Wrong kind of rain: Local precipitation patterns are changing

(Lauren Thomas | New Paltz Times)

(Lauren Thomas | New Paltz Times)

It’s never easy to tell if rainfall in a given year is normal or not without records. While the effects of this year’s precipitation can seem drought-like, the records kept at the Mohonk Preserve’s Daniel Smiley Research Center – which extend back over 100 years – don’t indicate a drop in the total amount of water. “We had a lot of questions about below-average precipitation levels this winter,” said Elizabeth Long, the preserve’s director of conservation science, “but in fact our winter precipitation was slightly higher than the 120-year average.”

As she explained, however, how the water falls does make a difference. The discrepancy in measured precipitation and perceived precipitation was largely due to the fact that during most of last winter (December 2015 through February 2016) precipitation fell as rain rather than as snow, she said. Snowpack melts slowly and seeps into the ground better than water from short quick bursts of rain does. Even though precipitation levels were above average last winter, soil moisture levels were probably lower than average for the winter months. Preserve scientists don’t measure soil moisture levels, she said.

Long didn’t ignore the facts on the ground that make some people feel like it’s a drought. Spring was drier than normal, after all, and exactly what makes for drought conditions depends on one’s point of view. “Drought can be defined by a shortfall of precipitation, which is what we can measure at our weather station,” she said. “However, it can also be measured in terms of effects on agriculture, or in water-supply levels. In terms of what we can measure meteorologically, we are not truly in a drought, although our spring season was certainly headed that way.”

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Precipitation patterns in the Hudson Valley appear to be changing. Experts say that the rain and snow which has fallen this year isn’t an unusually low amount, but it has been creating unusual impacts. The water from the short, powerful storms that seem to be more common of late is less likely to be absorbed into the ground, and that change trickles down through the ecosystem.

 

Lloyd: Reservoirs or river?

Adam Litman manages the water and sewer systems in the Town of Lloyd. Part of his job is deciding when to use water solely from the town’s reservoirs, when to pump water from the Hudson, and when to use a mix of the two sources. It’s generally more expensive to pump the river water into the water plant and treat it than to use the reservoir water. Litman is well aware of when that switch from reservoirs to river usually takes place.

“The average switch to river is mid-June,” he said. This year it was a week earlier than that. Two years ago, however, the town was still using only the reservoirs at this time of year.

Rain measurements are taken at the town’s sewage treatment plant. The 6.1 inches which fell there in July was almost double the norm. However, those were not “good rainfalls,” he said. The reservoirs are best recharged by slow, steady rain that doesn’t result in a lot of runoff. That’s not been the recent pattern. “We’re getting more frequent downpours than steady rains,” he said. In recent years, even snows are more likely to come in blizzards than as a gentle fall over several days.

Once the system is switched to river water, a lack of rain in the short run isn’t a bad thing in Highland. Runoff causes turbidity – the stirring up of sediment – that makes treatment more costly. That’s what this year has looked like so far, Litman said.

“We don’t have to backwash the equipment every hour” to clean out the clogs, he said, “Maybe every two. A day’s production of 500,000 gallons can take twelve hours, but we’ve been getting that in eight or nine.”

Saturated ground can cause problems with the treatment of sewage. Water in the ground finds its way into joints of sewer pipes and through manhole covers, increasing the volume of material that must be run through the plant. That’s called infiltration and inflow, or I&I for short, a problem that can overload the plant and lead to backups or spills.

By that measure, the rains aren’t soaking in as much this year. Wastewater volume is down.

 

New Paltz: Reservoirs or aqueduct?

The New Paltz municipal water system is also a hybrid one, drawing water from the village reservoirs and the New York City-owned Catskill aqueduct in turn. According to New Paltz mayor Tim Rogers, 55 percent to 60 percent of the water used by village residents – and others in the town whose homes are hooked up to the village system – is purchased from the New York City system.

