Solving Water Problems in the Klamath Basin
A Proposed Solution by the Klamath Basin Rangeland Trust
September 15, 2002
Klamath Basin Rangeland Trust
James Root, Chair
Klamath Basin Rangeland Trust
c/o Fort Klamath Properties
P.O. Box 129, Medford, OR 97501
(541) 722-5653 Extension 117
Kurt Thomas, Secretary/Treasurer
Klamath Basin Rangeland Trust
c/o Thomas Cattle Company
5401 California Avenue, Suite 30, Bakersfield, CA, 93309
William Winner, Board Member
Klamath Basin Rangeland Trust
Professor, Department of Botany and Plant Pathology
Oregon State University, Corvallis, OR 97331
Chrysten Root, Geologist/Hydrologist
Pacific Groundwater Group
2377 Eastlake Avenue East, Seattle, WA 98119
I. Executive Summary
Competing water demands in the Klamath Basin now exceeds supply. Water
shortages are particularly acute during years of low rainfall. Increasing
water quality and quantity will help stabilize the economies for
downstream farmers, ranchers, fishermen and Native Americans.
One of the Klamath Basin’s sub regions — the Wood River Valley — presents
a unique opportunity to transform a landscape dominated by irrigation and
grazing, into habitat that conserves water and allows the return of
wildlife. This proposal involves:
The acquisition of water rights in the Wood River Valley to enable a
curtailment of irrigation and reduction of cattle grazing.
Disabling dikes that now exist around Agency Lake to restore the water
storage capacity and environmental benefit of adjacent wetlands.
Changing water use in the Wood River Valley will permit water, otherwise
used for flood irrigation, to naturally flow into streams and lakes, which
will improve the quantity and quality of water resources throughout the
entire Klamath Basin. If grazing is reduced, the landscape will again
support thriving populations of important wildlife species, including bald
eagles, red band rainbow trout, shortnose and Lost River suckers and other
The Wood River Valley represents the best opportunity to quickly and
efficiently provide a new source of clean water to those in desperate need
of water further downstream:
Rivers and streams of the Wood River Valley provide about 25% of the
water feeding Upper Klamath Lake. Leaving water in the streams that is
currently used for flood irrigation, will nearly double the current flow
of the Wood River and add a lake foot of water to Upper Klamath Lake
during the irrigation season — 60,000 to 80,000 acre-feet of water (200 to
270 cfs) during the irrigation season
The Wood River Valley occupies only 5% of the land area of the upper
Klamath Basin but currently supports about 50% of the cattle. Reducing
grazing to sustainable levels without irrigation, will result in an
immediate, direct improvement in Klamath Basin water quality, by
decreasing amounts of phosphorus in the waters draining to Agency Lake. In
turn, this will increase riparian vegetation and promote biodiversity in
aquatic and terrestrial habitats.
Disabling dikes near Agency Lake will restore wetlands, assist the
efforts of other entities to improve water quality, add to water storage
capacity and reduce expenses for operation and maintenance of the present
dike system. Disabling the dikes may provide an additional 45,000
acre-feet of water.
Implementing this plan will economically benefit local residents who
actively seek opportunity for positive change. Transformation of the Wood
River Valley as herein proposed, can be quick and efficient because water
rights are controlled by only 15 rancher/owners, most of whom are
1. The Klamath Basin: Overcommitted Water
The Klamath Basin, located in Northern California and Southern Oregon, is
now well known for its inability to supply enough water to meet the
competing demands of its water users. The water supply for Upper Klamath
Basin comes from three major river rivers, each with its own, unique
valley (Figure 1). Water from the Wood River flows into Agency Lake, which
then drains into Upper Klamath Lake. Water from the Williamson River and
its tributary, the Sprague River, drains directly into Upper Klamath Lake.
Upper Klamath Lake is the primary water source for the Klamath Basin
Irrigation Project and the Klamath River.
The fundamental problem is that water resources in the Klamath Basin are
over committed and cannot meet all of the demands. Competing water needs
include those for agriculture, endangered fish species, Native American
fishing rights and downstream fishing communities. For example, in the
year 2001, the water supply was insufficient for agriculture because of
drought and increased instream flow requirements for endangered fish
species. The result was lawsuits filed by farmers and ranchers, public
protests, law enforcement officers guarding water distribution control
points and disruption of the Klamath Basin’s economy.
