Evaluating the Effects of Operations to Avoid Adverse Impacts to Downstream Water Deliveries
* How do Reclamation operations affect the suitability of water to meet downstream delivery requirements for end users including municipal, agricultural, recreational and threatened and endangered species issues related to water conditions?
River systems are experiencing increased loadings of nutrients and chemicals such as pesticides and other compounds. By virtue of their location, Reclamation dams can concentrate compounds or exacerbate suitability issues due to eutrophication. Specific design criteria inherent in some facilities (e.g., withdrawal location) and seasonal and daily operations potential add to the problems. Our objective is to determine how specific operations are exacerbating conditions, and what potential solutions exist to minimize impacts.
Need and Benefit
Most Reclamation reservoirs were originally built to provide hydropower, flood control, and a stable water supply. As population and land use patterns continue to change in the Western United States, so have changes in demands upon Reclamation projects, and consequently Reclamation's mission. Decisions about operations are now based not only upon maintaining a reliable water supply but on making sure it is suitable for downstream uses that including the typical end-users, agriculture and municipal, as well meeting the needs of fisheries, endangered species and recreational uses are also.
We have provided a basic level of applied research at several reservoirs where issues have arisen that potentially impact Reclamation's operations--either through lost hydropower revenues or an impaired ability to deliver water. Although these projects are focusing on specific reservoirs, the issues they address are not unique to these systems, and results are broadly applicable. This is a collaborative effort, and Reclamation's presence at meetings and during the study have been very beneficial from a scientific and political standpoint--as it shows Reclamation's willingness and interest to address these important issues. Study design is done in concert with cooperators to ensure as many of the objectives as possible are achieved. All work to date has been done on a cost-share basis, with either dollar-for-dollar matching and/or in kind services.
In Montana, we have been studying Canyon Ferry Reservoir, and the effects that releases low in dissolved oxygen have had on the reservoir downstream of it. This study initially started with the State of Montana notifying Reclamation of violating dissolved oxygen standards below Canyon Ferry Dam, potentially impacting the recreational fishery there. This once-prosperous fishery also provided food for overwintering bald eagles. We are using the data collected to describe the extent of the problem and to possibly help identify modifications to operations at the Canyon Ferry Dam to minimize impacts. We initially demonstrated spills would enhance the oxygen level in the river below the dam; however, this resulted in significant losses of hydropower revenue, as much as $6,000 per day, and potentially could impact downstream water supplies. Water would need to be spilled as much as 60 days a year. Currently, GE Hydro has indicated a willingness to invest time and research into exploring modifications to the structure that would help alleviate the dissolved oxygen problem. Such changes would minimize any impact to operations, yet still achieve the desired downstream conditions This study was originally to end in fiscal year (FY) 2002, but will likely extend through FY 2005 as testing continues.
Research at Tiber Reservoir is being conducted to determine if changes in operations (i.e., the addition of a power house) will significantly impact that reservoir. The powerhouse will significantly change the way water is released from the reservoir, possibly affecting nutrient budgets within the reservoir and downstream. As new issues arise, the program is adaptable to new reservoirs. Depending on levels of support, we try to move to at least one new reservoir or issue every year. Projects last three years in an effort to encompass a wide range of potential environmental variability from wet to dry years
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