HomeMy WebLinkAboutWater Board - Minutes - 04/19/1985MINUTES
Water Board
April 19, 1985
Members Present
Norm Evans, Chairman; Henry Caulfield, Vice Chairman; MarvLou Smith, Tom
Sanders, Tom Moore, Bill Elliott, Mort Bittinger, Bernie Cain,
John Scott (alt.), Jim O'Brien (alt.)
Staff Present
Mike Smith, Dennis Bode, Curtis Miller, Ben Alexander, Andy Pireda
nests
Carl Houck of Black & Veatch; David Frick and Sam Bryson of Resource
Consultants
Members Absent
Neil Grigg, David Stewart
Chairman Norm Evans opened the meeting. The following items were
discussed:
Minutes
The minutes for March 22. 1985 were approved.
Chairman Evans welcomed former City Council member Bill Elliott who was
appointed to fill the Water Board vacancy left by Ray Glabach.
Design Report on the Water Treatment Plant
Carl Houck of Black & Veatch Engineers, is the Project Manager of the
design of the 20MGD expansion to the Soldier Canyon Water Treatment Plant.
He presented a brief overview of the status of the project with the aid of
overhead slides. The Project evolved after the initial studies which
began in 1981. These studies basically looked at the Poudre Canyon Plant
and evaluated modifications to upgrade just that facility to make it
capable of providina water from the Poudre drainage system. The estimated
costs to upgrade that facility were in excess of $13,000,000. Considering
that large an expenditure to a plant that was 70-80 years old made the
City and the Consultants question the wisdom of putting that kind of money
into an old facility. Should we not look at other options to achieving
similar coals, they asked. The options that were looked at included:
relocating the Poudre Plant so that it was out of the flood plain to a
lower elevation down the Canyon; possibly a new plant at a location half
way between where the Poudre Plant is and the Soldier Canyon Plant; and
finally, look at combining all the treatment facilities at the Soldier
Canyon Plant. It was decided by the Water Board and the City Council
that the facilities should be provided at the Soldier Canyon site to
replace the Poudre Plant in kind and in capacity, while still providing
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for the flexibility of delivery of water to the expanded Soldier Canyon
Plant from both the Poudre system and the Horsetooth system. Thus, the
current project involves .iust that.
It is a 20MGD expansion at Soldier Canyon to replace, in effect, the 20MG0
of capacity at the current Poudre Plant which will be abandoned once the
expansion is accomplished. It is important to note that there is no
increase in capacity being provided by this effort, but, under the
original premise, if all that was ❑oino to be done was modify and upgrade
the Poudre Plant, there would not have been any increase in capacity.
The Poudre Plant has two transmission mains coming into town which
convey treated water. At Bellvue there is a branch in the lines; the 20"
main goes south and ties into the 15 million qallon reservoir at the
Soldier Canyon Plant. The 27" steel continues on in a southeasterly
direction towards town. The plan of abandoninq the Poudre Plant involves
making use of these two transmission mains, but this time converting them
from treated water to raw water. They will convey raw water to a new 36"
line which will be built and go further south down the western edge of
Claymore Lake. in fact it will be buried under the Lake at the reouest of
the owner. The line will continue all the way down to Treatment Plant No.
2. The reason .this has to be a new segment of line is because the old one
was only 20" and is not sized in capacity to take the full 20MGD.
Tom Sanders asked what material the City is bidding on. We are bidding
on ductile, pre -stressed concrete and steel.
Henry Caulfield commented that we have had trouble with the capacity of
the lines coming down from the plant. What effect does this have on the
capacity of the old line and has that ❑roblem been solved in the process?
Ben Alexander explained that that there was an aluminum hydroxide deposit
before the line was cleaned at the end of 1979 with what is known as a
"pipeline cleaning pia." Even with the best control, by the next summer,
the deposit reoccurred. At that time, the decision was made not to clean
it again until the plant was converted. A cleaning is scheduled for the
first Dart of next week. Since we now have the sodium bicarbonite and
calciuim hydroxide feed at the plant to stabilize the Poudre Plant water,
he continued. that will kee❑ any aluminum that passes the filters in
solution. Hence, the lines should remain clear of the deposit until they
are converted to raw water use. When they are converted to raw water.
they will not develop deposits.
