Updates to CPNRD Board of Directors:

4/26/2012 Duane Woodward, hydrologist, reported that the committee recently put out proposals for contract bids to look at land use acres from 2006-2010.  The new data sets will be extensive, including 27 land types and uses.  Woodward said previous land use sets put together go back to the 1950s.

1/27/2012 Duane Woodward, hydrologist, reported that the Cooperative Hydrology Study is being calibrated and verified.  He said a focus area has been established to evaluate where calibration issues need attention and they will start adding drought period information soon.  A peer review is scheduled for March 2012.

6/30/2011 Duane Woodward, hydrologist, reported that the technical committee is getting ready to calibrate the models together with a completion date of July 13, 2011.  The group is also putting an RFP together in anticipation of peer review in November with the model up and running by December 2011.  The model will provide data on a five-year review of changes in depletions made to comply with management plans.

1/27/2011 Duane Woodward, hydrologist, reported that the COHYST Technical Committee has been successful at getting three computer models to work together simultaneously including the Watershed Model (CROPSIM), the Surface Water Model (STELLA), and the Groundwater Model (MODFLOW).  Together these models have 600-700 hydrographs and have provided good improvements to the understanding of groundwater scenarios. 

2/25/2010 Duane Woodward, hydrologist, gave a report to the Central Platte NRD board on updates to the Study. Currently, the technical committee is combining layers and calibrating the pumpage/recharge data to make it more diversified. There are also updates in the tracking and accounting that will allow for shifts in groundwater and surface water changes, as well as changes in streamflow due to retirement of irrigated acres. Woodward also reported that COHYST received a grant for $500,000 to combine the Conjunctive Management Study and COHYST data.

9/3/09 (August board meeting) Ron Bishop reported that the sponsors plan to apply for a Nebraska Environmental Trust Grant to hire a contractor to pay for a study on historic irrigated use, crop use and pumping. He also reported that the sponsors agreement is up for review and the Central Platte NRD will continue involvement.

7/23/09 Technical Committee lays out Phase III Operating Plan Click here for plan

5/7/09 Central Platte Natural Resources District Receives Grant from Environmental Trust

4/23/09 Duane Woodward, hydrologist, reported that their technical committee is continuing to work on the Phase III operating plan and the budget structure. Woodward said Upper Big Blue NRD will no longer participate as a sponsor due to the fact that the Study is going in a new direction and will not provide as much technical information for their District.

1/22/09 Duane Woodward, hydrologist, reported on the Cooperative Hydrology Study. He said the sponsors are currently putting together a plan for next year’s goals and budget. A couple of the new goals include developing an accounting model that would allow for annual changes to be made and interpreted to find out how much water is getting back to the river after all components are entered such as precipitation, climate, evaporation, reservoir and dam holdings, etc. Another goal is to hire a project management coordinator to determine what projects should take priority and to coordinate those projects.

10/23/08 Duane Woodward, hydrologist, reported that the sponsors group have outlined what tasks the group plans to accomplish within the next two years with the Cooperative Hydrology Study. The tasks include: looking at ways to bring the over-appropriated areas back to fully appropriated, evaluate the Platte River Program projects, look at transfers and offsets basin-wide, look at the balance between supply and demand for both long-term and short term (including the NRDs Groundwater Management Plans), and look at base flow changes with surface water projects within the COHYST area.

12/20/07 Duane Woodward, hydrologist, presented a preliminary report on the river depletions from 1997-2005. According to the latest COHYST model run, a total of 24,800 acre-feet will need to be offset within the five sponsoring NRDs to get back to the 1997 levels as required by the Nebraska Department of Natural Resources. Those NRDs include Central Platte, Tri-Basin, North Platte, South Platte and Twin Platte. Of the 24,800 acre-feet of offsets needed, Central Platte will need to come up with 2,400 ac/ft to honor a commitment to get back to the 1997 levels in just the over-appropriated area. Woodward said that HDR Engineering is currently working on a tool that will help determine how far back to go by looking at long-term trends. Woodward reported that modelers are also working on a model assessment from 1997-2005 to see how well the COHYST model predicted the drought.

11/15/07 Duane Woodward, hydrologist, reported that the Cooperative Hydrology Study sponsors would meet on December 4th to review draft depletions in the overappropriated areas for the Natural Resources District in the study area. The sponsors will also review the final Eastern model (CPNRD included), update COHYST assessments to be completed by June 2008, review percent depletions being run in the North Platte NRD and Twin Platte NRD. They are also working on a model to identify the effects of land use changes (such as a change from wheatland grass to corn.)

8/23/07 Duane Woodward, hydrologist, gave an update several on-going projects as part of the Cooperative Hydrology Study. New modelers at the North Platte and Twin Platte NRDs are updating the 1997-2005 models and calibrating the existing models. Dick Lucky, previously with USGS, is working on the over-appropriated areas and breaking them down per Natural Resource District. Woodward also reported that Parsons Engineering is calibrating the surface runoff component of the model and how it changes land uses.

