Lake Level Assessment for the Great Salt Lake Marina
May 29, 2008
GSL Slip Renters and Marina Users.
This has been a very confused year for the Great Salt Lake. Run-off that we usually expect in April just has not developed. The water just isn't reaching the Great Salt Lake. I have been pouring over charts this week and they make little sence for a normal runoff. I finally called Brian McInerney, NOAA's water watch expert for Utah. He is just as confused. We developed some conclusions based on the charts and what follows is our assesment and opinion of the water flow for the next few months.
In A Normal Year
In a normal year Great Salt Lake will begin to rise very slowly mid January. By late March or Early April this rise becomes very substantial with increased runoff. This rise can be as much as 1/10 a foot every three days. Runoff begins to slow late April to mid May. At this point runoff slows and evaporation kicks in as the lake warms up. Basically runoff and evaporation keep the lake level in check until the first to mid June where evaporation begins to be the dominant factor for lake level. By late June evaporation is gaining ground and the lake begins to drop rapidly from July through August. Then evaporation begins to slow in September and comes to a crawl in October. The lake usually bottoms out by Thanksgiving.
In a normal year Great Salt Lake gets 50% of its water from direct precipitation and 50% from river flows.
In a normal year we will come up 2 feet and drop 2 feet. This is not a normal year.
What Has Happened So Far This Year
Well, Great Salt Lake does create the Greatest Snow On Earth. December through February produced good moisture that came from outside Utah (Pacific Storms). But March and April were actually very dry. Although the mountains were getting plenty of snow, this snow was from Great Salt Lake. Dry Cold Fronts traveling from the Pacific would hit the moderatly warm waters of Great Salt Lake and produce plentiful "Lake Effect" storms in the mountains. IE, we have just been recycling GSL water back to the hills.
These "Lake Effect" storms have created an impressive snowpack in the Wasatch and Uintah mountains. Today that GSL Drainage snowpack is at 125% of normal (the highest percentage for the water year). Yet, for Great Salt Lake, this is a false snowpack since most of this came from the Great Salt Lake.
The Great Salt Lake begin to rise rapidly mid January. Everything looked on track for a great runoff until mid March when everything turned cold again and these Dry Cold Fronts started crossing Great Salt Lake. These cold temperatures shut off the rivers draining into the lake. The Dry Cold Fronts took moisture out of the lake and deposited it back into the mountains. This pattern, except for a short heat wave two weeks ago, has been the dominant pattern. The lake has actually dropped 2/10ths of a foot since early March. Right now the lake is staying quite stable at 4195.9 through March, April, and May. This is something that has not happened for a long time.
As stated earlier, Great Salt Lake gets 50% of its water from direct precipitation and 50% from river flows. We have actually been lower than normal on direct precipitation.
Industries Effect on the Lake
I'm not the type that makes industry the boogeyman of the environment. But I do want to spell out another factor having an impact on the lake right now. Both GSL Minerals and Mag Corp (AMAX) have evaporation ponds that border the lake. Both companies are pumping vast amounts of water from the lake and into these evaporation ponds at the current time. So this does not help the recreation uses of the lake when the water is already low.
What We Are Observing
There are three currents on the Great Salt Lake. These currents are generated by the three rivers that flow into the lake along with the Goggins Drainage. These currents are named for these rivers. The most dominant current flowing into the lake is the Bear River current. This current is fed from water flow out of Bear River Bay and the Weber/Oden rivers. This current flows west between Freemont Island and Promontory Point and then along the causeway where part of it flows into the north arm of the lake and the other part flows around Carrington Bay.
The other dominant current of the Great Salt Lake is the Jordan River Current. This current flows northwest from Farmington Bay near the Antelope Island Marina. This current then flows along the southwest shore of Freemont Island before curving down along Hat Island, Carrington Island, and down Stansbury Island before turning east and then northeast along Eardley Spit.
The third, less dominant current is the one that most sailors on Great Salt Lake observe. This is the Goggins Current and it runs southwest outside the marina and on the south end of the GSLYC race course.
The Bear River current provides 80% of the river flow to the Great Salt Lake (60% from Bear River and 20% from Weber/Ogden) and should be very strong right now. It is not flowing at all or is very light when presant.
The Jordan River current provides 20% of the river flow to the Great Salt Lake and should be flowing very strong right now. It is now flowing moderatly.