In addition to the need for additional water in the Klamath Basin, there
is also a growing need to improve the quality of water in the Klamath
Basin. In particular, nutrient loading to Upper Klamath Lake and water
temperatures must be reduced in order to protect endangered species and
facilitate recreational use of the lake. Natural variation in annual
precipitation ensures that there will be years in the future when the
water supply is inadequate to meet the needs of the Endangered Species
Act, agriculture and other users. The most feasible way to improve both
the quantity and quality of water in the Klamath Basin is to develop a new
supply of water through conservation efforts.
The general goal of this project proposal is to increase the quantity and
quality of water in the Klamath Basin by conserving irrigation water in
the Wood River Valley. The Wood River Valley is located in south, central
Oregon and includes five creeks and innumerable artesian springs which
flow into Agency Lake (Figure 2). The valley is currently used for high
density cattle grazing. The current grazing capacity is made possible by
an elaborate irrigation system that diverts spring fed creeks and rivers
onto pastures and that drain the low lying, wetland areas allowing cattle
to forage. Our proposal is to acquire or lease water rights in order to
stop this irrigation. When irrigation is curtailed waters of the Wood
River Valley will remain in their streambeds, drain naturally into Agency
Lake and flow to the downstream portions of the Klamath Basin. The Wood
River Valley will be managed back to its natural state by elimination of
water diversions, irrigation ditches and drainage ditches. The pastures in
the Wood River Valley will return to a natural state allowing a limited
number of livestock to exist on a sustainable basis.
The proposed transformation of the Wood River Valley presents a unique
opportunity because the natural resource values of the Valley now outweigh
the agricultural values. Implementation of this proposal will result in a
significant new supply of water that is of higher quality than that
currently flowing from The Wood River Valley. The proposed land use change
takes no land from agricultural production, poses no threat to those
currently holding water rights in the Wood River Valley, contributes to
the conservation goals for habitat restoration needed by wildlife and
moves water use from irrigating pastures to a higher agricultural
2. Project Overview
The proposed Wood River Valley Project has three basic goals:
Goal 1: Increase Water Supply to Downstream Uses in the Klamath Basin.
Estimates of the new supply of water produced by curtailing irrigation in
the Wood River Valley range from 200 - 270 cfs during the crop growing
season. Water is of a premium during the agricultural growing season (May
through September), since the growing season coincides with the period
when water is most needed by endangered fish species. The new water supply
provided by the curtailment of irrigation in the Valley is enough to raise
Klamath Lake by at least one foot and is enough to meet the water deficit
existing for downstream users except during the most extreme conditions.
Goal 2: Restoration of Wetlands and Pastures.
A key aspect of the proposed project is the restoration of 15,000 acres of
wetlands. The wetlands are located on the northern boundary of Agency Lake
and are currently separated from the lake by an extensive system of dikes
and drains. Development of a comprehensive resource management plan for
these wetlands, that includes conservation of habitat for endangered
species and establishment of hydraulic connectivity between the wetlands
and lake, is essential to the ecology of the Wood River Valley. Such
restoration would also provide an additional 45,000 ac-ft of water to the
lake and downstream users on an annual basis. The restoration of pasture
lands in the Valley would primarily include fencing of riparian and
wildlife corridors and instream restoration to improve spawning and
rearing habitat for endangered and protected fish species. The proposed
reductions in cattle populations would protect upland habitats for
endangered and threatened terrestrial species as well. The proposed
restoration activities do not generally require large investments, but can
instead be accomplished by natural processes.
Goal 3: Improve Water Quality in Rivers and Lakes.
The phosphorus inputs from rivers and streams into Agency Lake and Upper
Klamath Lake result in enormous blooms of algae. The algae deplete oxygen
levels in the lakes to levels below those needed by fish, including the
endangered short-nosed and Lost River sucker species. In addition, the
high water temperature of rivers and streams during summer are detrimental
to migrating fish including endangered salmon and sucker species. The
Total Maximum Daily Loads (TMDLs) recently approved by the EPA for Upper
Klamath Lake indicate a 40% reduction in phosphorous loading to the lake
is necessary. In order to meet this water quality goal, all anthropogenic
phosphorous loading will have to be eliminated. The proposed curtailment
of irrigation in the Wood River Valley and subsequent reductions in
grazing, coupled with the restoration of the wetlands, is expected to
reduce the anthropogenic phosphorus load to Agency Lake from the Wood
River Valley by 75%. In addition, the restoration of riparian habitat
along the Wood River will reduce water temperatures in the River and at
its point of entry into Agency Lake.
