Bureau of Reclamation releases study regarding Grand Lake clarity
The Bureau of Reclamation has completed its Preliminary Alternative Development Report that addresses concerns regarding the clarity of Grand Lake as well as possible alternatives for improving the clarity of the lake.
The study was conducted in response to water clarity standards put in place by the Colorado Water Quality Control Commission in 2008 that are expected to take effect by 2015.
Some of the alternatives for improving the clarity of Grand Lake that are discussed in the report include: Stopping pumping at the Farr Pumping Plant in July, August, and September; modify pumping at the plant during these three months; bypass Grand Lake with a buried pipeline and pump flows directly to Adams Tunnel; or bypass both Grand Lake and Shadow Mountain Reservoir with a buried pipeline and pump flows directly to Adams Tunnel.
Two standards for the clarity of Grand Lake were adopted by the Colorado Water Quality Control Commission in 2008.
The first standard is a narrative clarity standard requiring “the highest level of clarity attainable, consistent with the exercise of established water rights and the protection of aquatic life,” according to the report.
The second standard is a numerical clarity standard of a 4 meter Secchi disk depth that will be assessed by comparing 85 percent of available recordings from the months of July, August, and September. That means at least 85 percent of the measurements taken during those three months must meet the 4 meter Secchi disk depth standard, while 15 percent can be below the minimum requirement.
A Secchi disk is a circular disk used to measure the water transparency in oceans and lakes that is mounted on a pole and lowered into the water until it is no longer visible. The measurement is attained by lowering and raising the disk until an average depth of clarity is established.
The first documented clarity measurement in Grand Lake took place in September 1941 and was 9.2 meters. This was prior to the Colorado-Big Thompson project pumping.
Secchi disk measurements taken during 2007 to 2009 in Grand Lake, after the Colorado-Big Thompson Project started pumping, show a range of measurements from 1.4 meters to 4.9 meters with a seasonal trend toward degradation between July and late August or early September.
The report finds that stopping pumping, bypassing Grand Lake, bypassing Grand Lake and Shadow Mountain Reservoir, and a combination of stopping and modifying pumping should be included for further refinement and consideration.
The next step
This study is considered a launch pad for further investigations into problems, opportunities, and future needs related to Grand Lake clarity, said Kara Lamb, spokesperson for the Bureau of Reclamation.
A technical review of these four alternatives is the next step in the process and is scheduled to begin by fall of this year and be completed by fall of 2013, Lamb said.
During the next phase of the process, the bureau will be collaborating with other stakeholders in the project including Grand County, Northern Water Conservancy District, and various other Colorado-Big Thompson stakeholders, to examine the feasibility of each alternative in terms of costs, benefits, and environmental impacts.
Northern Water, the company that jointly operates the Colorado-Big Thompson project with the Bureau, helped to fund the Bureau study that was just released and they are also currently seeking a 1041 permit for the Windy Gap Firming Project from Grand County to allow more water to be pumped to the East Slope.
The Windy Gap Firming Project is separate from the efforts to improve Grand Lake clarity. However, the projects are related as they are both part of the overall efforts to mitigate the impacts of sending West Slope water to the East Slope.
“We feel we have the obligation to address the clarity standards of Grand Lake regardless of what happens with the Windy Gap Firming Project,” said Dana Strongin, a public information officer for Northern Water.
Windy Gap Firming Project
The 1041 permit that is being sought by the Municipal Subdistrict of Northern Colorado Water Conservancy, called the Subdistrict, identifies in a memorandum of understanding for the Grand Lake Clarity Project that the clarity of Grand Lake is an issue that they will take steps to improve if the permit is authorized by the county commissioners. Part of the memorandum is the completion of the study by the Bureau of Reclamation.
Deliberations by the Grand County Commissioners for the 1041 permit took place Tuesday, Aug. 28, and were continued to 1:30 p.m., Oct. 2, and all day Oct. 3. The commissioners have until Nov. 29, to make a final decision concerning the permit.
No decisions were made during the meeting that took place Tuesday and the commissioners will begin to discuss the Intergovernmental Agreement in October, said Lurline Underbrink Curran, Grand County manager.
Reducing nutrient loading
The Subdistrict has identified a nutrient reduction program for water that is pumped into Grand Lake and plans to complete these efforts if the permit is approved by the county.
The efforts include non-point source reductions (an example of non-point source reductions would be ranches decreasing the amount of fertilizer they use) as well as improvements to water treatment facilities, estimated to cost $3.3 million.
While nutrient reduction and water treatment facility improvements are currently included in the 1041 agreement, implementing the alternatives that are identified in the Bureau’s report are not a part of the 1041 application.
The completion of the projects outlined in the Bureau of Reclamation’s report are not a requirement of the 1041 agreement but they show the good faith efforts of Northern Water to sustain a good and working relationship with the West Slope, Strongin said.
The mitigations outlined in the 1041 agreement aim to make sure no additional damage is done to the system, while the Bureau of Reclamation’s report takes the first step in a process to look at what could be done to address the Grand Lake clarity issue, Strongin said.
The full report from the bureau can be found at usbr.gov/gp/ecao.
All of the documents for the Windy Gap Firming Project can be found at the Grand County website by going to co.grand.co.us/GCHome/1041permit/.
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