Emergent vegetation (primarily cattails) are encroaching on two Least chub refuge ponds located at the Tooele Army Depot South to the point that open water habitat has become much more confined, with the potential left untreated to impact the species. Nonnative Phragmites (common reed) is also becoming more extensive in the lower pond. Proliferation of willows around the perimeters, primarily the upper pond, has rendered access for biological sampling difficult and threatens to overwhelm portions of a fence encircling the upper pond.

1. Improve access by trimming willows and other vegetation surrounding the ponds. 2. Increase open water habitat for chubs in the ponds by selective removal of cattails and other emergent aquatic vegetation, and also some submerged vegetation and sediment on a limited basis, retaining an ample amount for breeding and cover (up to 25% of open water surface area). 3. Improve water conveyance efficiency between the two ponds via selective removal of terrestrial vegetation along the channel connecting them. 4. Process vegetation waste and transport composted material to various sites on the property for other beneficial uses. 5. Estimate and photo document decrease in target vegetation (area removed vs. area remaining) and increase in open area of ponds. 6. Continue to document densities of adult and juvenile least chub annually.

As the ponds continue to become more encroached by vegetation it will become less suitable for occupancy by least chub and increasingly difficult to collect and salvage fish prior to cleaning the ponds, which could result in higher rates of mortality of a sensitive species.

Utah Wildlife Action Plan. 2015. Least chub are listed as a Species of Greatest Conservation Need (S2/N1) under the WAP. Threats to its persistence include invasive nonnative species, both plants and animals. Nonnative common reed (Phragmites) has invaded the refuge pools and is spreading. Least chub are particularly sensitive because they exist largely as isolated populations with shrinking habitat due to droughts, water management, and encroachment of vegetation on their habitat. Conservation Agreement and Strategy for Least Chub. 1998. Goal is to ensure long-term persistence of Least Chub within its historic range and support development of statewide conservation efforts. Objectives include to: 1) eliminate or significantly reduce threats to least chub and its habitat to the greatest extent possible, and 2) restore and maintain a minimum number of populations throughout its historic range that will ensure the continued existence of Least Chub. The CAS's goal and both objectives are applicable to the proposed project.

N/A

Selective removal of submerged and emergent vegetation in the pond should help improve water quality by reducing the amount of decaying organic material in the pond, which increases biological oxygen demand and could therefore reduce dissolved oxygen levels during certain periods. Impacts to oxygen levels may be seasonal, such as during winter when the pond may freeze and oxygen exchange and circulation is more limited; and daily, such as during the night when plant respiration far exceeds photosynthesis. Proposed actions are not intended or expected to improve water quantity because only plants and saturated organic material (peat), and not sediment, are slated for removal. The DWR does not have any water rights at the WMA but there are no held downstream of the ponds. Water Rights has informed DWR there should not be significant issues if dredging is held to a minimum level. Sediment removal will largely be an artifact of removal of emergent vegetation to the rhizome (root).

N/A. DWR will take the necessary precautions to protect fish from harm due to proposed clearance activities to the maximum practicable extent and has jurisdiction over this State-listed species. There are no water rights issues at this site to affect work, however, we will exercise restraint with any sediment removal.

HEAVY EQUIPMENT: Tooele Army Depot personnel will utilize heavy equipment including a mini excavator and possibly a backhoe to help remove Phragmites from the lower pond, cattails from either pond, and as necessary, to perform some minor dredging usually coincident with removal of emergent vegetation. Heavy equipment may also be used to help clear some willows from around the ponds to facilitate access for monitoring, primarily the upper pond. All use of heavy equipment will be done under the guidance of DWR biologists. HAND CREWS: Personnel will utilize cutting shears and shovels (supplied by DWR) to remove upland and emergent vegetation in both ponds, but primarily the upper pond where vegetation encroachment is more severe. DWR biologists will oversee this work. Goal is to open up densely vegetated (emergent and submerged) but retain an sufficient amount (25% minimum pond coverage) as cover and breeding habitat for fish. SHREDDER: Removed vegetation will be stockpiled and fed into a shredder. Processed vegetation will be hauled away from the site for use elsewhere on Army Depot grounds. FISH SALVAGE: Remove as many fish as possible from ponds prior to activities and transfer to holding tank. Return fish to ponds when completed.

Habitat measurements will be taken before and after treatments. These will include emergent vegetation areal coverage, upland vegetation coverage, and pond depth transects (x, y). These will be repeated during annual surveys coincident with scheduled fish surveys. Results of this management effort will be summarized in a separate report.

Tooele Army Depot will be supplying heavy equipment (excavators and shredders) and personnel to help remove and process plant material.

This project is expected to be completed during one year, but because vegetation can be regenerated it will likely need to be repeated at some level of intensity in the future. That time frame should be extended through the proposed actions of removing selected emergent vegetation (native cattail and nonnative Phragmites) down to and including the rhizomes, by which they spread.

Least chub are listed as a Species of Greatest Conservation Need and recently were petitioned for the second time to be listed under the Endangered Species Act. Taking steps to prevent least chub from being listed under the ESA will be important to reduce economic impacts to Utahns. Federal listing could affect acquisition of water rights, groundwater pumping rates, cattle ranching practices, and housing development.

