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More study needed before going ahead with refuge addition

 April 18, 2005 by KEN RYKBOST, guest columnist Herald and News

The author Ken Rykbost recently retired as superintendent of the Oregon State University Klamath Experiment and Professor, Department of Crop and Soil Science. Opinions expressed are mine alone and do not represent Oregon State University, the Klamath Experiment Station, or Klamath County.

The proposed addition to the Klamath Basin Wildlife Refuge by purchasing the Barnes Ranch property and opening levies on Agency Lake and Barnes ranches described in the April 12 issue of the Herald and News will surely generate much interest and controversy.

Benefits including increased habitat for resident and transient waterfowl, increased habitat for endangered suckers, and potential improvements to water quality in the lake have been emphasized by proponents of adding these properties to the refuge. Everyone can agree that these are all desirable goals. What in my opinion has been lacking is an accurate evaluation of the real storage increase that would be achieved by the creation of additional shallow water storage within Klamath/Agency Lake.

Millions of private and federal dollars are being spent to improve water conservation in the Upper Klamath Basin. A significant portion of these expenditures has been used to purchase more than 13,000 acres of private property adjacent to Klamath and Agency lakes, retire it from agricultural use, and convert it to wetlands, water storage, or other non-agricultural uses.

The 7,159 acre Agency Lake Ranch was purchased in 1998 by the Bureau of Reclamation on the basis that it would increase storage by 40,000 acre-feet. I attended the presentation of this concept to the Klamath County Board of Commissioners by Bureau of Reclamation officials. It was not promoted as wetland restoration, wildlife habitat, or anything other than storage enhancement. To my recollection, there was no suggestion that the levy would be opened allowing open exchange with Agency Lake.

It became apparent that major dike improvements would be required to prevent leakage from Agency Lake Ranch to the Barnes Ranch. As a result, storage increase has been limited. In 2003, a below-normal water supply was anticipated and about 12,000 acre-feet of storage supplementation was achieved from Agency Lake Ranch.

25.000 stored

Delivering this water to the lake was accomplished over approximately 30 days by the pumping plant on the ranch, which has a capacity of about 400 acre-feet per day. Presently, an estimated 25,000 acre-feet is being held on the property.

Additional pumping capacity will be needed to deliver this water to the lake in a timely manner to minimize evaporative losses. As long as the property is isolated from the lake by levies, all available water, less evaporation losses, can be pumped to the lake.

The extent of settling of the soil surface has not been documented for these properties. It is likely to be from one to several feet. Natural Research Conservation Service personnel estimated soil settling on the Williamson River Ranch at 1 to 13 feet following drainage of the property (cited in a United State Geologic Survey publication authored by Snyder and Morace).

While some recovery may occur when the properties are inundated, land surfaces near Agency Lake will undoubtedly be lower than the adjacent lake bottom. If levy opening is employed to reconnect the properties to Agency Lake, some dead storage will result.

Under current operational mandates with opened levies, the extent of dead storage will be determined by lake elevation minimums established by the U.S. Fish and Wildlife Service biological opinion and the extent of land settling.

The storage increase volume estimate of 50,000 acre-feet for the combined properties has been based on some unspecified minimum elevation. It is probably based on the biological opinion's minimum lake elevation allowed in a critically dry hydrological year type, which is 4,137.1 feet (41,43.3 is full pool) above sea level.

This seems reasonable, as a slight rise in the property elevation from south to north is known to exist. An average depth of slightly more than 5 feet would be required to store 50,000 acre-feet on the 9,830 acres.

As year type improves from critical to dry, below average, or above average, minimum allowable lake elevation rises by nearly 1 foot for each class. Each increment reduces the usable storage capacity by a little less than 10,000 acre-feet.

In an above-average year type, available storage enhancement would be less than 30,000 acre-feet ,less evaporation losses during summer months. When connected to the lake by levy breaching, evaporation losses will extend over the full season and will be approximately 3 acre-feet per acre for open water surface area (less is used to irrigate pastures).

The amount of dead storage that would be generated by opening the levies to the Agency Lake is not a moot point.

How much settling?

If the average settling over the 7,159 acres has been 1 foot, dead storage with open levies would be 7,159 acre-feet. This is a direct loss against the proposed storage increase volume.

It is quite possible that settling has been considerably more than 1 foot. A topographic survey should be done to determine the extent of settling on both properties and allow an accurate calculation of the actual volume of dead storage that will offset storage enhancement achieved by opening the levies.

The proposed storage increase from combining both properties assumes no leakage. The experience with leakage from Agency Lake Ranch to Barnes Ranch suggests a similar problem will exist with levies on the Barnes Ranch, causing leakage to properties adjacent to the Barnes Ranch. Therefore, the suggested storage capacity of 50,000 acre-feet may only be achieved through extensive improvements to the levies at the north boundary of the Barnes and Agency Lake Ranches. Perhaps more importantly, the integrity of the levies on the Barnes property is critical if the Agency Lake Ranch levy is opened. A weak levy on the Barnes Ranch would jeopardize the lake and threaten to flood a large area in the Wood River Valley.

These issues should be fully investigated and accurate estimates of the actual storage capacity for each year type should be developed before going any further with the proposal. One additional point for consideration is the fact that once the levy is opened, the Agency-Barnes properties become critical habitat for endangered suckers by default. Could that result in a situation similar to the Clear Lake problem of sucker access into or out of portions of the reservoir?


 
NOTE: In accordance with Title 17 U.S.C. section 107, any copyrighted
material  herein is distributed without profit or payment to those who have
expressed  a  prior interest in receiving this information for non-profit
research and  educational purposes only. For more information go to:
 http://www.law.cornell.edu/uscode/17/107.shtml


 

 

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