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…