McPhee Reservoir fell 11,000 acre-feet of water short of filling to capacity this year, reported manager John Porter at the regular meeting of the Dolores Water Conservancy Board this month.

The lower-than-optimum level won’t mean less irrigation water for farmers, though. The purpose of a reservoir is to store water to compensate for drought years, so there is always water to draw in the system. Total water demand is only half of the available capacity in the reservoir during any one year, Porter said.

A combination of lower-than-normal snowpack, high evaporation caused by weeks of warm and windy spring weather, no measurable rainfall and a larger-than-necessary spill for the rafting season contributed to the shortage.

Predicting runoff is a mix of intuition, luck and data-gathering from various low and high elevation snowpack measuring devices. When that technology reaches its limit, Porter turns to the camera’s eye, comparing current and historical photographs of high-altitude snow fields in the La Plata Mountains as a base for predicting how much more water will ultimately make its way to McPhee.

It’s not really an exact science.

"When I came into John (Porter’s) office (in mid April) he had pictures spread out all over and I said ‘Has it come down to this?’," said Don Schwindt, president of the DWCD board.

It does — leading, in the end, to "gut feeling" speculation on the whims of Mother Nature regarding snowmelt rate and volume. The DWCD has a good record (10 out of 12 seasons) of managing the reservoir to fill when the snowmelt and spring rains made it possible. Twice, In 1990 and 1996, the region suffered a drought and there was not enough runoff to fill, and only once before did it fail to fill to capacity when it could have.

Porter, manager of DWCD since 1985, is batting a respectable .833 average on his predictions. He said the scanty spring rains this year caught him off guard.

"We had been expecting some storms, but they never came," Porter said, explaining that it is not good reservoir management to let the man-made lake fill to capacity and then spill the extra, leading dam operators to become defacto weather forecasters.