ASPEN CITY COUNCIL WORK SESSION
MEMORANDUM
TO:

Mayor and City Council

FROM:

Margaret Medellin, Utilities Portfolio Manager

THRU:

Scott Miller, Director of Public Works;
Dave Hornbacher, Director, Utilities and Environmental Initiatives;

DATE OF MEMO:

July 7, 2017

MEETING DATE:

July 11, 2017

RE:

Risk Assessment of Aspen’s Water System - Work Session

SUMMARY: On October 10, 2016, Council passed Resolution #141, Series of 2016 directing staff to
implement certain water management measures to improve resiliency against future climate change
impacts and other system changes while continuing efforts to maintain diligence for two conditional water
storage rights on Castle and Maroon Creeks. Included in this Resolution was direction to further refine
Aspen’s future water supply and demand. To this end, Aspen contracted with Headwaters Corporation to
perform a risk assessment of Aspen’s Water System, now and through 2065. During the July 11th work
session, staff and its consultant will provide Council a status report on current findings and then will ask
Council for some direction on specific decision points.
Headwaters Corporation is performing a risk analysis of Aspen’s Water System to determine the City’s
level of risk for experiencing shortages in its water system through 2065. The goals of this analysis
include the following items:
1.
2.
3.
4.

Identify key variables that drive the system’s supply and demand projections
Calculate the probable range of water shortages now through 2065
Determine actions that can minimize short- and long-term uncertainty with supply and demand
Consider the probable, worst-case scenario(s) for water shortage for year 2065

When considering water needs fifty years into the future, all communities must grapple with uncertainties
and can only make projections based on the best information available today. The goal is to work with a
vision of the future that Council can agree on and to ascertain Council’s risk tolerance based on the best
data we have.
PREVIOUS COUNCIL ACTION: At the March 20, 2017 Council work session, Dr. George Oamek,
consultant with Headwaters Corporation, was introduced to City Council. Dr. Oamek discussed the risk
analysis that he is conducting for the City on its water supply and demand projections. At the July 11th
work session, Dr. Oamek will provide Council with an update of his findings and seek Council input on
some variables so the report can be updated for the next work session.

 DISCUSSION: The Risk Assessment of Aspen’s Water System report reveals our areas of vulnerability
in the system and identifies areas of improvement to reduce uncertainties in the future. This report is the
basis for today’s discussion, which is aimed toward a specific goal: What’s the best decision we can make
with regard to water storage needs through 2065 given that there are some uncertainties in the data. To
reach this goal, staff will discuss with Council the areas identified in the Risk Assessment that need
immediate refinement based on current legal challenges and the desire to reach a settlement with opposers
in our conditional water storage rights court case. In a future work session staff will discuss other areas of
refinement that are not imminently related to the lawsuit. This is the first of many discussions on
reaching a decision on water storage needs. Integral to this conversation is both a look at supply and
demand.
Although there are levels of uncertainty in the data on supply and demand, one thing is clear: during peak
summer use, Aspen has less than a day of raw water storage. This means that the City of Aspen would
have difficulty getting water to customers’ taps after a day’s time if for any reason Castle and Maroon
stop flowing, for instance due to wildfire or avalanche. This lack of storage is also significant during dry
periods when the flow into Aspen’s system does not meet the demand of its customers.
For the purposes of this discussion and long-range planning it is important to consider “worst-case
scenario” as the situation to plan for. Defining the worst-case scenario is integral to our discussion on
what constitutes a “water shortage”. Worst case scenario planning is essential to determine how Aspen’s
Integrated Water System can be expected to perform during the most extreme, yet probable conditions.
Aspen has been collecting data on its water system, both supply and demand, since the water department
was established. For this analysis, historic records were reviewed and, as appropriate, incorporated into
the risk analysis.
Results of this analysis are meant to frame the level of risk that is appropriate for the City’s long-range
water planning. This analysis does not intend to prescribe how the City should develop, but rather to
inform current leaders and provide future leaders the ability to meet an uncertain, yet probable, future. In
addition, this effort is not intended to describe the best alternatives for meeting future needs or best
management practices to reduce this vulnerability.
Areas for Immediate Refinement (Variables)
1. Future Expansion of the Water Service Area – Should Aspen consider expansion of the water
service boundary?
2. Definition of Shortage – What level of instream flow and municipal water supply does the City
want to maintain?
Questions
•

•
•

Should the 2% growth caps be applied uniformly across all types of residential and commercial
land uses, or should different rates of growth for different types of residential and commercial
properties be assumed?
What types of land use should be assumed to grow faster, or slower, compared to others?
Is there a range of land use growth rates that should be considered in this effort?

 Future Expansion of the Water Service Area
In the last few years, the City has received annexation requests for county parcels located adjacent to the
City boundary. Additionally, the Water Department receives service requests from properties outside of
the City boundary, where Aspen does not have planning jurisdiction. Staff recommends a specific policy
be created to assist in the evaluation of future annexation and service requests. In addition, Aspen has an
existing annexation plan, but it focuses on the legal process for annexation, rather than broader policies
that should guide decisions on annexation.
To determine the worst-case scenario using the best data currently available, staff would like to discuss
the following with Council:
Question
•

Is there an upper limit to expansion of the water service area that should be used in this analysis?

Definition of Shortage
The definition of a water shortage has traditionally been defined as periods when flows in Castle and
Maroon Creeks are insufficient to meet Aspen’s baseline municipal demand without reducing minimum
instream flows. Changing the definition of a water shortage would change the level and occurrence of
shortages.
Of immediate concern for determining the worst-case scenario, staff would like to discuss:
Questions
•
•
•
•

Does Council want to revisit its policy on protecting instream flows?
Would the City be willing to chronically reduce instream flows to meet potable demands?
How many hours/days or raw water storage is necessary for Aspen’s risk tolerance?
What does a worst-case scenario mean to you?

COUNCIL DIRECTION REQUESTED: During the work session, Council is asked to provide
direction regarding:
• Answer questions posed regarding three areas of refinement
• Begin to assess the level of risk appropriate for Aspen’s Water System
ENVIRONMENTAL IMPACTS: The City is committed to reducing its footprint (carbon and water)
and fighting climate change, but even with this effort and action the City recognizes that it is best practice
to plan for a future that looks very different than today. Incorporating risk into the City’s demand and
supply projections is necessary to ensure the resiliency of its water system.
BUDGET IMPACT: Funds to support the work associated with Aspen’s Water Future was included in
the recently adopted spring supplemental budget.

 CITY MANAGER COMMENTS:
ATTACHMENTS: Attachment A – Risk Assessment of Aspen’s Water System Memo, Headwaters
Corporation