07/01/2022

06/30/2023

2023

The first stage of this project took place on 19-20 October 2022 and involved Tooele Army Depot (TEAD) and UDWR personnel. Work was more substantial on the downstream pond and required the pond to be drained prior to work being conducted. After an initial fish salvage, heavy equipment supplied and operated by TEAD was used to remove cattails and Phragmites and dredge this pond to create deeper open water habitat to provide refuge from potential low water conditions and improve longevity of the pond. Additionally, UDWR hand crews removed additional cattails from the center and edges of the upstream pond to limit the amount of disturbance to the Least Chub population which has historically been a slightly more abundant population than the downstream population. Heavy equipment was used in shallower water along the edge of the pond to grasp and pull larger clumps of cattail where it would not compromise the shoreline nor damage Least Chub habitat. Willow patches surrounding both ponds were selectively removed by heavy equipment to allow for more efficient access to the ponds for monitoring and management of the ponds. However, some patches were retained to provide some shading and also habitat for birds and mammals that utilize the area seasonally. Additionally in 2022, TEAD furthered the restoration efforts after this initial stage by installing a pipe to convey water between the two ponds to limit overgrowth of vegetation and debris from clogging the previous channel. This will help to ensure a more effective method of conveying water to the lower pond and reducing the amount of maintenance needed to clear the previous ditch. During the process of deepening the downstream pond, the original clay liner was damaged. Previous to this, however, water levels typically declined to an undesirable degree when a consistent water supply was not provided. Therefore, a new pond liner was installed by TEAD in the downstream pond before filling occurred to ensure the pond's ability to hold water. A new dedicated water supply system would help ensure that consistent and healthy water levels are maintained.

During past annual monitoring at the Tooele Army Depot ponds, it became apparent that encroaching vegetation in both ponds was beginning to limit Least Chub habitat in the upper and lower ponds. Cattails (Typha sp.) in the lower pond had become overabundant to the point that no open water habitat remained and nonnative Phragmites had begun to grow in patches. Additionally, the lower pond had become shallow, providing reduced habitat for least chub in low water conditions. Relatively little open water was remaining in the upper pond. Willows surrounding both ponds had increased the difficulty in accessing the ponds both by UDWR personnel conducting surveys and TEAD personnel conducting maintenance activities. On 13 September 2022, UDWR personnel met with TEAD to discuss and develop the project's goals and guidelines. Enhancing habitat for least chub, improving access to the ponds for monitoring and maintenance, and improving water supply security and conveyance efficiency between the two ponds were identified as high priority goals. The first stage of this project took place on 19-20 October 2022 and involved Tooele Army Depot (TEAD) and UDWR personnel. Work was more substantial on the downstream pond and required the pond to be drained prior to work being conducted. After an initial fish salvage, heavy equipment supplied and operated by TEAD was used to remove cattails and nonnative Phragmites and dredge this pond to create deeper open water habitat to provide refuge from potential low water conditions and improve longevity of the pond. Additionally, UDWR hand crews removed additional cattails from the center and edges of the upstream pond to limit the amount of disturbance to the Least Chub population which has historically been a slightly more abundant population than the downstream population. The intent was to create a mosaic of deeper open water and open up some shallower, warmer habitat but still leave enough cattails to provide habitat for fish and invertebrates as forage. Heavy equipment was used in shallower water along the edge of the pond to grasp and pull larger clumps of cattail where it would not compromise the shoreline nor damage Least Chub habitat. Willow patches surrounding both ponds were selectively removed by heavy equipment to allow for more efficient access to the ponds for monitoring and management of the ponds. However, some willow patches, particularly the taller ones, were retained to provide some shading and also habitat for birds and mammals that utilize the area seasonally. Additionally in 2022, TEAD furthered the restoration efforts after this initial stage by installing a pipe to convey water between the two ponds to limit overgrowth of vegetation and debris from clogging the previous channel. This will help to ensure a more effective method of conveying water to the lower pond and reducing the amount of maintenance needed to clear the previous ditch. During the process of deepening the downstream pond, the original clay liner was damaged. Therefore, a new pond liner was installed by TEAD in the downstream pond before filling occurred to ensure the pond's ability to hold water.

During UDWR annual monitoring of the least chub population, observations will be made of the growing extent of aquatic and terrestrial vegetation at each of the ponds and assessments made of the potential need and timing for additional maintenance. At these times there should also be some opportunity for limited, small-scale removal of emergent vegetation by hand in key areas. The next monitoring of the chub population is scheduled for 7 September 2023 and at that time the UDWR will also make an assessment of the aquatic and terrestrial vegetation approximately 10 months after the treatment. Water supply at this refuge site is intermittent and relies on uncertain availability. This issue is compounded by previous drought conditions making it difficult to supply adequate water to keep both ponds full, especially the lower pond. As part of the next phase of this project, UDWR has proposed an ESMF project (Tooele Army Depot Least Chub Ponds Water Supply System, No. 6556) to increase the reliability of the water supply. A buried pipe would be installed to connect the refuge ponds directly to the water source to continuously convey water to the ponds. This effort, scheduled for summer or fall of 2023, will increase the long-term security and management efficiency at these ponds. To help ensure that the new water supply functions properly and maintains adequate water levels for the Least Chub, a draft grant agreement is currently under development outlining the responsibilities of the UDWR and TEAD moving forward.