The proposed changes in water and land use detailed above are the easiest,
fastest and most direct way to create a supply of new, clean water in the
Klamath Basin. The Wood River Valley is a prime area for such changes in
water use because on a unit area basis the Valley has great potential to
generate increased flow and reduce phosphorus loading to the lake. More
specifically, the Wood River Valley occupies only 5% of the Upper Klamath
Basin, but supplies 25% of the water and 30% of the phosphorous flowing
into Upper Klamath Lake and supports nearly 50% of the cattle grazed in
3. Land Use and Resources
3.1. Location and Land Use History.
The Wood River Valley is located about 50 miles north of Klamath Falls,
Oregon. The Valley runs north-south, is about 4 miles long by 12 miles
wide and its entire acreage is currently devoted to intense cattle
grazing. At present, about 50,000 steers are pastured in the Valley
throughout the summer, on 48 square miles of irrigated pasture.
The Wood River, Crooked Creek, Sevenmile Creek and Fourmile Creek are the
primary surface water bodies in the Wood River Valley that provide vital
sources of water for the Klamath Basin. These rivers and creeks feed a
sequence of connected water bodies including Agency Lake, Upper Klamath
Lake, the Klamath Irrigation Project and ultimately the Klamath River. The
wetlands and wet meadows of the Wood River Valley are sustained by
drainage ditches and levies and irrigation ditches are used to divert
water from rivers and streams onto pastures. The water rights of ranches
in the Wood River Valley are tied to a range of dates and many water
rights are adjudicated.
The Klamath Indians were the initial inhabitants of the Valley, which was
a part of the former Klamath Reservation. The Klamath Reservation has gone
through a series of changes resulting in the selling of most easement and
water rights to ranchers. At present, two small towns are located in or
near the Wood River Valley, Fort Klamath and Chiloquin.
Cattle grazing in the Valley began in the late in the 19th Century and
continues today on about 15 large ranches. Large-scale ranching by single
landowners with more than 1,000 acres became possible when wetlands in the
Valley were drained by ditches and elaborate flood irrigation systems were
developed for the upland pastures. Pastures require irrigation because
precipitation in the Valley comes mostly in the period November to May.
The period during the summer growing season, from May through October, is
generally dry. Without summer irrigation, the pastures will not support
current grazing practices.
3.2. Current Ranch Activity.
The ranchers who own the land and water in the Wood River Valley are
generally absentee owners who lease grazing rights to cattle owners, who
also live out of state. Cattle are trucked from California, other western
states and Mexico to the Valley in June and are removed in October. The
limited number of ranch owners, the small size of the valley and the
non-resident nature of the landowners makes it possible to convert the
Valley from a ranch-based resource use system to a nature-based resource
system. A significant feature of this proposal is the low economic return
currently generated by this land and the resultant willingness on the part
of most owners to sell. Current gross rental rates for land in the Wood
River Valley range from $70 to 90 per acre. After management, utilities
and taxes are deducted the net income is closer to $40 to 50 per acre for
land, which sells for about $2,600 - $3,000 per acre. The low investment
return (2-3%) may not justify the current use of water in the Valley,
especially when there is great demand for more and cleaner water elsewhere
within the Klamath Basin.
3.3. Natural Features.
The landscape of the Wood River Valley has spectacular beauty. The Valley
sits at the foot of Crater Lake National Park and is surrounded by peaks,
many of which are snowcapped. The forests on slopes surrounding the peaks
are mature and include Lodgepole Pine, other short-leafed pine species and
grand fir. Many riparian and wetland species still persist in the Valley
pastures. Facilitating easy and cost-effective restoration.
The rivers and creeks of the Wood River Valley are fed by water emerging
from springs located in foothills surrounding the Valley, as well as
snowmelt from Crater Lake and the Cascades. The spring water supply is
constant through the year, with water temperatures less than 45o F. The
springs have a natural beauty that is unsurpassed in southern Oregon and
provides unique habitat for many species of plants and animals. Most of
the springs are located off pasture-lands.
