Hurst Creek Municipal Utility District was created by the Texas Water Commission in 1979 to provide water, sewer and drainage services to approximately 700 acres in western Travis County, Texas. As a political subdivision of the State of Texas, the District is retail, non-profit public utility with the rights, powers and responsibilities as outlined in Chapter 54 of the Texas Water Code. In 2003 the Texas Legislature mandated the Texas Commission on Environmental Quality (TCEQ), the successor agency to the Texas Water Commission, to adopt rules requiring all public water utilities appropriating more than 1,000 acre feet of surface water to develop water conservation plans with five and ten year goals. This document examines the District’s water
usage for the past five years and proposes five and ten year
goals for conservation.
Hurst Creek MUD’s primary service area is a residential subdivision, The Hills of Lakeway, originally platted in 1979 in the City of Austin’s extraterritorial jurisdiction. The subdivision consists of approximately 1,042 single family lots, 158 condo lots, and a small commercial tract fronting Lohman’s Crossing Road. The commercial tract is within the City of Lakeway and contains an office complex, an assisted living center and a skilled nursing center which is currently under construction. A general location map and a detailed map of the water distribution system are attached as Appendix Items 1 and 2. Since the creation of the District, a municipality, the Village of The Hills, has been incorporated within the original District boundaries. Additionally, The District has annexed some 34 acres to include the Emmaus Catholic Church and adjacent grounds. The residential portion of the District is nearing build out, with only 95 vacant single family home (SFH) lots and 3 vacant condo lots remaining. The majority of the existing homes are moderately large, with the average appraised value of a homestead at $357,193 in 2004, the most recent year available. Most homes are heavily landscaped and lawn sprinkler irrigation systems are required by the Property Owner Association Architectural Rules. There are five condominium regimes within the District, with an average of 15 units each. Appendix 3 lists the various connection types. Most streets within the District are privately owned by the Property Owners Association, and access is restricted by a system of computer-controlled traffic gates; only residents and their guests are capable of free ingress. A private security firm oversees the manned gate.
The District purchases raw water from Lake Travis pursuant to a Water Sale Contract and Conveyance Agreement. The raw water is pumped through an 11,000 foot pipeline and treated by the District’s two water treatment plants, each with a capacity of 1 MGD. Treated water is stored in two ground storage tanks of 150,000 gallons each, and a 500,000 gallon elevated tower. A network of water mains ranging in size from 16” to 6”
deliver treated water to the District’s customers. All connections are metered, with meter sizes ranging from ¾” to 2”. The District monitors meter age carefully, and regularly replaces meters after they register more than 3 million gallons, or after ten years of service. The system is financed primarily via ad valorem property taxes levied on all property within the District, and to a lesser extent, from service revenues. All facilities were designed by registered professional engineers, approved by the appropriate State agencies, and maintained by licensed operators. Hurst Creek MUD received recognition by the US Environmental Protection Agency as the best managed and operated water utility of its size in the five state EPA Region 6.
Usage patterns for the previous five years are shown on Appendix 4. A close examination of these patterns reveals the following: Monthly and daily per connection use is high, averaging 20,504 gallons per month, or 683 gallons per day over the five year period. There is no consistent pattern of rising or falling usage over the five year period. Peak usage occurred in 2000, with 25,827 gallons per month, and was lowest in 2004, with 18,359 gallons. The most likely explanation of this phenomena is that the majority of water usage is for lawn irrigation, which is dependent on rainfall trends. An analysis of the summer to winter usage ratio in a representative year indicates that summer use is about 2.6 times the volume used in the winter. Water accountability is excellent, ranging from 96.8%
to 88.2%, with an average accountability of 93.9%. This
high accountability is the result of a wholesale change-out
of all service lines in the system several years ago, an
active water meter replacement program, and a diligent
meter reading program.
As the District is nearly built-out, usage patterns are anticipated to remain similar to the previous five years. The District’s water sale contract, treatment and distribution systems were designed to accommodate relatively high per capita water use, and the upscale economic character of the service area is anticipated to continue. Because a major portion of the District’s funding is from ad valorem taxes, it will be politically difficult to affect usage patterns by raising utility rates high enough to discourage lawn watering.
