Location of Event of 24 Seeds 2070: 
142.376452851 2.64406510252
LAT   2 38' 39" N
LON 142 22' 35" E
Elevation 1933m (in sky above ocean)
Flux: 2.7189e18 SS

Location of bluestar's lake tower:
145.196643691 6.21550399545
LAT   6 12' 56" N
LON 145 11' 48" E
Elevation 380.0m + 40.30m
latd 386480.6065256137
lond 305204.8685743725
d 492460.42584344395
flux = 11211160.296102814

Location of crooked tower:
147.72735286 5.11719995569
LAT   5 07' 02" N
LON 147 43' 38" E
Elevation 312.6m + 23.40m
latd 267651.8985658249
lond 578920.814566301
d 637798.4386497039
flux = 6683844.404184761


Location of EPU detector experiment:
148.408681705 2.52533343609
LAT   2 31' 31" N
LON 148 24' 31" E
Elevation 30.70m +1.200m.
latd 12989.904191573161
lond 652554.6982083906
d  652683.9754159359
flux = 6382448.725411848

OLD Recorded flux at bluestar's tower: 7.280 +/- 0.003 gigastarswirls Original flux: True flux at bluestar's tower: 10.875 gSS. Distance: 500.015 km True flux at Eastern Ponyland university: 6.0705 gSS Distance 669.246 km Distance of Crooked tower. 651.95 km Flux 6.3969 gSS

Element of Honesty
    Location: The LIMINAL KEEP, under the Lake of New Canterlot.
    Power when Corrupted: False divination (tending to drive seers to despair)
    
    The element is kept with equipment to facilitate scrying in the dome of the
    Liminal Keep, Bluestar’s sanctum sanctorum. Access to the Liminal Keep
    requires exploration in New Canterlot, including possibly talking to NPCs,
    and figuring out how to access the keep (involving the hidden water level regulating 
dam. Bonus points for not draining the Lake.)

Bluestar himself found the Element in the periapocalyptic period and kept it in his
secret fortress. He knew of, and wrote about, its corruption. His journal, explaining
that the element is corrupted, can be found in the Liminal Keep, in his quarters.

After the Element of Honesty was lost by its bearer, it was found by sea ponies and brought to the archmage of the Isle of Yore, Bluestar the Brillant, for safekeeping. Bluestar recognized that the element had been corrupted, and, lacking awareness of the means to purify it, he kept it safe. First in the Lake Tower, and later, in the Lacustrine Keep. The Lacustrine keep is a keep built on top of the intake tower of the dam. Access to it is only by underwater.

Distance of 820 N mass on the lever  = 2.39x10^-2 times depth of lake

The Lacustrine keep regulates the water level of the lake. The magical cloister was permeable to air and water vapor, although not to liquid water, and consequently the lake would have evaporated or leaked out of the cloister field eventually. (When the cloister was active, the lake was dry exterior to the cloister, although moist in immediate proximity to it due to slow leakage of unusually fast-moving water molecules.) It contains a magical portal, remotely controlled by a pressure sensor in the powerhouse. The portal is connected to the abyss, and admits water but not salt, and is powered by the dimensional prison created by the Dread Pantheon, which Bluestar discovered. (He powered the cloister in the same way.)

The dam was outside the cloister. The magic portal stuff is in the old powerhouse, injecting the water into the system (reverse of the direction it used to travel. Opening the valves at the bottom of the turbine will drain the lake into the lake parish.