Mr. Houck added that recognizing the lines are Doing to be converted from
treated water to raw water, what about the customers who are on the
present treated water line? In the canyon there are five customers who
have been on the line for a long time. About the only way to solve the
problem is to dig wells and to hook them to the wells which will cost the
City from $30-40.000. The 27" line will no longer have treated water, so
we have a number of customers who will have to be converted over. There
are various ways that this will happen. Curt Miller will tall: about that
later.
After the expansion all our water will be brought to one plant for
treatment. When it is treated, it will be out into the distribution
system from one single location, so it will be necessary to increase the
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size and .number of lines coming out of the Soldier Canyon Plant. Through
a series of investigations, what has evolved is a plan to take a 48" line
out of Soldier Canyon all the way down to where the present 27" steel
line is that comes down from the Canyon. The water will flow the way it
is normallly distributed into town. What about the other 27" steel line?
The plan there is essentially in the same right-of-way that the 48" line
will be built. A 24" high pressure line will also be built on the same
gradient of the foothills pumping station. We will take discharge from
the foothills station and tie the line into the 27" on the upstream side
and pressurize the water all the way back up to Bellvue. This will
improve the water service for the whole northwest quadrant.
Curt Miller nave a brief background on the placement of the pipelines.
Staff has spent a lot of time talkinq with people in the areas where the
Pipeline is to be constructed. He pointed out on the map the current
proposed route, indicating the alternatives that were discussed.
Mr. Miller related that there will be a 30" line going to the
Anheuser-Busch site for their water supply.
Mr. Miller answered some questions from the Board. He went on to explain
the arrangements with the West Fort Collins Water District and the Bellvue
Water Association. The people in the area north of Bellvue riqht along
the pipeline have had water service from those lines that are now going to
be converted to raw water. The City also serves the town of Bellvue
through a single meter. It turns out that West Fort Collins, whom the
City sells water to on a wholesale basis, serves mast of that area and
they would be able to serve those eight customers. We will make some
conversions necessary to do that. Ultimately, the City would like to
chance the boundaries so that everything north and west of Bingham Hill
would be served by West Fort Collins, and everythinq below that, aqreed to
by both sides would be served by the City. This arrangement would be
easier for both the City and West Fort Collins.
Next Carl Houck talked about some of the details of the facilites at the
Poudre Canyon Plant. The diversion dam will be rebuilt and some work will
be done on the spillway in an attempt to improve its capability to pass
the 100 Year flood without any serious damage to the structure. They are
proposing to build a new pre -sedimentation facility on the south side of
the plant which would not be subject to flooding. The sand will be
sluiced and put back into the river.
The question was raised as to why they weren't desionino the dam to
withstand a S00 year flood. Carl Houck explained that if you net up to a
200,000 second foot discharge, in his opinion, there isn't any we,,,
physically in the narrow confines of the canyon to protect it. He added
that you have more of a potential to wash out the buried pipeline which
crosses the river several times, than to damage this structure. Ben
Alexander pointed out that the State Health Debt. guidelines require that
there be protection for the 100 year flood.
Tom Sanders stressed that we still have this area of vulnerability which
we had hoped to avoid when we decided to abandon Plant No. 1. Carl Houck
explained that we still have the backup of raw water supply from
Horsetooth. Curt Miller added that if the pipeline went out, while it was
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being repaired, we would be able to treat additional Horsetooth water to
make up for it with our treatment capacity. Therefore, the City would not
be put in jeopardy in terms of its service requirements.
Next, Mr. Houck talked about the intake structure and answered a number
of questions including one about a potential "fishway" or fish ladder near
the structure as a "public relations" effort.
Tom Sanders asked if we have decided if the site will indeed be abandoned.
Mr. Houck said ves, abandoned from the treatment standpoint. Dr. Sanders
doesn't think that is such a gaod idea to completely abandon the old plant
for treatment in the event of a need for it in the future.
Henry Caulfield confirmed that the Water Board did decide to completely
abandon the plant for treatment. Whether that is acceptable or not can
still be discussed. He added that, in the future, when we have a joint
faciity, it would be down river. There was no consideration to keeninq
the ❑resent site because of the threat of flooding.