The Goggins Current provides very little water to the Great Salt Lake yet it is flowing very strong right now.
The Bear River Drainage
At the upper river guages the river is flowing at about max. But at the guages near the inlet to the Great Salt Lake, there is very little flow into Bear River Bay. This means that although snowpack is great and the water is coming down rapidly, it is not reaching the lake. It is either going into reservoirs or going into the ground. Bear River, our most important river water source, will likely be a non-player this year. This is very bad news.
The Weber/Ogden Rivers
At the upper river guages the river is flowing at about max. But at the guages near the inlet to Great Salt Lake, there is below normal flow. It is flowing at a better rate than the Bear but only contributes 20% of our river water. The fact that this source is also part of the Bear River Current and the Bear River Current is not running or running weak means that this river water source will be a very weak player this year. Not good news. The good news though is that Pineview is full and Willard will not be filled this year. We could see an increase in the water from this source for the next few months.
The Jordan River Drainage
This water is actually making it to the lake yet at below normal rates. The Provo River drainage snowpack is very high. We may yet see some significant water come from this river source. Yet, only 20% of our river water comes from this source.
The Prediction and Outlook (don't hold us to this. We're just idiots making foolish guesses)
The Great Salt Lake has likely hit its peak level for the year. We may see another small bump in the lake level but it probably will not be significant. Weather and River charts suggest that we will see warmer temperatures causing the snowpack to begin coming down again. This happened a few weeks ago. We lost a great deal of snowpack during that short spell, yet the water level did not come up. This next round of runoff may have more of an impact on the lake causing this small bump. but it will not be significant. This prediction is based on the next three weeks of charts.
A hindering factor at this point is that the lake has warmed up. It will likely exceed 70 degrees this weekend. Evaporation will accelerate. Runoff should keep this in check for awhile.
So, if the temperatures do not soar above normal, we are likely going to see our continuing trend of around 4195.9 for the next three weeks.
Long term NOAA charts are showing above average temperatures for June through August along with below normal precipitation for the sampe period. They show no drought conditions except for the Bear River area where they show a persistant or worsening drought.
Long Term Scenarios
I have basically worked out two scenarios. Neither one is good. One is devastating.
Scenario Number One
We have a moderate summer with no long stretches of above normal temperatures (we don't park in the mid 90's or have a stretch abouve 100 degree temperatures. We have average normal temperatues).
The lake should remain relatively steady through most of June and then decrease late June through October. We would loose about 1.6 feet from where we are now ending up with a lake level of 4194.3 (about where we were in 2004 for a low) This will match the worst lake level we have had since the drought developed.
This scenario is not likely based on the long Term NOAA Charts.
Scenario Number Two
We have a summer similar to last year where it was very hot and very dry. Sailing will be excellent on the GSL until late July or mid August where some of the boats will no longer be able to access the lake.
The lake should remain relatively steady through most of June and then rapidly decrease late June through October. We would loose about 2 to 2.5 feet from where we are now ending with a lake level of 4193.9 to 4193.4 (the worst level since the 1960's).
Will We Loose Access To The Lake This Year?
Yes it is possible. It is likely the deeper draft boats will be trapped by late summer to early fall. It is possible that most of the boats could be stuck in the marina by early to mid fall. The problem does not lie where we dredged. The problem lies at the end of 'B' dock. This is an area we tried to dredge but could not reach.
It gets worse.
We could loose the launch ramp to all but the shallowest draft boats.
We will likely loose the north half of 'B' dock.
We will likely loose the south half of 'E' dock
Antelope Island Marina will cease to be a viable sailing destination for all sailboats.
Final Thoughs
I want to thank Brian Mcinerny's help on this. He and I are both confused at the lack of water that is coming from the river sources. And here is where some hope lies. We do not know what is going on. We cannot account for the fact that the runoff is strong and rivers are flowing at capacity at the upper elevations yet is not making it down to the lake. We are making assumptions that the water is being held at the upper elevations or is being absorbed into the ground (we have had reports that wells, which are usually full by now, are having water problems). If our assumptions are incorrect, then there is still a lot of runoff that may make it down to the lake in June. The key is to keep moderate June temperatures and to have the water reach us rather than the aquafirs.
Dave Shearer
Harbormaster
Great Salt Lake Marina
Have you checked your docklines lately?