Understanding the Cooperative Hydrology Study

The Cooperative Hydrology Study (COHYST) is a cooperative effort to improve the understanding of the hydrological and geological conditions in the Platte Basin. COHYST came about as a result of concerns by various Nebraska interests about what was being proposed by the three-state Platte River Cooperative Agreement and the quality of the information and data that was available to make the decisions that the U.S. Fish & Wildlife Service and the Cooperative Agreement Governance Committee were proposing to make.

What Led to Developing COHYST?

The Platte River Cooperative Agreement was entered into by Nebraska, Colorado, Wyoming, and the U.S. Department of Interior (represented by U.S. Fish & Wildlife Service and U.S. Bureau of Reclamation) in July of 1997. The purpose was to develop and implement a Recovery Implementation Program on the Central Platte River in order to protect the whooping cranes, the least terns, and the piping plovers, each a threatened or endangered species that have been known to utilize the Platte River. It was proposed in order to prevent the long delays and major costs that were being experienced by the many projects up and down the river.As project sponsors and owners attempted to get licenses, permits, approvals, or financial assistance from the federal government, they ran into reviews by the U.S. Fish & Wildlife Service because of the Endangered Species Act (ESA). A prime example of the delays and cost is the 15 years and over $30 million spent by Nebraska Public Power District and Central Nebraska Public Power & Irrigation District in trying to get their hydro-electric operations re-licensed through the Federal Energy Regulatory Com mission (FERC). Other Nebraska projects as well as projects in Colorado and Wyoming were facing similar delays, costs, and loss of water. (For an example of the potential magnitude of these ESA-related impacts, we can examine recent impacts to the Klamath River Project in Oregon and California lost all their water for one year).

The program proposed by the Platte River Cooperative Agreement consists of three major components:

1. Land for wildlife habitat on the Platte River
2. Increased flows in the river during times when U.S. Fish & Wildlife Service feels flows are too low for the benefit of those threatened and endangered species.
3. No new depletions to Platte River flows or flows to tributary streams.

This last item, “no new depletions,” was one that caught the attention of many Nebraskans because the Fish & Wildlife Service were proposing not only “no new depletions” caused by diversions from the Platte or it’s tributaries, but also “no new depletions” from groundwater pumping! What they proposed was to restrict or regulate the installation of new wells that, when pumped over time, would deplete the flows of the Platte River or any tributary flowing into the Central Platte.

Only Available Evaluation Tool Many Nebraskans were concerned with how the Cooperative Agreement participants (and ultimately the federal and state administrations) would likely decide what wells would “deplete” the river and how much or how little “depletion” would cause a new well to be subject to regulation. The proposed program would require any new well drilled after July 1, 1997 to “replace” any depletion to the U.S. Fish & Wildlife Service’s desired flows. These “offsets” would have to be made up by acquiring, by purchase or otherwise, an amount of water equal to the “depletion” amount and provide it back to the river at the appropriate time. With that kind of requirement, the decision on what wells would deplete flows and how much a well might deplete the U.S. Fish & Wildlife Service’s flows is a decision that would dictate whether or not a farmer could put in a new irrigation well to develop more land or whether he would be prohibited because of cost for “offset” water, as well as dictate the additional expense for municipal wells and industrial wells and whether or not a new industry would be discouraged from coming to the area. The only “tool” available to the U.S. Fish & Wildlife Service and the Platte River Cooperative Agreement’s Governance Committee to make those decisions and determine the level of impact from various wells was a simplistic formula developed by U.S. Geological Survey (USGS) called SDF which stands for Streamflow Depletion Factor.

Why Not Use SDF?

SDF only considers three fators:

1. Distance a well is from a river or stream
2. Average storage capacity of the aquifer
3. The average transmissivity (how fast water can move or pass through) of the aquifer.

SDF can be used to roughly estimate the magnitude of impact a pumping well will have on a river or stream in a given amount of time (example: A well located x miles from the river and pumped for 15,000 days (41 years) will have depleted the flow of the river by an amount equal to 28% of the total amount that well pumped during the 15,000 days, or in simpler words, 28% of the volume of water that well pumps in 15,000 days will show up as a depletion to the river in that 15,000 days).

While SDF is used extensively in Colorado and has been their basis for groundwater regulation, many Nebraskans were concerned that it was too simplistic and not accurate enough if it was going to be the basis for regulating new wells. It was also considered by many to be a method that would over-estimate the impact, and thereby over regulate wells and require offset water from new wells that shouldn’t be regulated and require more offset water from regulated wells than was necessary.

An Alternative to SDF Because of those general and widespread concerns a group of Nebraska interests joined together in early 1998 for the purpose of developing hydrologic and geologic databases that could later be used for groundwater modeling that would be more accurate than the SDF method and less likely to “overstate” impacts. The effort, called COHYST, was started to ensure that the decisions regarding the Platte River Cooperative Agreement were based on supportable science and data. To assure that the proper databases were gathered and constructed in a sound and scientific manner, the COHYST sponsors sought the assistance of independent outside consultants to advise them on managing the project and the best technical approach to use. Request for proposals were sent to a dozen or so firms and two firms, Parsons Engineering & Science and Hemmenway Groundwater Engineers were hired in 1998. U.S. Geological Survey (USGS) was hired in 1999 to provide additional technical advice to assist with the construction of the models.