Mr. Houck continued with his presentation by explaininq the
pre -sedimentation process. Jim O'Brien asked if we have the same
capability at the plant currently• If so what sort of concentrations and
tons per year of sediment or sand are we aettinq out of it? Mr. Houck
said there is a pre -sedimentation channel to which the flow comes and lets
the sediment drop. There is a sand sluice that removes some of it. There
is also a long section that the lighter materials go into and settle out.
About every two Years it is necessary to clean that out. The size of the
deposit is about 150 feet Iona -- maybe a trapezoid that has 1S ft. at the
base and mounds up to S or 6 feet in height. This is approximately the
quantity of material we are talkinq about, he added.
Curt Miller explained that the irrigators always sluice the sand back into
the river too. Ben Alexander added that at the time when the bed load in
the river is moving, the discharge is continuous, so that it doesn't pile
Up. Norm Evans asked if there is any discharge permit required for that.
The City is working with the State Health Dept. and the State Engineer on
that issue now.
134-11 Elliott asked about the structure from a security standpoint. Mr.
Houck and Mr. Miller both said that they anticipate few problems, and that
there will be remote monitoring devices; this includes trubidity and
organics monitoring too.
At treatment Plant No. 2, there currently exists a S4" line comina into
the plant using Horsetooth water at about 200 feet of head when the
reservoir is full. It goes throuqh a pressure reducing vault and on into
the plant. We are investigatinq the potential to take that Horsetooth
water, put it throuah some parallel turbines to be able to generate power.
In addition, we would take the Poudre water through the turbines also.
The interesting thing is that the elevation on the dam at the Poudre is
the same elevation as the water surface at Horsetooth. Under static
conditions, there is the same static head on the Paudre supply as there is
with the Horsetooth supply. That means at low flows in the Poudre system,
there is still significant head which must be broken at Plant No. 2 in
order to take the water into the treatment plant. Instead of just
breaking that head through a pressure reducing valve, we are investigating
whether we can, in addition, generate power. It is too early to give the
Board a report on the actual development of that.
Tom Sanders asked if the City owns the rights to do that. Mr. Houck said
we are getting into an area where there are sensitive negotiations
involved. Perhaps in a couple of months, he can return and give the Board
a report.
A question was asked earlier about treatment plant redundancy. Mr. Houck
explained that the new treatment facility will be a totally separate third
train. Now, the treatment facility consists of two trains which are
basically independent. The third train with a capacity of 20MGD, will be
dedicated mostly to the treatment of Paudre water, but into which
Horsetooth water could be added. There will be a ma.ior construction of
sludge handling and back wash holding facilities on the land the City
owns. These ponds will not be very visible from the road.
Henry Caulfield asked about additional treated water storaqe. There are
30 million gallons of treated water storage now, Curt Miller replied. He
added that the City is manifoldinq the transmission lines from those
treated water reservoirs in the event that if it proves to be cost
effective, we have the location to build two more reservoirs north of
there at 15 million gallons each.
Jim O'Brien asked if we are planning any expansion of the pipelines. Any
expansion that will occur in the future will automatically involve the
Soldier Canyon Plant as a key element of whatever water distribution
network is set up, of either a regional basis or for the City. There is a
large source of Horsetooth water and an additional source of Poudre water
there.
To conclude his remarks, Mr. Houck Pave a preliminary estimate of cost.
The numbers have changed since the value engineerinq review. The cost
estimate is $18,000,000.
Report on the Drouaht Study
Dennis Bode related that the Drought Study has been going an for about a
year and has been a cooperative effort between Resource Consultants and
City staff. About six months ago the Consultant and Mr. Bode reviewed the
progress for the Water Board. Today Resource Consultants and Dennis Bode
will bring the Board up to date as we enter the final stages of the study.
Dave Frick will talk about some of the droughts and the flow data. Dennis
Bode will review some of the modeling work that staff did, and finally.
Sam Bryson will get into some of the drought strategies that were looked
at.
A draft copy of the summary report "Droughts and their Effect on the Water
Supplies of Fort Collins," was qiven to Board members prior to the
meeting. Dave Frick explained that the study involved three major tasks:
1) Determination of prolonged drought characteristics of the Cache La
Poudre River Basin. 2) Evaluation of drought effects on the City's water
supply, for both present and future conditions, 3) Identification and
analysis of various water supply strategies that could be adopted by the
City for dealinq with e/,treme droughts in the future.