3.4. Social Issues.
The towns of Fort Klamath and Chiloquin in the Wood River Valley provide
markets and services for rural residents. The ranch owners typically do
not live in the Valley, but have permanent homes in other locations.
Ranchers will often visit the Valley during the grazing season, but not
during the winter when ranches are staffed by a limited number of hired
hands that maintain the property.
The permanent population of the Wood River Valley is less than 400 people.
The town of Fort Klamath has a population of less than 200 people and has
a café, gas pump and small mercantile. Just outside of the valley, the
town of Chiloquin maintains a population of about 750 people, maintains a
gas station, hardware store, post office and two small mercantiles.
Chiloquin has a small school system. The economies of the two towns are
depressed and economic growth under current land usage is unlikely.
4. Calculation of Water Losses from Flood Irrigation
4.1. Estimating Water Used by Irrigation.
Water that would naturally flow from the Wood River Valley into Agency
Lake is currently being diverted for irrigation of cattle pastures.
Irrigation begins in May, involves large amounts of water by June and is
sustained through September. The irrigation period and growing season
coincide with periods when there is little precipitation in the Klamath
Basin and the need for water by those further downstream is intense. Most
properties in the Valley are flood irrigated and large portions of this
water is lost from the basin by evaporation and transpiration. An estimate
of the total quantity of water lost due to irrigation practices in the
Wood River Valley must be calculated to determine the amount of water that
can be supplied to downstream users through this proposed project. Water
lost in the Valley can be estimated by two independent methods:
Calculating evapotranspiration (ET) of pastures.
Calculating the difference between water entering and leaving the Wood
River Valley, above and below points of diversion.
The results of these two independent methods for calculating the amount of
water lost from the Wood River Valley by irrigation can be compared to
assess the accuracy of the estimates and provide assurance of the quantity
of water that will be made available when irrigation is stopped.
4.2. Using Evapotranspiration to Determine Water Loss.
One method for determining the amount of water lost from pastures as the
result of irrigation is to measure ET. ET is the water lost by evaporation
from soil and plant surfaces and by transpiration from plants in the
pasture (Appendix 1) and is a reliable and frequently used method for
calculating water loss. The ET approach takes into account many of the
variables that are known to affect rates of water loss including soil
qualities, the amount of plant biomass, the field efficiency of pasture
plants and meteorological factors such as temperature, wind and solar
radiation. In fact, ET integrates all of these factors and others, so that
it is not necessary to do an independent accounting of each factor known
to affect water availability and use. In addition, using ET avoids the
need to measure and sum the quantity of water diverted at numerous head
gates and ditches, data that are generally not available or reliable in
the Wood River Valley.
The ET from pasture in the Wood River Drainage and the amount of
irrigation required to meet the ET demand for the May to October growing
season was estimated from well documented values for pasture in the
Klamath Basin. The ET from pasture is about 31 inches and the net
irrigation required is about 29 inches. Consequently, to grow pasture
grass in Valley pastures under current management, 29 inches of irrigation
water are pumped by ET into the air during the growing season. For an acre
of land, envision 29 inches of liquid water spread over the entire acre
and that is the quantity of irrigation water lost by ET each growing
season. Without irrigation, precipitation, soil pore moisture left over
from the rainy season and capillary fringe water from the groundwater
table are capable of supporting some natural pasture growth. Under the
natural condition pasture growth is significantly reduced and large cattle
population cannot be supported by the natural condition. Therefore in
order support current grazing practices, about 29 inches of water, for
each acre of pasture, must be diverted from rivers and creeks during the
May to October growing season. The ET estimate of 29 inches constitutes
about 2.5 acre-feet of water per acre spread over the 48 square miles of
the Valley, or a total water volume of about 80,000 acre-feet, that could
be diverted to downstream users. Since these ET values are based on the
Klamath Falls area (which is slightly drier than the Wood River Valley) a
conservative estimate of irrigation water lost from ET is 60,000 to 80,000
ac-ft per irrigation season.
The ET calculation (Appendix 1) determines the volume of water currently
diverted to maintain pastures and can be used to estimate the new flow
rate of water that can be added to the Upper Klamath Lake if irrigation is
curtailed. The increased flow of water into Agency Lake from the Wood
River Valley, would equal about 200 to 270 cfs. To put this in
perspective, the flow rate of the Wood River during the irrigation season
averages about 200 cfs, so irrigation uses about half the flow of the Wood
River during the summer.
