Why Tule Lake NWR Sump 1B is going dry

By Ducks Unlimited Biologist Amelia Raquel; John Vradenburg, USFWS – Klamath Basin National Wildlife Refuge Complex supervisory biologist; and Brad Kirby, Tule Lake Irrigation district manager

The Klamath Basin of southern Oregon and northern California is arguably one of the worst irrigation allocations in history, so why is the U.S. Fish and Wildlife Service draining water off a large wetland at Tule Lake National Wildlife Refuge (TLNWR)?

Sump 1B at TLNWR, is a 3,500-acre wetland and an important nesting, brood rearing and molting area for a large number of waterfowl in California. Sump 1B is going dry, not because of a lack of water in the system, but because it is no longer providing quality habitat for waterbirds.

Despite their name, permanent wetlands must go dry at some point to maintain productive wetland communities. Over time, prolonged flooding results in an unconsolidated wetland bottom that lacks the capacity to secure emergent plants, reduced abundance of submergent plants, and changes in diversity and abundance of the invertebrate community.

The result is a wetland that is less valuable for waterbirds. Under natural wet and dry cycles, climatic conditions drive wetland succession, but in highly altered, heavily managed systems the timing of these wetland disturbances has to be artificially created to ensure the habitat and food benefits are available for wildlife. On large wetland basins like Sump 1B, these management actions are expensive and require the collaboration of wetland scientists, irrigation districts and local agricultural producers to ensure success.

A drawdown on Sump 1B is not a new concept. The first drawdown of Sump 1B was a multiyear drawdown and refill cycle that from 2000 through 2003. Prior to these drawdowns Sump 1B was solid open water essentially void of any wetland vegetation. The marsh habitat that exists today which covers a large portion of Sump 1B, particularly the eastern half, was a result of the initial drawdown cycle. It was then drawn down in 2008 and again in 2009, to help revive the health of the wetland. Refuge staff estimate the benefits from a drawdown last between seven and 10 years, meaning this unit was long overdue and past its prime in providing habitat to waterfowl and other waterbirds.

The reason that a drawdown on Sump 1B does not occur more frequently is due to the cost required to pump water out of the wetland. Historically, these costs were much lower, making it more feasible. Pumping costs today are 30 to 40 times what they were. That coupled with budget cutbacks has made it much more challenging for the refuge to draw down the sump at the desired frequency.
TLNWR, in partnership with Ducks Unlimited (DU), the Tulelake Irrigation District (TID) and Bureau of Reclamation (BOR) worked to secure funding to conduct a drawdown on Sump 1B during the summer of 2020. Funding for the summer 2020 drawdown is the result of funding originally secured in 2012 from the Natural Resource Damage Assessment as part of the Cosco Busan Oil Spill Damage Assessment and Restoration Plan/Environmental Assessment. These funds were awarded to aid in a drawdown of Sump 1A (adjacent to Sump 1B) with the goal of exposing wetland soil to promote the germination of perennial wetland vegetation like cattail and bulrush which large grebes use to build nesting platforms. Because a drawdown of Sump 1A is not feasible due to financial and infrastructure constraints, the Refuge and partners opted to shift a portion of these funds to Sump 1B. By drawing down Sump 1B now, as opposed to waiting for funding to work in Sump 1A, similar benefits will be achieved for large grebe nesting habitat, but with ancillary benefits to waterfowl and other waterbirds.

So, if there is a lack of water in the system this year, why is the refuge actively removing water from one of the wetlands that has water? Confusing this even more is the older, larger Lower Klamath National Wildlife Refuge has been plagued by inadequate water deliveries for decades, plunging the refuge into a prolonged, unnatural drought.

Many concerned groups are investing time and money to look for solutions, but the issues on these two refuges are completely different. Lower Klamath National Wildlife Refuge is mostly dry because of over allocation of water supplies in the Upper Klamath Lake and Klamath River system, reduced project supply to the Klamath Project and the increased pumping costs of D-Plant.
TLNWR is generally safe from these pressures because it is in TID at the end of a large portion of the Klamath Project agricultural water delivery system.
This is a complex and efficient system that captures and utilizes irrigation return flows and natural runoff, which means for the most part, the TLNWR receives appropriate water deliveries every year. The challenge at TLNWR is removing water for managed wetland succession, so a drought year is the optimal time to draw Sump 1B down. Less water in the system means less water to pump out, and therefore lower costs than in most other years. This action benefits TID because water from Sump 1B can help maintain the required water elevations in adjacent Sump 1A for endangered sucker fish species and provide irrigation to agricultural producers.

Providing water management flexibility to TID ensures the continued ability to provide irrigation on BOR leased and refuge cooperative farmlands, which are integral in providing additional nutritional benefits to migratory waterfowl during the fall and spring migration.

Although you may have thought the sump was looking dire, if you’ve been by Sump 1B recently, you may have noticed the sea of green plants starting to emerge. The vast majority of those plants are smartweed and goosefoot, very favorable duck foods.

So, come fall when Sump 1B is refilled with water, it may actually provide more food than any other unit on both refuges this year.