Lake County, Aurora negotiate IGA tweaks as Box Creek reservoir stays long-term

Lake County water managers and officials from the City of Aurora discussed revisions to an intergovernmental agreement (IGA) that would formalize Aurora's annual 40-acre-foot delivery to Lake County and add flexibility for where and when that water can be delivered, while the larger Box Creek Reservoir project remains a decades-away possibility.

The exchange came during a Lake County Board of County Commissioners work session, when Bryce Erlich, Lake County water resource manager, and Rick Kinitz, basin manager for Aurora's Arkansas and Colorado River basin water operations, outlined what the IGA changes would do and how the county's water-enterprise accounting and augmentation plan tie to Aurora's supplies.

Why it matters: Lake County relies on a mix of adjudicated consumptive-use credits and a 40-acre-foot annual delivery from Aurora to meet its blanket augmentation plan. Changes to the IGA could allow the county to bank more water, formalize use of existing recreational ponds for storage, and set terms for deliveries ahead of any final decision on Box Creek Reservoir, a proposed storage project with a current design on the order of 23,000 acre-feet in which Lake County would hold roughly 20% of storage if built.

County staff summarized the current portfolio and near-term items. Lake County's decree (referred to in discussion as 98CW173) establishes the county's blanket augmentation plan; staff said the decree was filed in 1998 and finally adjudicated in January 2017. Under that decree, county staff said the county has an average of roughly 73'74 acre-feet annually available for augmentation: about 40 acre-feet that Aurora delivers each year and roughly 34 acre-feet on average from county-owned historic consumptive use (Dairy Ditch No. 3), with dry years producing as little as about 20 acre-feet.

On the IGA revisions, staff and Aurora identified several practical changes under negotiation: - Add more points of diversion and delivery locations so Aurora can release the county's 40 acre-feet at locations closer to demand, reducing transit losses. - Clarify delivery timing and recording so the county can use Aurora's 40 acre-feet across more of the year rather than a narrow annual window. - Formalize a backfill arrangement for Hayden Meadows Recreational Pond (Hayden Pond): Aurora would backfill water the county releases from the pond so the pond's level does not fluctuate dramatically, maintaining recreation and fisheries while still providing storage credits the county can use for augmentation. Staff said Hayden Pond holds about 49 acre-feet of storage.

"Aurora has an obligation to release that much water to you, 40 acre-feet every year," Kinitz said during the meeting, describing the delivery commitment in the IGA draft and how Aurora treats the water before delivery. "It is our water right. Until we give it to you, then it is your water." His presentation emphasized that Aurora's system and the county's decree work together operationally: Aurora delivers the water; once delivered and put into county storage, the county accounts for and uses it under its augmentation plan.

Box Creek Reservoir and timeline. Aurora officials and county staff described Box Creek as a long-term, multi-decade project. Current design sketches cited in the meeting put total reservoir capacity near 23,000 acre-feet; 20% of that storage would equate to several thousand acre-feet available to Lake County if the project advances and the county exercises that allocation. Both sides emphasized that the Box Creek timeline is long (officials repeatedly referred to post-2050 as a plausible horizon) and that multiple federal and state permits, geological studies and land exchanges (including with the State Land Board and federal agencies) are required before a permitable project could be built.

Short- and mid-term options. Because Box Creek is far off, staff said the IGA revisions are designed to help the county now: solidify the perpetual 40-acre-foot delivery, allow greater flexibility for where that water can be delivered, and let Hayden be used as a practical short-term storage site through backfill accounting. Aurora's presentation said the city has in the past delivered that 40 acre-feet in increments throughout the year and staff wants to put that practice into the IGA so Lake County can rely on it consistently.

Water-rights context and risks. County staff walked the board through Colorado water concepts (acre-feet, cubic feet per second, priority dates, augmentation) and explained local constraints: the Arkansas River Basin has many senior (pre-1886) rights and Colorado must account for interstate obligations to Kansas; in the Arkansas Basin, most junior water rights are unreliable. Staff also warned that new applications and substitute water-supply plans (SWSPs) and recent water-court filings by mining or development interests in the lower basin could affect local groundwater and surface-water conditions. Staff identified recent local activity including SWSPs and a recent water-court application tied to a proposed well field.

Commissioners and other speakers pressed staff on operational details, local impacts and timeline. The board and other participants asked about storage losses (evaporation), how Box Creek would be filled, whether historic tailings or cultural resources would be affected if an area were flooded, and how the county's own augmentation station and Dairy Ditch No. 3 diversions could contribute to filling future storage. Staff and Aurora said the county would keep its augmentation credits and that the parties were trying to preserve local use and mitigate recreation impacts.

Community users and utilities raised concerns. Paul Carranova, general manager of the Manoa del Toro (a local domestic water association), said his system is moving from a flat-fee model toward meters and that demand is seasonal; he and the county discussed how augmentation and any new deliveries could affect small systems and private wells. Staff flagged recent reports of failed wells in some subdivisions tied to changing hydrology and noted a continuing need to monitor and to evaluate well depths, permit conditions and augmentation replacements.

Next steps. County staff said lawyers are reviewing the latest draft language and that the IGA revisions are close to final staff negotiation; the county's outside water attorney (Chris Geiger of Belkton & Green, cited in the meeting) was expected to review final wording. No formal county action or vote was taken during the work session. County staff recommended a future board work session to review the county's water-marketing policy, which sets limits on how county augmentation water may be leased or sold.

"We're near the finish line," Bryce Erlich, Lake County water resource manager, told the board about the county's internal accounting and reporting for the water enterprise. He and Aurora staff asked the board for direction on the backfill/Hyden storage approach and signaled they would return with the final legal review and a recommendation when the IGA drafting is complete.

What remains unsettled: whether some land swaps and permit outcomes (including State Land Board negotiations and federal site-level geotechnical work) will proceed, exact legal language on delivery and storage accounting, and the full list of contingencies for long-term Box Creek development. County staff repeatedly cautioned that Box Creek remains Aurora's longer-term timeline and that the IGA is intended to give Lake County near-term operational certainty without ceding long-term oversight over county augmentation rights.