* Parsons is a worldwide engineering and science consulting firm with one of their offices in Denver, Colorado.
* Hemmenway Groundwater Engineers is a Colorado firm specializing in groundwater investigations and having extensive experience in the mid-west.

The proposed Platte River Program was originally scheduled to be ready to implement in 2000 but as it drug on it became evident that there may be sufficient time to not only develop good databases but also to develop the more complex groundwater model prior to implementation of the Platte River Cooperative Agreement Program, and so in mid-1999 the participants interviewed and later hired three individuals to actually start building the groundwater models. Where SDF only considers distance, storage and transmissivity, the COHYST model is based on the much more complex “mod-flow”groundwater model that was also developed by USGS, but was developed to provide a much more detailed analytical tool than the more simplistic SDF method. COHYST breaks the study area down into small cell areas, or “nodes”, and each “node” is assigned its appropriate geologic, hydrologic, and surface features from the scientific data that was either gathered earlier or compiled from the studies conducted as part of COHYST.

Geologic and hydrologic data assigned to each node include such things as:

• Different geologic layers above the base of the aquifer
• Transmissivity and water holding capacity of each layer
• Location of any confining layers that would slow the vertical or horizontal movement of water
• Specific water yield of each layer
• Groundwater elevation.

Surface features and data assigned to each node includes:

• The location of any river, streams, or drains
• The soil types and characteristics
• Land use (whether land is dryland or irrigated crop, or even parking lots and roof tops)
• The location of irrigation, municipal and industrial wells
• Aquifer level and layer from which any wells withdraw their water

All of these and a host of other data like rainfall, water consumption of difference crops, runoff, and growing season; are all data used to “describe” each node. While each “node” has it’s own independent set of data and characteristics, the model ties the nodes together so they can interact with all the nodes adjacent to them. So, if you pump out a lot of water from one node, it can effect not only that node, but also the node(s) next to it.

Calibration The end goal of a properly calibrated groundwater model is to be able to simulate or predict groundwater elevations and groundwater interactions with rivers, streams and drains under a variety of conditions and over time. One of the primary ways of determining whether a model is properly calibrated is to see if it can replicate measured field conditions as they change over time.

Where Are We? By starting the model with conditions that existed in 1940 and running the model, adding the changes that occurred between 1940 and 1970, and 1980 and 2000, we determine if the model can replicate 1970, 1980 and 2000 groundwater conditions. Making the necessary adjustments so the model can replicate those historic conditions is a major part of the calibration process. That “calibration” stage is where COHYST is currently. The final stage of calibration is projected for October-December 2004. Once properly calibrated, whenever it might be, the model will be a valuable tool to assist Central Platte NRD Board of Directors as well as six other NRDs and the State of Nebraska in analyzing impacts on groundwater levels and impacts on stream flows of any proposed “changes” or proposed “regulations” to the surface and groundwater systems.

A far better tool than one that only looks at “depletion to a river” and only considers distance from a river and an average storage and transmissivity of an aquifer.

Who is Developing COHYST?

Sponsors of COHYST consist of:
*Seven Natural Resources Districts-Central Platte, Tri Basin, Twin Platte, South Platte, North Platte, Little Blue, & Upper Big Blue *Two Public Power Districts-Central Nebraska Public Power & Irrigation and Nebraska Public Power
*Two State Agencies-Nebraska Department of Natural Resources and Nebraska Game & Parks

Partners to the Sponsors include:
*Three cities-Grand Island, North Platte, and Scottsbluff
*Three statewide farm & irrigation organizations-Nebraska Farm Bureau, Nebraska Water Resources Association, Nebraska Water Users, Inc.
*Two environmental organizations-Nebraska Audubon Society and Platte River Whooping Crane Trust

Assisting and Participating in the efforts are:
*US Geological Survey *University of Nebraska *U.S.D.A.- Natural Resources Conservation Service

Providing Management & Technical Assistance & Direction
* Parsons Engineering & Science - A worldwide Engineering & Science Consulting Firm. Hired in 1998 by COHYST.
* Hemmenway Groundwater Engineers - A Colorado consulting firm specializing in groundwater. Hired in 1998 by COHYST.
* U.S. Geological Survey - Hired to provide additional technical advise on modeling. Hired in 1999.

What is the Cost?Total cost to Nebraska will be approximately $7,000,000.00 with the Nebraska Environmental Trust providing $2,895,000.00 or 41% through a grant. While the cost is a lot of money, it’s a lot less than the cost of losing industrial development or the prevention of developing new land because of an overstated impact. Central Platte NRD’s share will be $504,000.00 or approximately 7%, with $32,500.00 supplied in cash. The other $471,500.00 supplied in the form of in-kind-services (mostly staff time). This works out to be an average of $84,000.00/year ($5,500.00 cash and $78,500.00 in-kind services).

Contact: Duane Woodward

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