Due to the legislative ban on wastewater discharges in the Highland Lakes region, golf course irrigation with wastewater effluent goes hand-in-glove with operation of a public water system. The District has a number of contracts with the Hills Golf Course allowing for the disposal of treated wastewater effluent. Conversely, storage of wastewater effluent is essential for operation of the course during the hot, dry summer months, when area lakes are low, drinking water demand is high and the LCRA’s water conservation plans may curtail the use of scarce lake water on golf courses. Hurst Creek MUD’s irrigation infrastructure includes a 500,000 gallon per day wastewater treatment plant, a 210,000 gallon surge tank, a 12” diameter effluent force main, a 50 million gallon effluent holding pond, and a sophisticated computer-controlled pumping and valving system. The actual irrigation distribution system belongs to the owner of the golf course. The irrigation system provides for the application to the golf course of effluent stored in the 50 MG pond, or alternately, water from Hurst Creek may be used. However, state law forbids the introduction of the effluent into the creek. Effluent and creek irrigation volumes are separately accounted. The contracts between the District and golf course stipulate that the District will pump water from Lake Travis, as part of its water sale contract with the LCRA, to maintain water levels in Hurst Creek. The golf course may take suction from the creek, but must pay the District for the water withdrawn; in turn, the District must pay the LCRA for creek water used. In practice, the golf course requires up to 800,000 gallons per day during hot, dry summer days, but virtually none at all during the winter. Therefore, it is essential that the District and the golf course work closely together to manage effluent pond levels; the pond cannot be allowed to exceed its rated capacity of 50 MG and it is equally undesirable to empty the pond before the end of summer, and run short of irrigation supply. Effluent irrigation typically takes place at night, when the course is closed to play, and large volumes are applied – up to 1,800 gallons per minute –by a network of sprinkler stations spaced throughout the course. To operate properly, an irrigation distribution system must be kept pressurized at all times, even when sprinkling is not taking place. Additionally, landscape maintenance personnel use irrigation water during the day, but not in sufficient volumes to justify running the District’s 250 hp effluent pumps. Because the golf course irrigation system is kept pressurized with water from Hurst Creek on a continuing basis, and effluent from the pond is supplied only during major irrigation cycles, there is an appreciable quantity of creek water used on the golf course in between the major irrigation events. This creek water must be replenished with Lake Travis water, purchased by the District from the LCRA. This lake water usage represents the most feasible opportunity for water conservation efforts. In 2005 this total was 36.02 MG. Replacement of this 36 MG of lake water with effluent is the primary goal for the District’s conservation efforts.
Golf course irrigation demand, like drinking water, is highly weather dependent. A roughly constant flow of wastewater must be stored and apportioned onto the golf course so that the storage pond neither overflows nor goes dry. Over the past twenty years golf course irrigation demand has ranged from about 39 MG during a wet year to 161 MG during a dry year. Average annual use appears to be around 97 MG. Refer to Appendix 5 for historical usage.
As 100% of all wastewater effluent produced by the District must be irrigated on the golf course or adjacent landscaping, effluent disposal must be the guiding principle of reuse. Current wastewater production is around 200,000 gallons per day, and slightly more than this volume will be produced at full build-out. Additionally, the District is contractually obligated to store and dispose of a maximum of 100,000 gallons per day of treated effluent from WCID#17’s wastewater treatment plant. Total effluent production will exceed the average annual golf course irrigation demand of 264,527 gallons per day, and it is obvious that additional irrigable areas will be required in the future. However, in actuality, averages are somewhat meaningless. In a dry year there will not be enough effluent and we will require water from Lake Travis to meet golf course demand; in a wet year we will be urging the golf course to irrigate in excess of their actual needs, to legally dispose of the necessary volume of effluent.
As described above, the District’s service area is composed of relatively large, affluent homes with extensive landscaping. In 2002 the District implemented an increasing block rate structure, wherein larger volumes of water are billed at a higher rate. There was no noticeable effect on overall water demand; the customers merely paid more and kept on watering their expensively-landscaped lawns. The District periodically sends out flyers and posts notices on the Village website requesting voluntary watering scheduling during dry summer months. This scheduling has had the effect of leveling out the peak demand period during daily lawn irrigation, but has had little effect on overall water use. More successful have been the changes made in effluent reuse. Construction of the 50 MG effluent holding pond has reduced the usage of Lake Travis water for golf course irrigation, and refinements to effluent reuse practices appear to hold the most promise at achieving additional conservation.
Certain changes in the irrigation infrastructure will
have beneficial effects on reducing the volumes of Lake
Travis water required for the golf course. These changes
include modifying the pumping facilities at the effluent
holding pond along with the computer control system to
allow constant maintenance of irrigation system pressure
with effluent, instead of creek/lake water. Certain other
modifications will be required Improvements in conservation of treated water will be more difficult to achieve and will result in relatively minor savings in water use. Five year Goal – replace with effluent 10% of the lake water pumped to Hurst Creek for golf course irrigation. Using the numbers for 2005, for example, this effort would have conserved about 3.6 million gallons of Lake Travis water. On the treated water side, it would be difficult to improve on water accountability (which averages over 90% accountability for the past five years), so our goal is to maintain this high level of accountability. Regarding per capita water use, the District proposes to reduce by 5% the annual use per connection, primarily via customer education and increasing the rates for higher levels of consumption. Ten Year Goal – replace with effluent 25% of the lake water pumped to Hurst Creek for golf course irrigation. Based on 2005 numbers, this would conserve about 9 million gallons of Lake Travis water annually. Regarding treated water use, the District proposes to reduce by 10% the annual use per connection, again by customer education and increasing rates for higher monthly consumption.
The Board of Directors will consider adopting this plan with a formal resolution (see appendix 6) and implement it through direction to the General Manager to initiate the necessary modifications to the effluent delivery facilities. Also, the District Manager will provide educational materials to customers urging water conservation in lawn watering.
An annual report describing the implementation, status and effectiveness of the water conservation plan will be submitted to the Texas Water Development Board. The General Manager and District Engineer will review the plan annually, and make recommendations to the District’s Board of Directors for any necessary amendments or modifications. |
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