4.3. Monitoring Changes in Wood River Flow Rates to Estimate Water Loss.
A second method for calculating the amount of water that can be added to
the lake by the forbearance of irrigation rights is to compare the volume
of water entering the valley above the irrigation diversion, to the volume
below the irrigation diversions. Data from a variety of sources provides
an estimate of the stream flow in the Wood River Valley during irrigation
and non-irrigation periods and above and below points of diversion.
Historic stream flow records were obtained from USGS publications, from
ODWR, USFS, USBR, The Klamath Tribes and from Graham Matthews and
Associates, who have maintained several stream flow stations in the Wood
River Valley since 1998 (Appendix 2).
Calculations show that about 71,500 acre-feet of stream flow are diverted
in a typical year from the Wood River system and another 15,700 acre-feet
from the Fourmile/Sevenmile systems on the west side of the valley during
the May through September irrigation season. The total of 87,200 acre-feet
diverted from May through September equals 570 acre-feet per day, or 288
The estimate of water lost from irrigation by doing a water balance of
flows for the Wood River Valley is remarkably close to the 200 to 270 cfs
estimated using the ET method above. Estimating water lost from irrigation
by balancing water flows overestimates losses because a proportion of
water used for flood irrigation drains into creeks and rivers to
ultimately reach Agency Lake. This estimation error likely explains the
slight variation between the two methods of water loss calculation.
The close agreement of water used by irrigation provides confidence in the
calculation of water that can be diverted from the Wood River Valley to
Agency Lake and for downstream users. Curtailing irrigation will result in
adding 200 to 270 cfs into Upper Klamath Lake during the summer irrigation
season. The added water is significant to all water users in the Klamath
Basin, will contribute greatly to those seeking to mitigate problems from
low water quantity and quality and equates to 1 ft or more of lake
elevation in Upper Klamath Lake during the growing season.
5. Environmental Restoration in the Wood River Valley
Several ranchers and state and federal agencies have combined efforts to
make improvements in land use in small sections of the Wood River Valley.
In all cases, efforts to restore habitat and biodiversity, such as using
riparian fence to remove cattle from the Wood River Valley, are
successful. Such efforts show that not only will the proposed Project
improve the quantity and quality of water supplied to the downstream
users, but will also help improve the habitat for wildlife, including rare
and endangered species in the Valley. The landowners promoting
conservation are acting independently and, with uncertain funding, are not
able to develop an integrated, comprehensive program for transforming the
Although the detrimental impacts of allowing cattle to have direct access
to streams is well documented, only a very limited portion of the riparian
areas in the Wood River Valley are fenced. Observation of the short
stretches of the Wood River and Crooked Creek that are now protected with
riparian fences to prevent cattle from grazing in or near the streams
indicate without exception, that the exclusion of cattle has resulted in
the return of riparian vegetation, including tree, shrub and wetland
species. Emergence of wetland vegetation and establishment of trees and
shrubs improves habitat for waterfowl, other birds, fish and other
Excluding cattle from streams also results in improved spawning habitat
for red band trout and two species of suckers that are listed as
Endangered Species. The Oregon Department of Fish and Wildlife and the US
Fish and Wildlife Service have identified the Wood River Valley as high
priority habitat for a number of important, rare species including these
fish. The red band rainbow trout is a prime example of a species for which
conservation is a priority. Adults of this trout species live in
Klamath-Agency Lake where they can grow to nearly 20 pounds when not
subjected to poor water quality. Spawning and rearing of juveniles occurs
in the rivers and creeks, of which the Wood River and Crooked Creek are of
principal importance. A comparison of fenced and unfenced sections of
riparian areas shows that degradation of water quality and habitat caused
by cattle grazing in the Valley streams impairs the spawning and rearing
ability of the trout and that riparian vegetation, channel form and
spawning habitat quickly improve when protected from cattle.
6. Restoration in Upper Klamath Lake
Several wetland restoration projects are currently underway in the
Klamath-Agency Lake system. The US Bureau of Land Management has acquired
and is managing the Wood River Ranch for wetland and hunting habitat. In
addition, The Nature Conservancy has acquired and is managing the southern
shores of Agency Lake, an area that includes the Lower Williamson River
Delta Preserve. The US Bureau of Reclamation has acquired the Agency Lake
Ranch and is managing the land as a wetland water storage project around
the periphery of Agency Lake. All three projects are presently constrained
by dikes that separate the wetlands from Agency Lake, thereby hampering
restoration of the ecological function of these lands. Disabling these
dikes will add significant additional water storage in the natural
wetlands that surround Agency Lake. A conservative estimate of water that
could be stored when the dikes are disable is about 45,000 acre-feet.
