In response to the discussion of this topic at the December 2003 Task Force meeting, Representative Jackson considered information about water use and flows and state statutes to determine if Avistas hydropower water rights present a problem for existing and future water use in the basin.  He concluded that one cannot demonstrate now that the Avista rights present a problem for the Clark Fork River Basin and especially the Flathead subbasin.  A summary of his arguments follows.

 

Existing Basin Water Resources

The subbasin has abundant surface and groundwater resources.  The Flathead drainage has 3,500 miles of streams and 450 lakes including Flathead Lake. The usable water in Flathead Lake is 1,700,200 acre-ft.  The total volume is estimated to be 20 to 25 million acre-ft.  Hungry Horse Reservoir has 3,467,179 acre-ft usable water storage. The abundance of this water provides recharge to the ground water and most likely is the reason that the Bureau of Mines at Butte has found no decrease in the water table as a result of groundwater development to date.  The capacity of groundwater for development is not known, but is considered to be extremely large compared to the small amount of water being used for development each year.

 

Bad Data and Data Gaps

The existing data base on water appropriations and use can not be used to demonstrate that all of the water has been allocated in the Flathead subbasin because of missing and duplicate data.  Denise Deluca stated, Information describing existing appropriations of water represents the most significant gap in information and knowledge required for basin planning and management.  As a whole it cannot be considered to be accurate, consistent, and reliable.  Deluca lists many problems with the data.  Some of the problems are that existing water appropriations do not consistently specify the period of use. The rate and volume are not separated by use for each water right identification number. For a given identification number, either a rate or a volume were commonly found, but not both. Multiple entries for an identification number were found approximately 43% of the time. Priority dates were missing in some cases.

 

Also, in the water rights data, consumptive uses are not separated from non-consumptive uses.  Non-consumptive uses dwarf consumptive uses.  According to Marc Spratt, less than 1 million acre-feet in 76LJ (Flathead River) is allocated to consumptive uses while more than 7 million acre-feet is allocated to non-consumptive uses, primarily fisheries.  He also found that nearly all of the consumptive use on the South Fork lies in an irrigation right held by the Bureau of Reclamation which has not been utilized.  Also, correlation between allocation and actual use or depletion is unknown.  With consumptive uses, return flows are not considered.  For example, based on records of water use by the City of Kalispell, the return flow from domestic use is between 70 and 73%.  With irrigation the return flow is generally believed to be 44% to 50% but could be much higher.  In the case of non-consumptive uses, the return flow is generally 100%.  These data problems and data gaps prevent one from demonstrating that existing water uses have consumed the available surface or ground water in the Flathead subbasin.

 

 

 

 

Implication of Basin Water Use for Avistas Water Rights

As of June 2, 1998, Montanas Centralized Water Right Records System identified that the Clark Fork Basin had 26,274 surface water uses.  Thirty percent of these were junior to the most senior water right at Noxon Rapids Dam (35,000cfs with a 1951 priority date).  Only 3,125 uses are junior to the most junior Noxon Rapids water right (15,000 cfs with a 1976 priority date).  The uses of the water rights junior to Avistas as of June 2, 1998 by number were: 40% irrigation, 32% municipal, 16% stock water, and 12% unknown.

 

The impact of total basin irrigation on water available to Avista at its Noxon Rapids project is estimated in the following table.  Average yearly flow of Clark Fork River near Plains is 14,567,770 acre-feet (45 year average).

 

Total Basin             Water            Average        Average                   Depletion             Percent of

Acres Irrigated       Allotted          Used            Consumed                                          Annual Flow

470,000 ac             X 2.5 ft/ac      X .67 ac/ft         X .56              = 440,860 ac/ft           3.03%

428,000 ac             X 2.5 ft/ac      X .67 ac/ft         X .56              = 401,464 ac/ft           2.76%

411,000 ac             X 2.5 ft/ac      X .67 ac/ft         X .56              = 385,518 ac/ft           2.65%

 

Thus using three different estimates of the basins irrigated acreage, basin irrigation consumes between 2.65% and 3% of the average annual river flow at Plains.

