He pleaded guilty to all charges, which defence counsel said was a mitigating factor.
Counsel Kimberley Jordan said her client had been co-operative with council officials and did not intend on the damage created. She appealed for a sentence of 100 hours of community service. The maximum penalty for each individual charge is $300,000 or two years' imprisonment.
Prosecution counsel Adam Hopkinson said there had been a measurable decrease in water and habitat quality downstream of the earthworks site compared from a 2015 assessment and one taken last year.
"This isn't a case where the council has just jumped in and prosecuted at the first sign of non-compliance. The council has worked for more than a year to work with Mr Singh but unfortunately, that was in vain. That's why we are here today.
"The regional council hasn't seen this kind of suspended solid levels in other prosecutions before.
"This kind of offence is the most serious offending this regional council has dealt with."
Hopkinson said it was not until an enforcement notice was eventually ordered that the offending stopped.
The court heard assessments of the water quality after the discharges measured a suspended solid levels rate of 140,000 grams per cubic metres.
Hopkinson said the only other case that came close, and was treated "seriously", involved suspended solid levels of 28,000 grams per cubic metres.
"Clearly when you have 140,000 you are in a totally different category as to [seriousness]."
Judge David Kirkpatrick said the seriousness of the offending warranted either a significant fine or imprisonment. However he was not convinced Singh, and the "wealthy" family trust his father ran, could not afford to pay.
Judge Kirkpatrick ordered a pre-sentence report, including the trust's financial details, to be made before the case was heard again on May 13. The case was adjourned.
The Kopurereua Stream catchment is listed as a habitat and migratory pathway of indigenous fish species.