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To date drought characteristics for the basin have been developed
including the estimate of waters that would be imported to the basin
through the CBT system, as well as both the Laramie Poudre Tunnel and the
Grand River Ditch System. Dennis Bode and Andy Pineda have been work.in❑
on the modeling of the whole river basin and also the Citv's water supply
to determine what the effect of the droughts would be on the City's
system. Finally, the Consultants are in the midst of developing some
strategies to help ensure adequate water supplies for the City, both now
and in the future. They are hoping to produce the final report about the
first of June.
Mr. Frick explained how they determined the drought characteristics of the
basin. They first took the data from the virgin river flows for the
Poudre. Big Thompson, the North Fork of the Michigan, the Larimie River
and the Colorado River in order to get a regional approach which affects
the imported water supplies to the City. They extrapolated what records
they had on partial data and made a complete data set and looked at the
statistical characteristics and developed a stochastic model. The purpose
being to generate better estimates of 1-in-100 and 1-in-500 droughts.
Next, they took the stochastic model and generated 500 year segments of
data and analyzed those for the particular drought characteristics. From
those records they selected drought periods which they felt were
representative of the various frequencies of droughts and used those for
modeling the City's water system performance throuqh those droughts. And
finally, they made some estimates of imported water supplies and also did
an analysis to see if the stochastic model generally matched some lonq
term tree rinq data obtained in the vicinity of the basin. They looked at
the cross correlation of the relationship between Poudre flows as compared
with the other basins. This led to the question of how reliable the Big
Thompson supply is during a prolonged drought as well as some of the other
imported water supplies.
Droughts were defined as periods when the annual flows of the Poudr•e
River were below the average mean flow. Three different ways to express a
drouqht are: 1) the length in years (run length), 2) run sum -- total
deficit from mean flow that occurs during the drought, 3) run intensity
which is the average deficit that occurs during the drought period. For
direct flow decrees the short duration droughts with a high intensity
are much more crucial than a long term less intense drought even though
the total deficit might be more. For storage conditions a lonq term
drought is more crucial. Not only did they have to look at what a drought
is, they had to define it in terms of the three areas .mentioned above.
Their next task was to develop a stochastic model and generate 50,000
years worth of data in 500 year segments. A comparison of the
generated data versus the historic data showed that the historic means and
standard deviations closely matched the historic data.
Next, they did an analysis of the generated data where they divided the
data into 20, 50, 100, and 600 year segments and defined the worst drouqht
in each of those segments, and averaged those to come up with some average
drouqht characteristics.
Mr. Frick showed a slide of the four representative drouqhts that they
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selected. These are the drouqhts that were used in modeling the City's
water supplies to see what the total yield would be. To verify
their estimates they looked into some tree ring data. They compared the
tree rinq information with the river flows and they matched up quite
well. After that they compared the tree rings to the qenerated data. It
appears there are no lonq term trends or cyclic variations in the data
from looking at the tree rings. They went one step further and qenerated
a stream flow based on the fairly weak correlation they had between them.
Essentially, lookinq at drought characteristics of the generated flow with
the tree ring data, they found the characteristics were very similar.
Thus, they felt this verified that their stochastic model was pretty good.
Finally, they came up with estimates of imported water flows for the whole
500 years. This resulted in an estimate of the total basin supplies.
They then disaogreoated the annual flows to monthly flows so staff could
take 30 year segments around each drouaht period and model that throuqh
the City's water supply system. Henry Caulfield asked if they found that
the droughts occur simultaneously on both the eastern and western slop.=_s.
Climatoloqists, he said, indicate that they vary significantly. Dennis
Bode said that it would be highly unlikely that there would be, for
example, a high flow on the Colorado River and a very low flow on the
Poudre River in the same year.