 

As is seen in the following table, the growth in irrigation from 1950 to 1980, using data from the 1983 Depletion Task Force Report, consumes only about 0.44% of the average annual flow of the Clark Fork River near Plains.

 

                           Total Acres   Water         Average                 Average                 Percent

                           Irrigated        Allotted      Used                      Depletion

                                                                  Consumed

Prior to 1950       358,000 ac    X2.5 ft/ac   X.67 X.56        = 335,000 ac/ft               2.3%

1950-1980          69,000 ac      X2.5 ft/ac   X.67 X.56        =   64.000 ac/ft               0.44%

Total                   427,000ac     X2.5 ft/ac   X.67 X.56        = 400,526 ac/ft               2.75%

 

However, this figure is overstated because when the irrigated acreage was compiled, the irrigated acres were double counted in the reservoir records and change of use authorizations.  According to the Cunningham Report between the years of 1950 to 1980 the additional water use was 60,600 acre-ft which they state is .4% of the average annual flow in acre-ft at Noxon Rapids.  The Cunningham Report further concluded:  In the early 1950s Hungry Horse Dam was completed and has provided flow benefits to WWP (Avista) at both Noxon Rapids and Cabinet Gorge Dams.  It can be argued that these modified flow releases from Hungry Horse dam have mitigated any power losses that would have occurred from increased irrigation depletions in the Flathead.  Because additional development of irrigated acreage in the basin is very small, the development will not have an adverse impact on Avistas hydro power water supply. 

 

 

 

 

 

Historic River Flow Data

The USGS data on historic river flow at Polson, St. Regis, and Plains are shown below in Appendices 3, 4, and 5, respectively.  These data show that the 45 year average river flow since Avista built its hydroelectric dam at Noxon is higher than the preceding 45 year average.  This is true at all three water measuring sites:  Polson, St. Regis and Plains.  Also, the average for the last 10 years at each site is higher that the average for the last 45 years.  There is no evidence from the water flow data for the Flathead River and the Clark Fork Clark River that the water supply for Avista has been adversely affected.

 

 Subordination of Cabinet Gorges Water Rights

When Washington Water Power began to construct the Cabinet Gorge hydropower facility across the Montana border in Idaho on the Clark Fork, the Montana legislature wanted to ensure that the states ability to use water in Montana would not be limited by an out-of-state water use. The Montana Legislature passed the following statute in 1951:

85-1-122. Clark Fork River. The waters of the Clark Fork River maybe impounded or restrained within the state of Montana for a distance not exceeding 25 miles from the Idaho-Montana boundary line by a dam located on said river in the state of Idaho and constructed by any person, firm, partnership or corporation authorized to do business in the state of Montana. Any present or future appropriation of water in the watershed in the state of Montana for irrigation and domestic use above said dam shall have priority over water for power use at said dam.

This language subordinates any Montana water right held by WWP at Cabinet Gorge (36,000 cfs and 26,062,410 ac-ft per year with a priority date of 1951) to future irrigation and domestic water uses upstream of the dam. Cabinet Gorge Dam is located in Idaho but 98% of the reservoir behind the dam is located in Montana. This same provision was not enacted when Noxon Rapids was built which was about the same time.  The State of Idaho has a preference clause in its water right statute that places hydropower at the bottom of the preference list. (DNRC)

 

Options for the Clark Fork Basin Water Management Plan

In light of the preceding information, management options that should be considered for the Clark Fork plan include:

$ Develop local sub-basin water management districts;

$ Encourage water use and depletion data improvement;

$ Promote water conservation;

$ Develop drought plans;

$ Prevent dewatered streams;

$ Consider using ground water to prevent dewatering streams during critical periods;

$ Promote forest management; and

$ Consider Subordinating Avistas water rights.

 

The Task Force agreed to consider Rep. Jacksons arguments and revisit this topic at its next meeting.