The city of Santa Fe began releasing water Friday from Nichols Reservoir to prevent expected weekend rains from flooding over the dam.

The city doesn't have a written flood-control plan. It relies on staff experience to decide how much space is needed in the two municipal reservoirs to handle a big water runoff event. "We try to leave a buffer space, about 5 percent, in the lower (Nichols) reservoir," said Gary Martinez.

On Friday, Nichols Reservoir, which has a 223 million-gallon capacity, contained 208 million gallons.

"I want to lower it just a hair in case there's a lot of rain over the weekend," Martinez said.

The city will release about 12 million gallons of water through the weekend, he said. The release could continue into next week, depending on precipitation, storm-water runoff and reservoir levels.

Two weeks ago, the rain came so fast it filled up McClure and Nichols and spilled over the Nichols dam. "It was a lot of rain in two or three days. We've seen this before. We expect this," Martinez said.

The rain rushed down side canyons and tributaries below the Nichols dam, which added to the flow roaring down the Santa Fe River channel.

The city will have an emergency plan in place by the end of the year to address any potential breach of the dam. The plan is a new requirement by the State Engineer for "high hazard potential dams" like the city's Nichols and McClure reservoir dams.

A high hazard potential dam is one where a breach or a miscalculated release of water has a high probability of causing loss of human life and economic damage, according to the 2004 definitions set by the Federal Emergency Management Agency.

The city's Public Utilities Committee approved a $92,685 contract with the Los Alamos based engineering firm URS Corp. to help create the emergency action plan and an operation manual for the McClure and Nichols dams.

The plan will address issues such as how to alert residents below the dam in the event of a breach and how the emergency service agencies will collaborate in the case of such as disaster.

In other water news, city water staff hope to submit a proposed 40-year water supply plan to the committee Aug. 6. That plan looks at how the city can manage its water resources — from the reservoirs, city wells and eventually a river diversion project on the Rio Grande — to meet long-term water needs. Advocates for a regular water flow in the often dry Santa Fe River are hoping the plan will include some provision for releasing water more often from the city's reservoirs.

Santa Fe is facing a potential shortfall of 2,700 acre-feet of water by 2020 in a drought year unless other water resources can be identified, according to Claudia Borchert, a long-range water planner for the city. That gap between supply and demand was reduced by more than 2,000 acre-feet in the last few years in part because of the conservation efforts of city water customers, Borchert said.

An acre-foot of water equals about 325,851 gallons.

Contact Staci Matlock at 470-9843 or smatlock@sfnewmexican.com.