Increasing the water storage capacity of the Wood River Valley and Agency
Lake provides crucial flexibility for those managing lake levels to supply
water users downstream.
Restoring the hydraulic connectivity between Agency Lake wetlands and
Upper Klamath Lake would provide many benefits that go beyond water
storage. The recovery of wetlands will improve fish habitat and filter
nutrients and sediment from river water thereby improving water quality in
Agency Lake and downstream waters. Breaching the dikes surrounding Agency
Lake will also reduce the current costs of servicing the dikes, pumps and
access roads that are currently needed to operate and maintain the dike
The problems due to over-commitment of water resources in the Klamath
Basin can be addressed by changing water use practices in the Wood River
Valley. The changes proposed include diverting water used for flood
irrigating pastures in the Wood River Valley to downstream users, reducing
cattle grazing to levels that can be sustained without irrigation and
disabling the dikes adjacent Agency Lake. These changes in water use are
the easiest, most efficient means for mitigating one of the most serious
and visible environmental issues in the Pacific Northwest.
Diverting water from the current irrigation uses in the Wood River Valley
will add 60,000 to 80,000 acre-feet, or the volume of at least 1.0 lake
foot of water, to Upper Klamath Lake. In addition, the proposed wetland
restoration and dike removal would add 45,000 acre-feet of storage to the
lake. The additional volume of water will produce a significant increase
for use by farmers, ranchers and government agencies charged with managing
the regions natural resources. Water quality improvements such as the
reduction of phosphorous inputs to Upper Klamath Lake from the Wood River
Valley, will provide additional benefits by reducing harmful algae blooms
that limit the productivity of three endangered fish species and enhancing
recreational use of the lake.
The reduction of cattle grazing to levels sustainable without irrigation
and the fencing of riparian corridors, will improve natural habitats by
allowing stream form and stream beds to recover from cattle intrusion and
by permitting the growth of riparian vegetation. The result will be the
return of seasonal wetlands, improved habitat for fish and aquatic
organisms and cooler water temperatures.
The proposed change in water use practices in the Wood River Valley, will
mean acquiring the water rights owned by 15 ranchers who irrigate in the
48 square miles that constitute the Valley. However, the change in water
use will not remove land from agricultural production and will likely be
welcomed by ranchers who seek financial relief. The change in water use
practices will also have little affect on employment for the sparse
population in the Valley because newly created employment opportunities
are expected to offset lost jobs.
Appendix 1. Assumptions and calculations for ET determinations
Evapotranspiration can be used to estimate the new flow rate of water that
can be added to the Klamath Basin if Valley irrigation is stopped .
Calculations show that the increased flow of water into Agency Lake from
the Wood River and Crooked Creek, if flood irrigation were stopped, would
equal about 230 cfs. To put 230 cfs into perspective, the average flow of
the Wood River is about 190 cfs, so irrigation uses about half the flow of
the Wood River during the summer.
1. The Evapotranspiration (ET) from the Wood River Valley is 31 inches.
2. Seven of the 31 inches of ET come from precipitation and not from
springs feeding the Wood River.
3. The 7 inches of ET from precipitation can not be added to the Wood
River flow and is subtracted from the 31 inches of ET.
4. Irrigation takes place from June 1 - Oct 15 (4.5 months).
5. The Wood River Valley is 48 square miles in area.
1. 31 inches of ET - 7 inches of ET originating from precipitation = 24
inches of ET from the Wood River.
2. 24 inches of ET = 2 feet of liquid water over the landscape.
3. 1 acre = 43,560 square feet x 2 acre feet = 90,000 cubic feet of
4. 4.5 months x 30 days/mo x 24 h/day x 60 min/h x 60 sec/min = 11,664,000
5. 90,000 cubic feet of water/acre divided by 11,664,000 sec = flow of
6. 640 acres/square mile x 48 square miles in the Wood River Valley =
7. 0.00736 cfs/acre x 30,720 acres = 230 cfs.