Dennis Bode continued the presentation by sayinq that all of this
information gives the City a good basis for planning. There are two
levels of planninq, one directed towards the normal supply that we would
acquire and have on hand and the other area is the emerqency measures we
miqht need to take during a very severe drought. In general, he said, we
don't see immediate policy measures that are needed right away, but the
information gives us some good tools for future planninq,
Mr. Bode showed the schematic of the model on which he and Andy Pineda
have spent considerable time. They used the inflow data that Resource
Consultants provided. Represented on the schematic are the direct flow
riahts, the Michigan Ditch System, the Monroe Canal as an exchange point,
the Southside Ditches, a future reservoir labeled as Rockwell Reservoir,
Horsetooth Reservoir, and a plains reservoir. This is all driven by the
demand from the City of Fort Collins. This model was developed with the
aid of CSU, primarily Dr. Labadie. The main thinq that staff was after
was to look at the difference that the various droughts would have on our
supply system, taking into account both the present and the future.
Staff looked at five scenarios: one in 1985, the system as it is today;
2 in 1995 for a 10 years down the road look -- i in which the primary
supply was the addition of North Poudre and CBT units, and one scenario
where some storage was added; 2 in SO years with the same emphasis --
CBT/North Poudre and 30,000 AF of additional storage.
They used a projected demand based on estimated population growth and they
assumed a slighly declining per capita use for that demand. In future
runs for planning purposes they can vary those demands so they can get
into predictinq the effect different demands will have on the supply.
Next, Mr. Bode explained table 2, the Summary Results of Operational Runs
which was in the report. He clarified the phrase safe average demand
since there was some confusion about that. It is the same as safe averaqe
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yield which had been used before, and is defined as the maximum averaqe
annual demand that could be met for treated water in the City. The safe
average demands that could be met by the City's water supply systam are
relatively hiqh compared to present demand levels. It is estimated that
the average demand for treated water in the City of Fort Collins is
currently around 19,000 ac-ft per year (demands for 1995 assuminq average
precipitation). From table 2, the safe average demand for treated water
that could be met during a very extreme 1-in-500 drought is 22,000
ac-ft/yr (26,000 ac-ft/vr for a 1-in-100 drought). Hence, the existinq
water supply appears to be adequate for present demand levels, capable of
withstanding even extreme droughts.
There was a question about use of the wordmaximum with averaqe. Mr,
Bode explained that the reason we use maximumis if we have an averaqe
demand level of 19.000 a-f, we still have surplus in the system and we
could put a higher demand an the system we have today --up to the point
where we would .just meet the most critical year without gattinq into a
shortage that year. The reason we use maximum, he stressed, is to say we
can increase the demand level up to the point where we can ,just meet those
demands with the supply that is on hand.
Mr. Bode went to another chart showing a 30 year period with a 3 year
drought that corresponds to the 1-in-20 drought. The chart also showed
demands for individual years. They concluded that the 1-in-20 safe
averaqe demand is the maximum average annual demand that we can place on
this system. Once the number is established (remember that the supply is
fixed for 1985), they select the 30 year period for the 1-in-100 drought
and run it throuqh using the same demand to realize the impact of a more
severe drought. In the early Years of such a drought, demands could be
met. In the later years there would be shortages. If we wanted to meet a
1-in-500 drought we could only meet an average annual demand of 22.000
ac-ft. In a dry year the demand is goino to be higher than the average
annual demand. Assuming the supply is designed for the 1-in-20 drought
there is no deficit; it meets those demands. For the more severe droughts
deficits were shown. The chart shows the most severe year and the
percentage of the demand that was met as well as the cumulative deficit
which includes all years of shortages in that particular drought. The
staff went through the same procedure for all the supply scenarios which
gave them a good look at both the safe average demand and also the impact
if you were designinq for .just a 1-in-20 drought. As was mentioned
previously, the study showed that a 1-in-500 drought could be met today.
For the future analysis, as explained earlier, enouqh supply was assumed
to meet the 1-in-20 drought for a demand 10 years into the future. The
main objective of this analysis was to determine the relative effect of
drouahts on supplies for different drouqht severities. With the assumed
supply, simulation runs were made to 1) determine the safe annual demand
for each of the four types of drouqhts and 2) determine the impact of the
more severe droughts by holdinq the demands constant for each and
evaluatinq the resultinq shortages. Next, Mr. Bode explained the chart on
p. 11 of the report --Fioure 3 Demand -Drought Relationships. They used
the Years 1985. 1995 and 2035. They concluded that as we become involved
in the longer droughts, the simulation showed that CBT may become
depleted. Also, storage capacity built into the system helps during a
drought, but if the drouqht lasts long enough, the storage iz eventuallv
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depleted with little chance of refilling. When considerinq possible
sources for future supplies, a primary consideration is the cost of
acquirinq or developing water rights, stock or new reservoirs.
