check_stratification: Calculate frequency of mixed (unstratified) conditions
In WDNR-Water-Use/CSLSscenarios: CSLS MODFLOW Scenario Analysis

Given a data frame with columns for "lake" and "level" as well as additional information about the elevation at which lakes stratify, evaluate the frequency of mixed conditions at all lakes with stratification information.

check_stratification(
  this_rule,
  this_hydro,
  metric_uncertainty,
  strat_info = data.frame(lake = "Pleasant", elev_m = 297.67)
)

`this_rule`	data frame with information on "percent", "difference", "significant_if" (i.e., "higher" or "lower") for a single indicator.
`this_hydro`	data frame with the hydrologic metrics (solute_budget) to evaluate.
`metric_uncertainty`	data frame with lake, metric, variable, and allowable "difference" due to uncertainty in the metric. Currently evaluated as the standard deviation in the "no irrigation" scenarios of the metric.
`strat_info`	a data frame with the "elev_m" at which each "lake" switches from stratified to mixed.