Avon plans to build 700 units of affordable housing. Where will residents get their water?
Avon's upper valley can be served very efficiently, meaning 16 acre feet of water from Eagle County's designated Eagle Park Reservoir stores for affordable housing should be enough for all 700 units
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As Avon prepares to annex the nearly 100-acre State Board of Land Commissioners property that borders the east end of town to build 700 units of affordable housing, a question arises: Where will water service come from?
The town is a member of the Upper Eagle Regional Water Authority, which provides water service to Avon and five metro districts. The six authority members have allocated water rights that they lease to the authority in return for service. The authority, which came together in 1984, has also developed more water sources over time that firm up the security of members’ water.
Most of the water the authority controls is already allocated to specific uses, with a few minor exceptions. This means that with a new parcel of land being added to Avon, new water has to be found for the development, as the area is not currently in any water entity’s service area.
“When we did our modeling, we realized that the authority really didn’t have any more water (for new commitments) beyond what (the authority has) already committed to (serve),” said Jason Cowles, director of engineering and water resources at the Eagle River Water & Sanitation District (district staff also works for the authority).
The modeling showed that in an extreme dry year, existing users would need nearly all of the authority’s in-basin storage supplies, Cowles said. “So, if we were committing to new uses, we were at risk of having shortages in dry years,” he said.
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Collaborating with Eagle County, authority staff have created a plan to make water available for the State Land Board development.
How location affects water
Within the authority’s service area, where something is developed impacts how much water it needs.
Accounting for water “isn’t like money,” said Diane Johnson, communications and public affairs manager for the Eagle River Water & Sanitation District.
Water “goes a lot further” in the State Land Board location upvalley than it would, for example, in Edwards, Cowles said.
The location where water is taken out of the river, or the point of diversion, and the location where that water is returned to the river, or the point of return, matter because the space between the two affects how long water is removed from the river. The space between the point of diversion and the point of return is referred to as the gap in the river.
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The biggest gap in the river in the authority and district’s service areas is in Edwards. There is effectively no gap in the river in Avon, because the authority built a pump station that sits very close to the point of return, and serves as an alternate point of diversion when streamflows are low, meaning that as water is removed from the river in Avon, the same amount of water is immediately returned.
The gap in the river matters most during months when streamflows are low. Because Edwards area has a gap, in certain months, all of the water diverted out of the river in Edwards has to be replaced, or augmented, with in-basin sources. With no gap, projects upstream of the Avon drinking water and wastewater treatment facilities do not require as much augmentation.
The district and authority can directly augment stream flows with upstream in-basin storage buckets — the Black Lakes, Eagle Park Reservoir, and some from Homestake Reservoir — whose purpose is exclusively to serve for augmentation.
Housing in Edwards versus Avon will use up more of the limited water available per unit because the gap in the river requires more augmentation water.
“We can serve six to eight units at the state land board (property) with the same amount of water for one unit in Edwards,” Cowles said.
For a concrete example, the 6 West Apartments development in Edwards used 12 acre-feet of water for 120 housing units, while the 700 housing units in Avon will be covered by 16 acre-feet of water.
“Some of that is the ratio of indoor to outdoor, but a lot of that is the location and how much water has to be paid back to the stream,” Johnson said.
There is a difference between indoor and outdoor uses of water. For indoor water, such as showering or washing dishes, which goes down a drain, 95% is returned to the river. For outdoor water use, such as irrigation, the state says 25% on average gets returned to the river, though the actual number may be less.
Avon adopted minimal outdoor irrigation design codes for landscaping, requiring that new developments are designed with water efficient landscapes.
The State Land Board development will “use water efficiently because of those codes,” Cowles said.
How much water is there to serve this new development?
Eagle County purchased 100 acre-feet of water in the Eagle Park Reservoir. In 2020, the county conveyed the water to the authority to be used for affordable housing projects.
The only project the county has dedicated its Eagle Park Reservoir water to so far is the 6 West Apartments development in Edwards, which received just over 12 acre-feet in 2018.
“If (the authority) didn’t have that county water, there may not have been any water to be able to play with to be able to entertain the state land board proposal,” Johnson said.
The 16-acre feet will cover the 60,000 square feet of commercial development that the authority does not currently serve, the 15 trailers belonging to Colorado Department of Transportation workers that the authority does currently serve, the net increase in 685 units to cover 700 units total, and enough water for one acre of irrigated turf for parks and ballfields.
The 16-acre feet designation includes more water than the service area should currently need as protection against climate change-induced changes, including a predicted longer growing season, and hotter, drier weather in the future.
The water is not fully guaranteed yet. “This is the first step,” Cowles said.
During its Feb. 22 meeting, the authority board approved the request for the amount of water, which will now go to Eagle County for approval. If the county confirms the State Land Board can use the water, the next step will be to draft and execute a water service agreement with the State Land Board, and then for the authority to issue an ability-to-serve letter. All of this should be done within about two months, before the end of Avon’s annexation process.