Monthly figures vary through the year, with as much as 95 percent coming from the aqueduct in February, and as little as ten percent in July. This past January, however, 68 percent of the water came from the reservoirs, which weren’t as frozen as they normally are during that month. By contrast, only 39 percent of the water used in March was drawn from the reservoirs, Rogers said.

With planned shutdowns of the aqueduct for maintenance looming, New Paltz town and village officials are seeking local water sources for their backup supply. While those efforts have been occasionally stymied, there is still hope that at least some of that water might be used to reduce dependence on New York City, the most expensive option. Town residents on Plains Road are fighting in court over one plan, which would result in their being hooked into a water district because they’re fearful that tapping the aquifer there would disrupt their wells.

 

The Black Creek wetlands

It has been a tough year at the newly-established Black Creek water trail, maintained by the Lloyd Environmental Conservation Council. The entire trail is usable, chairperson Jack Maguire said, but the southern portion in particular is definitely on the dry side. He took a canoe that way recently, and had to portage his craft over a couple of dry spots.

“It’s been noticeably low water this year,” he said. The trail is still entirely navigable in both directions.

The first half of the southern portion is where most wildlife is visible, he said, before the water trail narrows around New Paltz Road. The two locations where he had to pick up his canoe were not long, he said, and he conceded that in a lighter kayak the portage might not have been necessary at all.

ECC members are going to have to rethink plantings for the water trail’s boat launch, Maguire said. “We lost a lot of plantings,” he added. Something more drought-resistant is going to be needed over the long haul. “Based on the last ten years, we didn’t think we’d have to worry,” he said. Since ECC members are committed to native plantings, that might mean resorting to “rocks and ferns” in the next round.

Low water levels, for Maguire and his colleagues on the Lloyd ECC, serve as a reminder that the town lacks a local wetlands protection law, something for which they have advocated for some time. Federal and state laws do exist, but “they are not enforced,” he said. A local law in the form ECC members have recommended would provide authority to monitor the condition of wetlands, and intervene if necessary to protect them.

“In this kind of situation” – with water not recharging the stream as quickly as normal – “we would be able to hire someone to evaluate any damage, and recommend possible remediation,” he said. Water is a key component in maintaining ecosystems, but Maguire said that the town’s wetlands are also vital for people who depend on wells for their water, as they replenish aquifers. Businesses, including establishments dependent on tourism, also depend upon them, he said.

There is no consensus that there is presently a drought or severe water deficit. But precipitation patterns have been different: more rain than snow, and more flash storms than steady falls. Whether this is a fluke or a new pattern due to climate change remains to be seen.

 

There are 2 comments

  1. Caryn Sobel

    Last year, I attended a NOAA Q&A session on Twitter. I had noticed how often the term “anomalous” was popping up in the forecast discussions (especially in reference to PWATS, or measurable precipitation), and I asked how long a phenomenon was considered anomalous before it was accepted as the “new normal.”

    The answer was that NOAA generally uses a 20-year period of recording to determine statistics for that phenomenon.

    We are seeing 2-3 standard deviations above normal for more of these storm predictions now, at least in the summer months. With flow patterns changing as described in this article and aging infrastructure, water (especially stormwater) management will be a true challenge for any municipality.

  2. Local Yocal

    I am curious about Mohonk’s methods…I live four miles from Mohonk (at the western base of the mountains)
    and much lower in elevation…my rain gauge has been empty for months with the exception of three or four
    rounds of brief showers. The ONLY truly measurable rainfall was a couple of weeks ago on that rainy Sunday.

    The factual measure of what has fallen as compared to the averages by month from the NWS are drastically low,
    with a roughly 7 inch deficit for the year so far, coming off of 2015’s deficit.

    This article seems to miss the greater ‘regional’ reality of drought. Antecdotaly, I can say from standing in my front yard, that yes, I’ve seen the one-localized random rain shower pass directly over Mohonk when they
    happen while the greater region around receives no rain at all. Regional is the concern – as that is what imacts the water table and inflows to our rivers.

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