Bateman Island. The Columbia Basin Audubon Society leads bird walks on the island on the first Saturdays of the month from fall to spring.

Public meetings on the proposal are planned Thursday, Feb. 23.

The causeway from the Richland Wye Park to Bateman Island, which is 500 feet long and 40 feet wide, was built of earth in the 1940s for agricultural access. Rock riprap has been added since then.

“It is a complete barrier to river flow, boats and fish,” the draft study said.

Issues were compounded when McNary Dam downstream on the Columbia River was completed in 1957.

The dam turned the southern side of the Yakima River delta into a backwater with ideal habitat for predatory fish and invasive plants, according to the draft report.

Hot river temperatures

Summer water temperatures on the south and west side of Bateman Island now can be as high as 86 degrees for sustained periods.

The warm water creates ideal conditions for non-native fish, such as smallmouth bass, that prey with voracious appetites on young salmon migrating to the ocean in the spring.

It also may prevent salmon from entering the warmer Yakima River to spawn.

The warm, stagnant and shallow backwater south of Bateman Island supports the growth of stargrass and algae that causes extreme daily fluctuations of dissolved oxygen, the report said. Salmon are more sensitive to oxygen concentrations than warmer water predatory fish.

The warm water and blocked flow at the mouth of the Yakima River acts as a choke point for all salmon and steelhead upriver in the Yakima Basin as they migrate out to the ocean and return to spawn, said Mike Livingston, regional director for the Washington state Department of Fish and Wildlife.

Historic populations of 500,000 salmon and steelhead in the Yakima Basin have dropped to 10,000 in the last century.

Several salmon stocks have recently been reintroduced upriver in the Yakima, including coho, spring chinook, summer chinook and sockeye, but they must navigate the delta on their journey to and from the Pacific Ocean.

“There are hundreds of millions of dollars we are investing throughout the (Yakima) Basin to improve conditions for fish,” Livingston said.

Pacific lamprey also have been reintroduced into the river.

The warm water may keep them from entering the Yakima River until later in the fall when water temperatures drop. Or they might continue up the Columbia River to overwinter, with just a few still entering the Yakima River the following spring, the draft report said.

Partial removal of causeway?

The draft report also looked at the possibility of taking out only part of the causeway, leaving 275 feet extending from the shore toward the island.

But it concluded that the remnants of the causeway would create a place for predatory fish to lurk in pockets of slow water and ambush salmon smolts as they passed through the section of the river between the end of the causeway and the island.

A 2004 study by the Corps with the city of Richland proposed breaching the causeway but continuing to provide access to the island on foot.

However, the cost of providing a bridge if the causeway is removed entirely would be expensive and there are also concerns that digging to build the structure could interfere with Native American cultural resources, according to federal and state officials.

Native Americans have used the island since at least 16,000 years ago, according to the draft study. The Lewis and Clark Expedition of 1805 documents that the island was used then by Native Americans for drying fish.

The study notes that removing the causeway could help clear sediment from the Yakima delta and create better conditions for boaters looking for opportunities to fish in the delta.

Other proposals for Bateman area

The draft study also considered other possible alternatives, some of them suggested at an earlier public meeting, and dismissed them without full study.

They included piping cooler water into the river, which was deemed unfeasible, or dredging the Yakima River where it meets the Columbia River.

Sediments may be contaminated and dredging must be minimized to comply with the Clean Water Act, the report said.

The report also looked at whether to do some work to reintroduce native vegetation along the shores of the island, including replacing the steep island bank with gradual steps.

However, that would increase the cost of work to remove the causeway, which already was estimated at $12.9 million. The cost would include $9.7 million in federal money and $3.4 million in state money.

The Corps is proposing the Bateman Island project under a program that caps federal spending at $10 million.

Comment on Bateman Island draft

The draft report is one step, but an important one, toward a final decision on the Bateman Island causeway, Livingston said.

The report was required to have a nonfederal sponsor, with the Department of Fish and Wildlife taking that role.

“We recognize that there’s a broad community invested in the outcomes of this project, and we share their commitment to the long-term health of the Yakima River delta and a solution-oriented, community-based approach for what comes next,” he said.

With the possibility that Bateman Island might no longer be accessible on foot, the Department of Fish and Wildlife is also interested in suggestions on how recreation could be improved in the general area of the island, such as adding fishing piers, Livingston said.

To comment on the draft feasibility report and environmental assessment of Bateman Island email NEPANWW@usace.army.mil using the subject line “Yakima River Delta.”

Or you can send them by mail to U.S. Army Corps of Engineers; ATTN: PPL-C (Yakima River Delta); 201 N. 3rd Ave.. Walla Walla, WA 99362.

Deadline for commenting is March 10.

Comments also will be heard and questions answered at open houses noon to 2 p.m. and 3 to 6 p.m. Feb. 23 at the Reach museum at 1943 Columbia Park Trail in Richland.