In the days after Austin City Council members learned they had unknowingly waived at least $50 million in city fees as part of an affordable housing deal negotiated by the offices of Mayor Steve Adler and Council Member Delia Garza, they had a lot of questions.

Those questions were answered in a Monday memo from City Manager Marc Ott. Before we get to some of the highlights of that 15-page memo, here’s a bit of background on what has happened.

The City Council gave its near-unanimous approval in December to an agreement for the Easton Park development in Southeast Austin, also known as Pilot Knob, that did the following:

Brookfield Residential agreed that 10 percent of the single-family homes would be affordable permanently, meaning the developer qualified for fee waivers for the entire development under the city’s SMART Housing program. The developer pledged to put an amount of money equal to those fee waivers into a fund, which could then be used to purchase lots and units, guaranteeing they would stay affordable to low-income households in perpetuity.

Many council members didn’t find out the amount of the fee waivers until January, when civic activist Brian Rodgers started asking questions, which in turn prompted several news articles.

From Ott’s memo on Monday:

The Austin Water Utility had initially estimated the waiver of water and wastewater impact fees could mean a total loss of $50 million to $80 million over two to three decades. The memo puts the number at $81.5 million “based upon the information provided to the City in 2010.” But there’s a whole slate of fees waived under SMART Housing. The memo estimated the waived Development Services Department fees over those decades to be between $18 million and $24.8 million. That means all told, Austin could lose $106.3 million in waived fees.Austin Water customers would pay higher rates to make up for the lost utility fees. If Easton Park were built out over 30 years, the impact on the average Austin Water residential customer would be 92 cents a month. With a 20 year build out, it’s $1.39 a month. If the city hit its cap of 1,500 fee waivers annually, it would be a $4.24 increase a month. The average monthly bill is $78.72.The mayor is right: The city is getting about $30 million in water and wastewater infrastructure that it might otherwise have paid for. But “it’s important to distinguish the timing of the negotiations,” the memo said, pointing out that a $26.5 million avoided cost for the water utility was hammered out in 2012, long before the fee waivers for the affordable housing were worked out in late 2015.The city’s Neighborhood Housing and Community Development Department knew the specifics of the deal. When it came to the details, the Austin Water Utility, the Development Services Department, the Planning and Zoning Department and the Law Department were left in the dark.There was no fiscal note on the Easton Park deal, which came in the form of a zoning ordinance, because such zoning items typically don’t require such a note or have a fiscal impact on the city. A back-up document indicating that fee waivers could total $51 million came from Garza’s office and was posted during the second reading of the ordinance in November, but city staff were unaware of it and did not include the information when the council took up the item for the final time Dec. 17. City code puts the responsibility for fiscal notes on the city manager’s shoulders.Process changes may be in the future. Four city executives wrote to Ott suggesting a coordinated staff team that would make sure “all team members are adequately involved” in projects and ensure there is a fiscal note attached to projects when the arrive on a council agenda. This team would propose further process changes.

The council is expected to discuss Easton Park at its Tuesday work session, which begins at 9 a.m. At least one council member has asked for the opportunity to reconsider the portion of the Easton Park deal waiving fees.