Note 9 - Commitments and Contingencies (Details Textual) - USD ($)	1 Months Ended			3 Months Ended		6 Months Ended		12 Months Ended
	Aug. 08, 2017	Nov. 30, 2016	Jun. 30, 2015	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Apr. 01, 2015
Operating Leases, Rent Expense				$ 191,000	$ 200,000	$ 405,000	$ 404,000
Self Insurance Reserve				63,000		63,000		$ 23,000
Workers' Compensation, Maximum Coverage Policy									$ 1,500,000
Self-insured Amount per Individual Claim			$ 75,000
Other Noncurrent Assets [Member]
Worker's Compensation, Prepaid Amount				362,000		362,000
Expenses, Water Hauling Services [Member]
Workers' Compensation, Estimated Accruals				250,000		250,000
Subsequent Event [Member]
Payments on Workers' Compensation Claims	$ 612,000
Workers' Compensation, Accumulated Payments on Claims	1,400,000
Workers' Compensation, Remaining Policy Premiums	$ 163,000
Sales Agreement with HydroFLOW USA [Member]
Licencing Agreement, Royalties on Gross Revenues Payable, Percentage								3.50%
Purchase Commitment, Minimum Amount Committed Per Year								$ 655,000
Purchase Commitment, Current Period Obligation Payment Allocated to Following Fiscal Year		$ 220,000
Purchase Commitment, Minimum Amount Committed, Next Twelve Months								$ 875,000
Purchase Commitment, Amount Ordered						280,000
Payments for Royalties				0	0	0	0
Accrued Royalties				$ 0	$ 0	$ 0	$ 0