In conclusion, two levels of planning are needed to meet the water demands
of the future. The first level is the development of the criteria and
policies for a permanent supply of water. Present policies may
eventually need to be ad.iusted to provide a pre -determined level of
safety. The second level is the development of emergency measures needed
in the event that the permanent supplies either fall behind schedule or a
more severe drought than planned for occurs.
Sam Bryson discussed Drought Desiqn Criteria and strateqies. He beqan by
saying that the basic water supply strategv in dealing with droughts is to
try to maintain an adequate water supply that Pets you through most
droughts but not every one. No water supply plan is designed for 100%
reliability for any kind of drought. Their preliminary recommendation is
to design for a 1-in-100 drought and use emergency measures for the more
critical periods. The operation studies that Dennis Bode and Andy Pineda
did with the selected drouqhts revealed that the Fort Collins system is
currently adequate for a 1-in-500 drought. Furthermore, with the water
acquisition policies continued, and qrowth as it is beinq projected, the
system will remain adequate for a 1-in-S00 year drought for a few years
into the future. However, they have not made runs to determine how long
the system will remain adeauate for a 1-in-500 year drought. There is a
lot of safety factor in the present system. The consultants, therefore,
do not see much urpencv to develop emergency plans for dealinq with
droughts more extreme than the 1-in--500 case, and also, there is not much
need to change water acquistion policies to try to come up with a more
reliable system. These were the short term conclusions.
The Iona term conclusions were that, eventually, the system will fall in
line with a 1-in-100 drought. When that happens, several options could
be implemented to keep it at a 1-in-100 level. They might be to: 1)
Revise the water acquisition policy, no longer aettinq direct flow riqhts
but goina for storage rights: 2) Reduce water usage: 3) Improve
facilities. The consultants have not made recommendations on any of these
options.
When the system is only sized for the 1-in-100 drought, you no longer
have the large safety factor. You could be hit with a 1-in-S00 drought.
There would be a greater need at that time to have a set of emergencv
plans ready which miqht include:
1. The City should enter into agreements with various irrigation
reservoir companies allowinq the storage, in below-averaqe years, of
any excess water owned by the City
2. Plans should be developed that, in a critical year, would
significantly reduce water usage through voluntary or mandatory
restrictions.
3. Agreements should be prepared with various users of agricultural
water allowinq rental of the water in emergency situations whenever
conservation measures appear to be inadequate.
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Henry Caulfield suggested that when this report is finalized and made
public, that these emergency measures by listed as options without any
specific recommendations. There are relative costs involved about which
we know little, he added. There is also the question of storage
because there are alternatives there too. The Water Board does not want
it construed that they endorse any of those measures.
Dennis Bode said that the final report will be compiled in a few weeks.
Norm Evans commended the work that has been done on this report. MaryLcu
Smith added that from her viewpoint, this was some of the most concrete
data that they have received as a Water Board to help them make decisions.
Norm Evans announced that the Water Board has been asked to hear the
Anheuser-Busch update for the next meeting. Dr. Evans asked if the Board
would be willinq to meet at 9 00 in the morninq on Friday. May 17, a more
convenient time for the A-8 representatives. Most of the members
present indicated that they would be able to come at that time.
Tom Sanders asked if the City has purchased the CST shares yet. Dennis
Bode said that it has been advertised and the closinq date is April 2S.
At that time the City will have received all the offers and will evaluate
them, and select one for purchase.
Tom Sanders reiterated his earlier desire to investiqate the hydro power
rights for the new treatment facility.
MaryLou Smith announced that the Bylaws committee met and has indicated
some areas that the Board needs to look at. She distributead these
sugpested changes to the Board for their review and comments. Bylaws
revisions will be discussed at a later meeting.
Dennis Bode distributed the final copy of the Water Rate Study.
Jim O'Brien asked what happened to the resolution on election of Water
Conservancy District Board members. He was told that the City Council
passed the resolution in the form that council member Jerry Horak had
proposed.
Since there was no further business, the meeting was adjourned at S:3E.
Water Board Secretary